CA2375675A1 - Endodontic systems and instruments for the anatomical, sectional and progressive corono-apical preparation of root canals - Google Patents

Abstract

A root canal is sequentially cleaned in sections from the crown to the apex by dividing it into three sections including an operative coronal portion, an operative middle portion and an apical portion. After an opening is formed into the tooth to provide access into the root canal, the opening is preferably rectified to remove obstructions so that the anatomical root canal can be fully accessed. The pulp material is then sequentially removed from the portion of the root canal above the apical portion of the root canal with a set of instruments (410). The apical portion is then cleaned with another set of instruments (470). An optional set of instruments (440) can also be used to improve the access into the apical portion such that irrigants can be delivered to the apical portion. Cleaning of the pulp material from the root canal also shapes the root canal to ease filling of the root canal with a filling material. The root canal preparation and shaping are completed while maintaining the original anatomy of the root canal. Each file has an abrading portion and terminates at a tip. The files of the set (410) of instruments used to clean the portion of the root canal above the apical portion have properties which enable the abrading portion of the file to conform to the configuration of the root canal while simultaneously moving the file in a cleaning motion.

Description

WO 00/74589 PCT/iJS00/08122 ENDODONTIC SYSTEMS AND INSTRUMENTS
FOR THE ANATOMICAL, SECTIONAL AND PROGRESSIVE
CORONO-APICAL PREPARATION OF ROOT CANALS
BACKGROUND OF THE INVENTION
1. The Field of the Invention The present invention is related to the field of endodontistry. More particularly, the invention is related to systems and operating methods for the preparation of root canals for obturation. The systems and methods involve the use of at least instruments which are dedicated for specific purposes in the inventive methods and systems and are designed for minimal intrusion into the apical portion.

2. The Relevant Technolo~v To preserve a tooth with a pulp that is diseased or is potentially diseased, it is generally necessary to remove as much of the pulp material as is possible from the pulp canal of the tooth, to shape the root canals) without excessively weakening the root canal walls, to prevent or minimize the presence of bacteria through the use of irrigants and dressings, and lastly, to clean the walls of the root canals) by removing the smear layer created during instrumentation of the root canal(s). These steps are all done to prepare the root cavity for sealing or obturation which involves filling the root canal with biocompatible materials, such as gutta percha, before the pulp cavity is sealed, thereby promoting the healing and functional recovery of the tooth. This procedure is referred to as root canal therapy.
As indicated hereinabove, root canal preparation involves pulp removal, cleaning of the root canal walls and shaping of the canal walls. This is typically achieved through a guided procedure with the use of instruments which are moved either manually, mechanically or by combinations thereof. These instruments are files or bits that are configured to bore and/or cut. Mechanical instrumentation can be achieved through the use of endodontic handpieces coupled to instruments such as files. The endodontic handpieces can impart rotational motion to a file, reciprocal motion by alternately rotating a file clockwise and counterclockwise, sonic movements or ultrasonic movements.
Before endodontic therapy is begun, a preoperative x-ray image is obtained to assess the health and the pathological status of the tooth and to determine the approximate initial length of the root canal(s). Once the approximate length of the root canals) has been determined, an instrument can be selected for use in the root canal which has an appropriate working length.
The schematic representations shown in Figures 1 A and 1 B are similar to a typical x-ray image. As shown in Figures 1 A and 1 B, an x-ray image of teeth generally show teeth 10 with sufficient clarity to view some of the properties of roots 12 and the root canals 14 located therein, particularly the location of the radiographic apex 17. The location of the radiographic apex often does not coincide with the true apical terminus of the canal just beyond the apical foramen 16. The distance between radiographic apex 17 and a fixed reference position on the occlusal surface of a tooth is used to determine the working length of the instruments. Figure 1 B, which is an enlarged view of root 12a shown in Figure 1A, shows the relative position of the radiographic apex designated at line 17 in relation to that of the endodontic apex and the anatomical apex designated respectively by lines 18 and 19. This condition is typical of an apex in living teeth, whereas a pathological apex can appear in a partially autolyzed state, as shown in Figure 34C.
Preoperative or intraoperative x-ray images of a tooth requiring endodontic treatment, such as the x-ray image depicted in Figure 1 A, are obtained by lingual placement of film packets as shown in Figure 2 at 22 which is supported by an x-ray film packet holder (not shown) and a long cone x-ray head (not shown) located outside of the cheek. Although, x-ray images obtained as shown in Figure 2 from a buccal-lingual x-ray projection are generally useful for determining the overall characteristics of a tooth, the approximate initial length of the root canal(s), and the working length for a file, such images provide only limited information regarding the overall anatomy of the root canal.
The information is limited because only one dimension of the overall anatomy of the pulp cavity can be viewed in vivo. In the standard buccal-lingual projection such images show only a linear profile of the root canal and cannot show a tridimensional view of a tooth and its root canal(s). Although, it would be very helpful to view a tooth from a position between the teeth or from the interproximal space such a mesial-distal view cannot be clearly produced when the tooth is still positioned in a patient's mouth. Since information is needed of all three dimensions in order to correctly understand the overall anatomy of the root canal and yet only two-dimensional images of a tooth can be obtained, x-ray images are sometimes relied on to reach incorrect conclusions regarding the anatomy of the root canal. More particularly, if not properly evaluated, x-ray images

3 can be misleading as to the actual length of the root canal and the position of the foramen or foramina.
The difficulties encountered by an endodontist in assessing the overall anatomy of teeth from just the x-ray images obtained from buccal-lingual x-ray projections can be clearly identified with reference to Figures 3-6. Figures 3A-6A are longitudinal cross-sectional schematic views of extracted teeth taken from the front or back of the respective tooth which correspond with typical images obtained from buccal-lingual x-ray projections. Figures 3B-6B are longitudinal cross-sectional schematic views of the same extracted teeth shown respectively in Figures 3A-6A taken from the mesial-distal or side view that cannot be obtained or seen while the teeth are still positioned in a patient's mouth.
Note that by varying the angle of incidence of the x-ray beam mesiodistally and distomesially additional x-ray images can be made which provide some additional information about the anatomy of the tooth. However, we can never obtain a three-dimensional image!
Figures 3-4 illustrate that in order to properly prepare a root canal it is necessary for practitioners to rely heavily on their experience, knowledge acquired through a study of typical anatomical structures, and on their visually acquired experience with longitudinal and transverse dental cross-sections at various heights. Figure 3A depicts a lower premolar 30 from the buccal-lingual view of the tooth which shows root 32 and a root canal 34 therein that appears to be rather narrow and to have a relatively uniform perimeter along its length. Figure 3B, however, shows that when seen from the mesial-distal view, the root canal is initially fairly wide over more than half its length, and then tapers significantly before reaching the apical foramen 36. Comparing Figure 3A with Figure 3B clearly shows that when limited to knowledge derived from an x-ray corresponding to the image shown in Figure 3A, the practitioner may not be able to accurately assess the anatomical structure of the root anatomy. Additionally, Figure 3C
shows that instead of an apical foramen there may be double, triple or quadruple foramina as indicated in research performed by the applicant and by others. The triple foramina 36a, 36b and 36c shown in Figure 3C may not be detectable when viewed only from the buccal-lingual view shown in Figure 3A.
Figure 4B depicts an upper premolar 40 with roots 42a and 42b and root canals 44a and 44b located therein. Comparing Figure 4A and Figure 4B reveals a problem

4 which is similar to the problem revealed by comparing Figure 3A with Figure 3B. More particularly, by comparing Figure 3A with Figure 3B or Figure 4A with Figure 4B, it is easily understood that the practitioner may not be able to accurately assess the anatomical structure of the root anatomy when limited to knowledge derived from an x-ray image.
Since the configuration of pulp chamber 48 may be difficult to accurately and fully ascertain from only an x-ray image, a practitioners also relies, as indicated hereinabove, on accumulated experience, knowledge of dental anatomy, and knowledge of typical anatomical structures.
The potential inaccuracy of a conclusion derived from information obtained from an x-ray image is further illustrated by comparing Figure SA and Figure SB and also Figure 6A with Figure 6B. More particularly, as discussed hereinbelow, Figures

5-6 show that practitioners encounter anatomies with widely varying aberrations and intercommunications of root canals which may not be apparent to the practitioner from the limited information derived from x-ray images.
Figure SA depicts a mandibular or lower incisor 50 from the buccal-lingual view of the tooth which shows root 52 and root canal 54. Figure SB depicts the same lower incisor 50 from the mesial-distal view of the tooth. The mesial-distal view shown in Figure SB clearly reveals that root canal 54 branches and then rejoins to have a single foramen 56. Root canal morphological variations, such as that shown in Figure SB, may not be detectable by a practitioner who relies solely on a preoperative or intraoperative x-ray image, such as the image of lower incisor 50 shown in Figure SA.
Similarly, a root canal may branch without merging so as to yield multiple foramina, such as the root canal of a lower first molar 60 shown in Figures 6A-6B. Again, the buccal-lingual view, as shown in Figure 6A, provides inadequate information when compared with the depiction taken from the mesial-distal view of mesial root 62b in Figure 6B. Figure 6B reveals that branches 64a and 64b do not merge and accordingly have two foramina 66a and 66b.
In addition to the morphological variations in anatomy as discussed above, consideration should also be given to the substantially different perimetrical configurations of root canals, as revealed by various dental cross-sections shown in Figure 7 and Figure 8. Additionally, the shape of root canal perimeters varies not only between different types of teeth as shown in Figure 7 and Figure 8 but also along the length of a single root canal of a tooth as is illustrated in Figures 9A-9B.

Figure 7 shows a classification system devised by A. Latrou which divides the perimetrical anatomies of root canals into those that have primarily a tubular morphology and those that have primarily a laminar morphology. Examples of root canals with tubular perimetrical anatomies are shown at 70, 71, and 72 which are respectively primarily oval, 5 round and triangular. The laminar perimetrical anatomies include root canals with essentially slit-like configurations such as those shown at 73, 74, and 75 which are respectively primarily straight, semi-lunar shaped, and figure eight shaped due to the vestibular and lingual bulges. The laminar shape is more common than the tubular type root canals.
Figure 8 shows cross-sectional views of the middle third of different teeth 80a-801 that have been extracted and then cut along a transverse cross-section of the tooth to show root canals 82a-821 as well as corresponding pulp chambers 84 and floors or cervical aspects 86. Conventional file instruments 88 are also shown inserted into root canals 82.
From this view, which can only be seen in vitro, it is evident that a certain degree of variation occurs in the perimetrical anatomy of the pulp cavity of teeth. The practitioner may at first be unaware of such variation; however, the practitioner must keep in mind the possibility of such variation while working with instruments in the root canal so that all of the canal walls will be treated and the irregularities caused by greater parietal thicknesses can be removed without unduly weakening the walls.
Figures 9A depicts a maxillary right upper first molar 90 with dashed cutting lines included to identify the division of the tooth into transverse cross-sections for segmentation as shown in Figure 9B. Figure 9B displays roots, 92a, 92b and 92c of molar 90 as cut into four respective segments, 100-103, to clearly show the variations of root canals 94a, 94b and 94c. Also displayed in Figure 9B are segments 104 and 105, which respectively contain the pulp chamber 98 and its floor. A comparison of the perimeters of root canals 94a, 94b and 94c starting at segment 104 as each root canal tapers to its respective apices 96a, 96b and 96c, clearly shows that the perimeter anatomy varies and transitions in configuration along the entire length of each root canal. So not only must a practitioner deal with root canals having different shapes as discussed in reference to Figure 7 and Figure 8, but the practitioner must also utilize an instrument in a root canal with a perimetrical or circumferential anatomy that varies depending on the height at which the observation is made.

6 From the discussion above, it is apparent that when a practitioner views a preoperative or interoperative x-ray image of a tooth, the practitioner can only guess about the actual anatomy of the pulp cavity and the root canals) of the tooth.
While the practitioner may be able to confirm that a root canal has been cleaned along the length of the pulp chamber from the coronal portion to the apex of the root, the length that has been contacted or abraded by the file may only be a portion of the root canal system.
Since it is impossible to obtain a mesial-distal view of the root canal or to view the perimetrical anatomy on different points along the length of the root canal, the practitioner is prevented from obtaining a proper preliminary understanding of the overall root canal anatomy in order to assess the necessary relationship between the canal walls and the instrument inserted in the root canal. Accordingly, as shown in Figure 10A and Figure IOB, when a file instrument such as instrument 114 is inserted as far as the apex into a root canal such as canal 112a of tooth 1 10a or canal 112b of tooth 11 Ob and then rotated, significant portions are not cleaned.
The inability to clean all surfaces of a root canal by merely inserting and rotating a file instrument in a root canal is further illustrated by Figure 8. Figure 8 depicts the position of file instrument 88 in transverse cross-sectional views of root canals after file instrument 88 has been inserted to the apex of each respective root canal.
Figure 8 clearly shows that simply drilling from one position into the root canal will often miss large sections of the perimeter of the root canal, thereby leaving portions of live, diseased or necrotic pulp material undisturbed. If the operator is unable to apply the instrument to every segment of the perimeter of the canal, the undisturbed pulp material may ultimately cause undue pain, lengthy healing times or even cause the procedure to fail.
Solvents or irrigants such as sodium hypochlorite may be used to further clean the root canal.
The next step is neutralization or obturation of the root canal which involves coating or filling the root canal with a plastic obturation material such as heated gutta percha. The object of obturation is to prevent the ingress of bacteria or tissue fluids which might act as a culture medium for any bacteria remaining within the root canal system by sealing the system. In order to reach the recesses with the filling material that cannot be treated with the instruments, vertical pressure must be applied with a plugger; however, there is never any assurance that all of the necrotic residue has been coated.
There is also a risk that such techniques will cause infected material to be pressed beyond the apex.
Such an extrusion of infected material beyond the apex is very undesirable as it may

7 contain polymicrobial loads or charges that may produce damaging bacteremia or cause chronic inflammations of the apical and periapical tissues.
Based on all of the foregoing observations, it can be concluded that inadequate attention is given to understanding the dental chambers on a three-dimensional basis, the varying configurations of the perimeter of the root canal(s), the diameter of the canals, and the thickness of the walls. Note that research is still needed to investigate and catalog the thickness of dental walls in order to increase understanding amongst practitioners.
The inability to fully identify the anatomy of the pulp cavity restricts the ability of the practitioner to confidently conclude that the procedure has been successful. Although problems may result from having incomplete information regarding the anatomy of a particular root canal, many practitioners using conventional methods and instruments are not overly concerned with completely cleaning the entire root canal since their failure rate is not at an unsatisfactory level. While these conventional methods and instruments may result in satisfactory failure rates, it would be very beneficial to still lower the failure rate and to better preserve the integrity of teeth.
As discussed hereinbelow, most of the methods and instruments that have been and continue to be employed and produced are relatively arbitrary with regard to root canal anatomy. To compensate for the limited understanding of the inability to contact all root surfaces and the lack of knowledge of the actual anatomy of the root canal, many working methods have been devised, which in turn have prompted the creation of a multitude of instruments of varying diameters and sizes.
With regard to operating procedures, there are two basic methods from which all of the canal-preparation techniques can be derived. These methods have been interpreted by various authors in an operational context and also in terms of the instrumentation. The primary conventional systems and methods for removing pulp material from the root canal of a tooth are the apico-coronal (step-back) technique and the corono-apical (crown-down) technique. Although these conventional cleaning techniques both rely generally on sequential increases in the diameter of instruments inserted into the root canal, the step-back technique involves cleaning the root canal from the apex toward the crown while the crown-down technique involves cleaning the root canal from the crown down to the apex. Each has its own unique benefits and disadvantages which are discussed hereinbelow.

8 The step-back technique involves the use of various sets of file instruments which are sequentially inserted into a root canal after the root canal has been exposed by removing the roof of the pulp chamber as depicted in Figure 1 1A and Figure 11B. More particularly, before pulp material 160 can be removed in accordance with the step-back technique, an instrument, such as instrument 120 shown with bur 122 in Figure 11 A and Figure 11 B, is utilized to remove the overhanging portions of enamel 152 and dentin 154 in order to provide access into the pulp chamber 156. Figure 12 depicts a set of step-back file instruments with each file instrument 130 comprising a handle 132 connected to a file 134 or a shaft with tines or an abrading portion. Each file has a tip 136 opposite a top end 138 where file 134 joins handle 132. As viewed in Figure 12 from left to right, the diameter at top end 13 8 of each file increases progressively from the smallest to the largest such that the diameter of 138a is less than the diameter of 138b. The diameter of each successive file at tip end 136 is also successively larger. Accordingly, the taper of each file remains essentially the same even though each file is progressively larger that the preceding file.
In the step-back technique, the apical portion of the tooth is prepared first and then the remainder of the canal is flared from apex to crown. This process essentially involves inserting a series of progressively larger files into the apex of the root canal and rotating each file and/or moving the file up and down in a longitudinal motion until a file can be inserted that is considered to be a suitable standard size for completing the process or that meets some resistance to rotation. The rest of the canal is then flared by sequentially using each file in the set, as shown in Figure 12, with each file being larger than the preceding file and by alternately advancing and then withdrawing each instrument.
Figure 13A depicts a molar 150 being prepared by the step-back technique after the removal of enamel 152 and dentin 154 that extend into pulp chamber 156, and after the first stage of the step-back technique has been completed. The first stage of the step-back technique involves the insertion of a file into pulp chamber 156 and into root canal 158a in order to remove material 160 in the lower portion of the canal above the apex or apical end 162a. After the portion above apex 162a is cleaned, each file shown in Figure 12 is sequentially inserted downward toward apical end 162a of root canal 158a, starting with file instrument 130a as shown in Figure 13A. As a result of this technique, the diameter of the area being contacted at the apical portion is increasingly larger.
Figure 13B is a cross-sectional view taken along cutting line 13B--13B in

9 PCT/US00/08122 Figure 13A of tooth 1 SO during cleaning of root canal 158a with file instrument 130a in the step-back technique. Insertion of the files of the other file instruments 130b and 130c may further clean out material 160 because each file has an increasingly larger diameter.
With each increase in diameter, the rigidity increases and the flexibility of the files decreases. As a result, it becomes increasingly difficult for the files to adjust to or to follow the contours of the perimeter surfaces of the root canal. This reduced flexibility also increases the likelihood that the files will fail to contact some portions while removing too much of the surrounding dentin 154 in some areas through excessive abrasion and resulting in overthinning of the walls.
Note that the views depicted in Figures 13A and 13B depict the problem previously discussed with regard to the difficulty in assessing the actual root canal anatomy in vivo. When viewed in Figure 13A, it appears that the root canal has been cleaned; however, Figure 13B shows that a significant portion of material 160 remains.
Accordingly, when the root canal is viewed in an x-ray photograph which is the same view shown in Figure 13A, a practitioner may mistakenly believe that the tooth has been adequately cleaned. This mistaken belief may be further incorrectly relied on as the root canal is widened by the insertion of the larger files which gives an impression of complete cleaning. There is resultingly some possibility for failure of the root canal therapy due to incompleteness.
Not only is the completeness effected by the use of a set of files wherein each file is more rigid than the preceding file but the ability to safely move the file within the canal is also limited. More particularly, the increasing rigidity results in decreased ability to negotiate the curves in the canal. Significant problems that can result from inserting increasingly rigid files and also from initially inserting a file all the way down to the apex includes laceration and transportation of the apical foramen, as well as misdirection and perforation of the wall. As shown in Figure 14A, after tooth 170 was prepared by removal of portions of the enamel 172 and dentin 174, file 132 was inserted into root canal 176 and perforated apex 178. Perforating the apex can also result from an error in estimating the length of a root canal, by failure of a stop such as stop 140 to remain at a predetermined position or by failure to observe the calibration or graduation hatch markings on the file, which can be used instead of a stop to designate the length.
The apex can be perforated by extrusion of the infected material 180 through the apex due to the force exerted by the file on the material as the file is pushed downward to reach the apex. As a result, the periapical region can be invaded and contaminated.
The potential for extruding infected material through the apical foramen of a necrotic tooth during the initial insertion of a file instrument all the way down to the apex is a particular disadvantage of the step-back technique. Another disadvantage is that the 5 procedure has identical steps for working in either necrotic or vital root canals. In addition to exposing the tissue surrounding the tooth to the infected material, apical perforations may allow irrigants, amalgam filling or obturating material to flow out of the apex. Such apical perforations, as well as wall perforations, may delay tooth healing and may compromise the outcome of the therapy.

10 Perforations can also occur due to a failure to maintain a proper working length of the instrument during the procedure. As the canal is widened, curvatures are straightened thereby decreasing the required working length needed for the instrument to work. Accordingly, the rubber stop 140 must be adjusted, thereby continually providing an opportunity for the instruments to become contaminated by bacteria. To properly determine the appropriate working length, many radiographs must be taken throughout the operation as the canal is continuously being modified, which alters the length. The time required to obtain the x-ray photographs or images and to adjust the working length of the instruments by repositioning the stops can result in a lengthy process.
The step back technique is also time intensive because a large number of instruments are required to complete the root canal therapy.
As shown in Figure 14B, another problem is the formation of ledges such as ledge 182. Ledges can occur when a practitioner attempts to insert a file such as file 134 as far as the apex and the file is too inflexible to properly curve with the root canal or move around a protrusion. When a file is too inflexible to curve or flex as needed and is halted prematurely, the downward pressure exerted on the file, in conjunction with the tendency of the file to straighten itself, causes the tip of the file to dig into the side of the root canal and form a ledge. Such ledges are difficult to bypass; and if the ledge occurs very close to the apex, the ledge may give the practitioner the mistaken impression that the apex has been reached.
The crown-down technique was developed for several reasons. It was desired to shape the canal "conically" so as to keep the diameter of the foramen as straight as possible. The crown-down technique was also developed to prevent the discharge of septic material or obturation material from the apex after the initial canal-preparation step

11 and to prevent subsequent vertical condensation due to the vertical pressure used to obturate the canals with heated gutta-percha. Additionally, the crown-down technique was intended to reduce the number of instruments utilized compared with the step-back technique. However, as discussed hereinbelow, significant potential problems may inherently result from use of the crown-down technique.
The crown-down technique generally involves the use of a set of file instruments wherein each file in the set of file instruments has a progressively different diameter at the top of the cutting portion of the file, i.e., the point where the file becomes smooth and no longer has cutting capabilities. The smooth portion may have a constant diameter. The diameter at the top of the cutting portion of each file may be either constant or graduated for the entire set of instruments such that the top of the cutting portion of each file is progressively larger than that of the preceding file. As a result of this configuration, the taper of each file is larger than the preceding file in the set. By using such files of increasingly larger diameters, the area that is initially and subsequently abraded, as work proceeds toward the apex, will always be primarily at the top portion of the root canal.
Gradual progressive conicity or taper, and the constant diameter of the tip (characteristics which, paradoxically, have been inflated, despite the prior teachings of the present applicant in earlier patents, such as Italian patents No. 1,199,941 and No.
1,169,326, and U.S. Patent No. 4,971,556) are characteristics which are now so standard among the multitude of crown-down instruments made of nickel/titanium that have been introduced onto the market, that competitors have shifted toward other features of the instruments. For example, increasing value is being attached to the so-called "overall"
originality of an operating procedure that uses so-called "dedicated"
instrumentation to solve the multiple problems associated with root canal preparation in terms of ergonomics, operational safety, the time and cost of the procedure, and the likelihood of success.
One example of the operational deficiency of the crown-down method lies in its association with instruments made of nickel/titanium. Based on the greater flexibility of files formed from nickel/titanium compared with files formed from steel, proponents of the crown-down method in conjunction with nickel/titanium files assert that such files can better follow the curvatures of a root canal. Additionally, it has been asserted that such files are more likely to stay in the center of the root canal, thereby decreasing the likelihood of ledging or perforating the root canal walls. As set forth hereinbelow in greater detail, each material has its own unique advantages and disadvantages.

12 The ability of a nickel/titanium file to stay in the center is not necessarily desirable, in view of the morphology and perimetrical variety of root canals, and particularly the variety in the upper two-thirds of laminar root canals. In fact when rotation is imparted to an instrument that stays in the center of the canal, the file instrument works simultaneously and indiscriminately on all of the walls within reach of the file. Since root canal walls do not have equal thicknesses in all directions and at all different points along a root canal, some walls can be overthinned or perforated, while other walls remain untouched.
Moreover, because nickel/titanium files are more flexible than steel files, they tend to follow the path of least resistance and therefore cannot be used, in the same way as steel files, to be applied actively and intentionally by the operator. As a result, even when the operator knows the thickness of a particular portion, such as an interference or obstruction which the operator desires to rectify or straighten, the operator lacks the freedom to aggressively drive the file as needed and clean the portions that are difficult to reach. Accordingly, when a nickel/titanium file is used to clean a non-cylindrically shaped root canal, the file moves only at the center of the canal and/or the area of least resistance and fails to remove all of the necrotic tissue.
Figures 15A, 15B, 15C , 15D and 15E depict transverse cross-sections of tooth 190 that has been cleaned in a manner that has resulted in either overthinning of root canal walls, perforation of a root canal wall, excessively weakening of the walls of the tooth or a failure to fully contact all of the canal walls. These problems can be easily caused by the passive, self guiding use of nickel/titanium files with progressively larger tapers in the transition from the first instrument to the next one in the set.
These problems can also be caused by the increasing rigidity, in accordance with the crown-down technique, which prevents the files from being laterally moved to enable the files to clean the entire perimeter of the root canal. The cross-sections shown in Figures 15A-E may be considered independently from each other as being cross-sections from different teeth or from a single tooth such that Figure 1 SA shows two roots 192a and 192b of a tooth 190 while Figures 15B-15E show root canal 194a as the root canal tapers to the apex.
Figure 15A depicts the overthinning that can occur to the furcation walls of root canals 194a and 194b near the bifurcation as a result from the indiscriminate thinning of the distal walls of the root canals by maintaining a file instrument in a central location during working rotation. The resulting boreholes are shown at 196a and 196b while the

13 outlines of root canals 194a and 194b before cleaning are shown in phantom lines. Such overthinning and potential furcal perforation can have devastating results.
The inability to adequately direct a file used in accordance with the crown-down technique based on the practitioner's knowledge of the relative thicknesses of the portions of canal walls is a significant disadvantage of the technique.
Figure 15B shows a lateral perforation that has occurred when a hole was made through dentin 198 and cementum 197 during the cleaning of root canal 194a.
The lateral perforation resulting from the formation of borehole 196a may be obscured from the x-ray due to concavities or curvatures in the root canal. The practitioner may then mistakenly conclude that the root canal has been successfully cleaned without realizing that there is a perforation.
In Figure 15C, the segment shown of root canal 194a was overly thinned during the cleaning of root canal 194a as borehole 196a is shown extending through dentin 198 and into the cementum 197. As mentioned in reference to Figure 15B, the formation of borehole 196a may be obscured from the x-ray view. As a result, the practitioner may not realize that the borehole extends into the cementum and may therefore mistakenly conclude that the root canal treatment has been successful. Infective bacteria that remained in the root canal, perhaps in the portions that were not contacted with the files, as well as toxins produced by the bacteria may then permeate through the cementum and cause infection or other complications.
Figure 15D provides an example of a cross-section of a laminar-type root canal cleaned by the crown-down technique which may result in successful root canal therapy since the instrumentation has not resulted in a perforation and the cementum 197 has not been exposed. Although, problems such as perforations or overthinning have been avoided, Figure 15D shows that large portions of root canal 194a remain untouched despite the change in morphology through the formation of large borehole 196a.
Note that the change in the morphology of the canal shown in Figure 1 SD resulting from crown-down technique instrumentation occurs due to drilling in a passive, circular manner with instruments having gradual and progressive tapers. The failure to contact significant portions of a root canal while forming a large borehole in a root canal as shown in Figure 15B-D is a very typical result of the crown-down technique since most root canals can be characterized as a laminar-type root canal.

14 It would be preferable to avoid the risk posed by failing to contact significant portions of the root canal as shown in Figure 15D. Since the practitioner is prevented from removing and cleaning essentially all pulp material, the practitioner cannot be assured of the reliability of the treatment. Additionally, the practitioner may not suspect that the working instruments have failed to contact every segment of the root canal as use of a set of files with increasingly greater tapers can contribute to a potentially incorrect conclusion that cleaning by such a conventional process has resulted in removing all material from root canal 194a. Further, the x-ray view of tooth 190, as with the step-back technique shown in progress in Figures 13A and 13B, would give the impression that the root canal had been cleaned. It should also be remembered that while rotation of a set of passively actuated files, with increasingly greater tapers, in the center of the canal, in accordance with the crown-down technique, may yield a configuration as shown in Figure 1 SD and result in successful root canal therapy, there is a significant hazard, as shown in relation to the Figures 15A-C, due to the passivity of the instruments when linked to canal diameters and wall thicknesses that are still statistically unknown.
As in the configuration shown in Figure 15D, the configuration shown in Figure 15E may also result in successful root canal therapy -- but only for canals of the wholly tubular type. Although, borehole 196a does not extend through dentin 198 and into the cementum 197, the diameter of the preparation or borehole 196a is nevertheless significantly larger than that of the original root canal was as shown by the phantom lines at 194a. The excessive thinning of the dental wall may resultingly significantly weaken the resistance of the walls to the stress of chewing, and may also cause a fracture of the root.
From the above discussion in relation to Figures 15A-E, it is clear that the actual morphology of the canals is not sufficiently considered when using this method and that the use of files with increasingly larger tapers limits the range of motion of the files. More specifically, due to the use of files with successively larger tapers which therefore are increasingly rigid, each file, if actuated passively, is primarily limited to being rotated without substantial lateral movements guided by the operator. Since the majority of files are of the laminar type, this limitation poses a significant problem. Without the ability to laterally move the files, it is not possible to make contact with every segment of the perimeter of the canal and some portions may receive too much contact.

In any event, if the files are rotated passively in a laminar canal or a canal which has a laminar-type anatomy for the first two-thirds of the canal, the result is a circular opening whose diameter corresponds to that of the file that was used. The file typically stays in the center of the canal during rotation, such that the tip of each file acts like a 5 fulcrum and "ideally" stays in the same position as a rotation point. Since each successive file can move less laterally, each file simply makes a bigger borehole than the preceding file. Accordingly, the files cannot clean a root canal without significantly altering the original anatomy by leaving a footprint or borehole corresponding to the configuration of the instruments used. More specifically, the result is a footprint or borehole with a 10 perimeter that corresponds to the perimeter of the biggest file that extends well beyond the original anatomy of the root canal and yet in most instances does not adequately clean significant portions of the root canal.
As discussed above, the flexibility of the files used in the crown-down technique, which are typically formed from nickel/titanium, prevents the files from being successfully

15 urged against the perimeter or against the various surface features of the root canal. As also discussed above, the flexibility of the files also increases the tendency of the files to remain in the center or at the location where less resistance to movement is encountered.
Accordingly, the flexibility of the files also contributes to the configuration of borehole 196a, which substantially deviates from the original anatomy of the root canal 194a.
There are also other disadvantages to the use of nickel/titanium files. The flexibility of nickel/titanium files increases the likelihood that the file may bend and be deformed upon encountering a hard substance. Since nickel/titanium files are more fragile and more flexible than stainless steel files, the nickel/titanium files can break more easily and unexpectedly than steel files. When a nickel/titanium file instrument is used with a large file diameter the flexibility decreases to the point of being as rigid as stainless steel and yet breaks more easily. More particularly, beyond a certain diameter, the upper halves of larger diameter files are still as rigid as that of steel files while the flexible lower halves of nickel/titanium file instruments are more prone to break.
Additionally, rotation of a file in a canal that has a laminar upper two-thirds exposes the tip of the file to the risk of breaking when the tip of the file is embedded or stuck in a canal whose diameter is smaller than its own diameter! To avoid breaking the tip when it is embedded or stuck in a canal whose diameter is smaller than the diameter of the tip, operators who use nickel/titanium files are advised to employ catheterization

16 in order to obtain a prophylactic widening of the canal, using a series of instruments with increasingly larger tip diameters.
Another disadvantage of nickel/titanium files is that nickel embodied in the alloy may potentially result in an allergic reaction. Further, nickel/titanium files costs about four times as much as steel files and yet nickel/titanium files generally wear out faster than steel files. Nickel/titanium files wear out so quickly that some manufacturers mark their products as being intended for single use only.
Moreover, the crown-down instruments currently available on the market, almost all of which are made of nickel/titanium, in some respects violently conflict with the use of the crown-down method, because, paradoxically, these instruments are smooth in areas where the method requires that they first perform a cutting action. The reason for this deficiency lies in the length of the abrading portion of the instruments, which portion is only 16 mm long and which extends into a smooth portion leading to the handle, onto which rubber stops are affixed, or into which millimeter-based calibration marks are engraved in order to allow visual control of the working depth of the instrument in the canal. For example, note in Figures 13A and 13B that when file 134a is inserted into root canal 162a that the abrading portion 138a is not long enough to contact the dentinal shelves 166, instead the upper portion of the file is smooth shank portion 136a. Since the length of the root canal often exceeds the standard 16 mm length abrading portion of conventional instruments, see Table 1 hereinbelow, we may reasonably ask how an instrument which, according to the crown-down method, is supposed to prepare a canal starting at its coronal third, can perform this task if its coronal segment is smooth!
Table 1/Average Root Canal Lengths Tooth Upper Lower Central 23 mm 20.5 mm Lateral 22 mm 21 mm Canine 26.5 mm 25.5 mm First Premolar 20.5 mm 20.5 mm Second Premolar21.5 mm 22 mm First Molar 20.5 mm 21 mm Second Molar 20 mm 20 mm

17 Obviously, from a review of the average root canal lengths in Table 1, significant segments of a root canal cannot be abraded by standard 16 mm long abrading portions of conventional files and are contacted only by the smooth portion of the files.
Although, the crown-down technique typically enables a practitioner to more efficiently clean a root canal than the step-back technique, they both require the practitioner to utilize many different instruments. The need to frequently change the cleaning instrument results in significant time requirements for cleaning a root canal.
However, careful instrumentation in accordance with either tedious time consuming method does not avoid the problems set forth above in relation to apical perforation, wall perforation, overthinning or failure to clean all of the wall surfaces.
Based on the foregoing observations, methods and systems are needed in the endodontic arts which enable a dental practitioner to remove and clean essentially all pulp material in a root canal requiring root canal therapy.
It would also be an advancement in the endodontic arts to provide methods and 1 S systems that are based on the three-dimensional reality of teeth and do not relate solely to buccolingual x-ray views, thereby enabling a practitioner to remove and clean pulp material in a root canal without compromising the strength of the walls and the apical anatomy.
It would also be a beneficial development in the endodontic arts to provide methods and systems which encourage perimetrical contact of the instruments with the canal walls.
Additionally, it would be an advancement in the endodontic arts to provide methods and systems that enable a practitioner to remove and clean pulp material in a root canal in a manner that is less likely to result in failure due to bacterial contamination, overly thinning the root canal, perforations or due to infected material being pushed beyond the root from the coronal aspects of canals.
Finally, it would also constitute progress in the endodontic arts to provide methods and systems which yield a predictable success rate, minimal risk of breaking an instrument, lower costs, and an abbreviated operating time or an operating time that is at least as efficient as conventional techniques.
SUMMARY OF THE INVENTION
Some of the features of the invention are summarized hereinbelow.

18 Root Canal TerminoloQv Rather than speaking generally of "canals" in connection with operative practice, the present applicant prefers the term "canal element", in order to emphasize that each canal has its own "anatomical personality" with which the operator should be familiar. For example, one canal element may have a perimeter shape which is primarily laminar according to the Latrou classification system discussed in the above section entitled the "Background of the Invention" while another canal element may be tubular. Even in a single tooth which has multiple canal elements, it is important to bear in mind that each canal element has a unique morphology. When refernng to a polyradiculated tooth, which has more than one canal element, such as an upper first premolar, applicant prefers the term "canal apparatus" when referring to a set of canal elements.
Applicant utilizes a terminology based on the methodology disclosed herein.
The term "operative canal" refers to the pathway which starts at the occlusal surface of the tooth, continues with the cameral wall segment and the anatomical canal per se, and finally reaches the foramen. Of course, the anatomical root canal extends from the pulp chamber or the floor of the pulp chamber to the apex.
The operative root canal is divided into three sections or portions which are referred to herein as "the operative coronal portion", "the operative middle portion" and "the apical portion". The operative coronal portion essentially includes the access cavity walls. The operative middle portion is the upper portion of the anatomical root canal while the apical portion is the lower portion of the anatomical root canal. A
typical apical portion is the last or bottom 3 mm of the anatomical root canal.
The terms "operative coronal portion", "operative middle portion" and "apical portion" are unique terms that are distinct from the terminology conventionally utilized to refer to segments of a root canal. In the conventional crown-down method, the canal is customarily divided into the so-called "three thirds", including: the crown, the middle third, and the apical third. In reference to the conventional crown-down method, it is common to use the term "coronal third" to refer to the first part of the "anatomical" canal, originating at the floor of the pulp chamber or the upper limit of the middle third into which a tooth is customarily divided, with a theoretical line at the height of the neck.
Methodolo~v Overview During the root canal therapy, the pulp chamber can be opened to expose the anatomical root canal by any conventional method or instrument. Additionally,

19 conventional methods and instruments can be used to prepare the operative coronal portion. However, unique methods and instruments are used in the operative middle portion while preferably simultaneously abrading the operative coronal portion.
Additionally, after the operative middle portion has been cleaned, unique methods and instruments are used to improve access into the apical portion and to then clean the apical portion.
The present applicant developed the methodology disclosed herein based on the anatomical reality discussed above in the section entitled "Background of the Invention".
By envisioning the canal in which they are operating as starting at the occlusal surface, practitioners can immediately identify any "interferences" or obstructions, as well as any protrusions of enamel, which may be disregarded. As a result, the instruments disclosed herein come into contact with every segment of the canal walls, including the obstructions, in order to achieve anatomical widening and also the rectification or straightening of the first two portions of the canal which include the operative coronal portion and the operative middle portion. This procedure opens the pathway for the preparation of the apical portion of the canal.
The methodology disclosed herein involves the use of distinct instruments in the three portions of the anatomical root canal in different phases such that the root canal is cleaned progressively and sectionally. The instruments) associated with each phase have been designed specifically for that particular phase and accordingly have unique customized characteristics and features. The instruments are described hereinbelow after explaining the procedures for completing each phase.
By cleaning the root canal in sections, the instruments can be adapted to the perimetrical or perimetral anatomy of the root canal. As a result, the entire perimeter or substantially all of the perimeter is contacted and cleaned along the length of the perimeter without substantially altering the configuration of the perimetrical anatomy.
For example, a perimetrical anatomy that was primarily tubular or laminar perimetrical anatomy will be enlarged but will still be primarily tubular or laminar. There will not be a large round borehole in the canal superimposed on the original perimetrical anatomy which corresponds to the diameter of the file that is used; as is the case with the nickel/titanium files that stay in the center of the canal even when the canal is laminas.
Additionally, the invention also enables the practitioner to prepare root canals in accordance with the anatomy of the root canal, even though the practitioner may not have been able to adequately identify the overall anatomy due to the inability to see the root canal as is the case from the mesial-distal view using standard radiography.
Further, the invention also enables the practitioner to adapt to the contours of the root canal of all different types of teeth, by guiding instruments that have been designed to come into 5 contact with every perimetrical segment of the walls.
Inter~erences and Rectification The term "interference" refers to everything in the operative canal that hinders the rectilinear insertion of the instruments used, during the final cleaning phase of the procedure, preparation of the apical portion. The term "rectification" refers to the 10 placement of the operative coronal portion or access cavity on the same axis as the operative middle portion. Rectification is achieved through the removal of interferences from the operative coronal portion and preferably from the operative middle portion of the operative canal as well.
Instrumentation off the Operative Coronal Portion 15 In this phase, the access cavity is created, after elimination of all of the coronal tissue from a carious and weak tooth, and after removal of any infiltrated restoration(s).
The access cavity is also created prior to coronal reconstruction, if considered necessary in order to facilitate the installation of the dam.
It is not necessary to perform a prophylactic cuspidal flattening or cuspidectomy

20 in accordance with the methodology as disclosed herein. However, it may desirable to perform a cuspidectomy with some teeth, particularly lateral postcanine quadrants, in order to create a flat reference plane for the stop, to create an approach nearer to the pulpar horns, to eliminate occlusal contact, and to reduce the masticatory stress on a weakened coronal structure. Weakening of the coronal structure is typically caused by the primary carious process and by the subsequent removal of the roof or top of the chamber due to the need to create the cavity that allows access to the pulp chamber and to the root canal. However, in view of the fact that the top of the chamber is the natural connection between the cuspids, and that after destruction of the top of the chamber, which connects the cuspids, the diameter of the base of the cuspidal columns remains weak in terms of resisting lateral masticatory stress; the operator needs to be assured of the usefulness of performing the prophylactic cuspidectomy on the postcanine teeth.
Apart from avoiding the risk of fractures, the rehabilitative reconstruction of the root canal element may subsequently be facilitated.

21 Instrumentation o~f'tl:e O~~erative Middle Portion The most important part of this phase is the determination of the so-called "working length" of the first two portions of the operative root canal including the operative middle portion and the operative coronal portion. The methods for identifying the working length involve the use of x-rays or videography, performed with the aid of a centering device and through use of the long-cone method. After the working length has been determined, then the proper instruments can be selected for use in the preparation of the operative middle portion.
The working length is determined by measuring the canal axis from the occlusal plane, in order to arrive at the apical limit of the root as indicated on the x-ray. A distance of 3 mm is deducted from the measured length. The result is the maximum working depth that the operative middle portion instruments) should reach. The foregoing calculations also figure in the predetermination of the working lengths for all other instruments utilized in the procedure. The instruments preferably are selected to have files with lengths that are equal to the working length; however, stops may also be used to ensure that the files have the desired working length.
The preparation of the first two portions also involves catheterization.
Additionally, this phase involves the anatomical widening of the perimeter of the operative middle portion as well as the removal of the interferences from the operative coronal portion and the operative middle portions, thereby allowing the rectification of the first two portions of the operative root canal. One of the instrument used during this phase may have a file with an upper portion that is covered with abrasive material or grit such as diamond particles in order to aggresively abrade the upper region of the operative middle portion and the operative coronal portion.
Please note that during preparation of the operative middle portion and rectification of the first two portions, any and all intrusion of the instruments) into the apical portion is avoided. The boundary between the operative middle portion and the apical portion has been estimated to be located between 3 mm and 5 mm from the end of the root canal, as shown on the x-ray. After preparation of the operative middle portion and rectification of the first two portions have been completed, the procedure moves to the third stage, in which the apical portion is prepared.
After the working length has been determined for the first two portion including the operative coronal portion and the operative middle portion, the operator selects an

22 instrument from a set of instruments designed for use in the operative middle portion. The instruments are preferably held in a mini-container whose length is about the same as the identified working length of the instruments.
The contours of the perimeter of the root canal in the operative middle portion are followed as the file of the instruments) is flexed or curved against the surfaces of the root canal and simultaneously moved in a cleaning motion. Since the contours are followed, the perimeter is widened and smoothed but the original shape is not substantially altered.
Preparation of the Apical Portion After the operative middle portion has been cleaned, the apical portion may be cleaned by several different techniques or combinations thereof. One method involves no abrasive instrumentation within the apical portion just appropriate just insertion of appropriate irngation instruments. Since removal of the pulp material from the operative middle portion removes the majority of bacteria in the pulp canal, it has been found that it is not necessary to abrade the apical portion.
Irrigants are delivered into the apical portion to maintain the debris derived from cleaning the root canal in suspension. The debris is then removed as the particles of the smear layer yielded from the action of the files used to prepare the canal may result in clogging the apical portion of the root canal with a plug. After the debris has been removed, the proper preparation and filling of the apical portion of the root canal can be achieved.
By eliminating or minimizing abrasive instrumentation within the apical portion, the potential for complications is diminished. As discussed above in the Background, most errors in performing root canals occur during instrumentation of the root canal. The apical portion is the most delicate part of the root canal and it is the most distally located.
Accordingly, it is highly advantageous to just irrigate and then remove the irrigant and debris, since many complications occur during abrasive instrumentation.
However, in some instances, it may be necessary to improve access into the apical portion such that an irrigation needle can be deployed to deliver irngants to the apical portion. Access into the apical portion is improved by widening, for example, at least the entrance of the apical portion or the entire apical portion.
Alternatively, another method involves the use of a set of instruments designed for cleaning the apical portion in an abrasive manner. Such a method may be initiated directly after the operative middle portion of the operative root canal has been cleaned. However, wo oonass9 PCT/f/LTS00/08122

23 it may be necessary to have two phases of instrumentation within the apical~l portion of the operative root canal including widening and abrasive cleaning of the apical ~l portion. More particularly, it may be necessary to improve the access into the apical I
portion before performing the abrasive instrumentation by widening the transition betweenn the operative S middle portion and the apical portion to enable irrigants to be delivered l into the apical portion.
Before preparation of the apical third is begun by one of the abbove described methods,'the apical and periapical condition of the element is evaluated, , in accordance with the following guidelines. For living or necrotic teeth "without rearranngement of the apex" or apical rarefaction, the instruments) should be kept no closer than l 2 mm from the apex as shown on the x-ray image. Conversely, for necrotic teeth with appical, autolysis, the preparation work may be performed up to a distance of 1 mm from the a apex as shown on the x-ray image. The predetermination of the widening of the canal 1 leading to the apex, and the widening of each root canal for polyradiculated teeth, shhould be made bearing in mind the guidelines for the widening limits set forth in the morl;phometric data provided in Tables 2 and 3:
In most cases, the radicular apex contains the final segment of tithe main canal, which divides into a delta configuration as discussed above in referencee to Figure 3C.
This structure is hard to detect with x-rays. Therefore, the morphology of f the dental apex is unpredictable, and the location of the junction between the cementum anatd dentin in any endodontic apex is random. Likewise random is the hypothetical apical coonstriction thaf can be detected by the most expert professionals. A degree of confidence c~can be obtained through the use of electronic measurement devices in living canals that t have not been treated with liquid medications, but only when the foramen has been pass,sed, in order to be subsequently withdrawn into the canal with a probe instrument. This maaneuver should be avoided in necrotic canals, because of the risk of carrying germs beyond the apex.
The guidelines discussed above should be kept in mind when reddetermining the approximately working length to the apex after the operative middle ponrtion has been prepared. It is necessary to redetermine the working length as the workking length has likely changed due to the instrumentation of the operative middle portionn.

WO 00!74589 PCT~CIUS00108122

24 Instruments The operative middle portion of the operative root canal is cleartned with a first instrument or set of instruments. The root canal, inclduing the apical pportion, is then cleaned with an irrigation instrument.
An optional second instrument or set of instruments can then be us<sed to improve the access into the apical portion to enable irrigants to be delivered into the.e apical portion from an irrigation needle. An optional third instrument or set of instrumernts is provided to abrasively clean the apical portion of the operative root canal after the opperative middle portion of the root canal has been cleaned and after the access into the apiaeal portion has been widened.
Each instrument in the first set of instruments comprises a handle c connected to a file with an abrasive surface or in other words a shaft with tines or an abnrading portion.
Each file has a length such that the operative middle portion of the operautive root canal is cleaned without significantly removing pulp material from the apicaal root portion.
Additionally, each file is designed to have a taper that is larger than thae taper of each preceding file. Each file or shaft has an abrading portion for abrading the suurfaces or walls of the root canal. In contrast to conventional files, as set forth in t greater detail hereinbelow, the abrading portion may extend along the entire length of thhe file to enable the instrument to be used to clean the operative middle portion while als,so abrading the operative corona! portion.
The files of the instruments in the first set are designed such thaat each file has sufficient flexibility to be flexed or curved to urge the abrading porticion against the surfaces of the root canal and su~cient rigidity to apply pressure against t the surfaces of the root canal as the abrading portion of the file is urged against the surfaaces of the root canal and simultaneously moved in a cleaning motion. Additionally, , the files have adequate resilience to avoid being substantially deformed as the file is flexxed or curved to urge the file; particularly the abrading portion, againstthe surfaces of thae root canal.
Each instrument in the optional second set of instruments used 1 to improve or widen the access for the introduction of an irngation needle to the apical portion comprises a handle connected to a file. Each file terminates at a tip wand each file is configured with an abrading portion. Each file has a length sufficieient to at least approximately reach the apex.and to enable the abrading portion of the fifiles to improve the access into the apical portion of the root canal.

Each instrument in the optional third set of instruments used to clrlean the apical portion comprise a handle connected to a file. Each file terminates at a tilip and each file is configured with an abrading portion. Each file has a length sufficicient to at least approximately reach the established apical working limit and to enablde the abrading portion of the files to substantially contact and clean the pulp material in thee apical portion of the root canal. The tip of the file is preferably rounded to prevent ledøging.
These and other features of the present invention will became moree fully apparent from the following description and appended claims, or may be learned by ;~
the practice of the invention as set forth hereinafter.
10 BRIEF I~ESC ftIPTION QF T~iE DRAWINGS
In order that the manner in which the above-xecited and other advvantages of the invention are obtained, a more particular description of the invention briciefly described above will be rendered by reference to a specific embodiment thereof whic.ch is illustrated in the appended drawings. Understanding that these drawings depict t only a typical 15 embodiment of the invention and are not therefore to be considered to be ~
limiting of its scope, the invention will be described and explained with additional specifificiiy and detail through the use of the accompanying drawings listed hereinbelow.
Figure 1A is a perspective view of an x-ray image of several adjaceent teeth taken in vivo.
20 Figure 1 B is an enlarged perspective viewof a root of a tooth showrm in Figure I A.
Figure 2 is a perspective view of an x-ray flm positioned adjaceent to teeth to produce an image as shown in Figure 1 A.
Figure 3A is a longitudinal cross-sectional view of an extracted ldower premolar to show the anatomy of the tooth from the buccal-lingual view.

25 Figure 3B is a longitudinal cross-sectional view of the extracted ldower premolar shown in Figure 3A from the menial-distal view.
Figure 3C is an enlarged longitudinal cross-secfional view of an apexx which divides into a delta configuration having three apical foramina. This configuratioon is presented as a possible alternative to the configuration of the tooth shown in Figure~e 3B.
Figure 4A is a longitudinal crass-sectional view of an extracted upper premolar to show the anatomy of the tooth from the buccal-lingual view.
Figure 4B is a longitudinal cross-sectional view of the extracted upper premolar shown in Figure 4A from the mesial-distal view.

WO 00!74589 PCTTl~JS00/08122

26 Figure SA is a longitudinal cross-sectional view of an extracted !dower incisor to show the anatomy of the tooth from the buccal-lingual view.
Figure SB is a longitudinal cross-sectional view of the extractedd lower incisor shown in Figure SA from the mesial-distal view.
Figure 6A is a longitudinal cross-sectional view of an extracted lower f rst molar to show the anatomy of the tooth from the buccal-lingual view Figure 6B is a longitudinal cross-sectional view of the extracted loower first molar shown iri Figure 6A from the mesial-distal view.
Figure 7 is a cross-sectional view of extracted teeth which have been cut along into transverse cross-sectional segments to show the general categorizatioon of root canal perimetrical anatomies.
Figure 8 is a cross-sectional view of extracted teeth which have '; been cut along into transverse cross-sectional segments to show the anatomy of variousa root canals.
Figure 9A is a schematic perspective view of an extracted maxi:illary right first molar with cutting lines which show the division of the tooth into traansverse cross-sectional segments.
Figure 9B depicts the cross-sectional segments of the molar showHn in Figure to clearly show the variations of the root canals.
Figure l 0A is a perspective view of a prior art instrument cleaning ; a Loath that has been partially cut-away to reveal the inability of the instrument to clean l the root canal.
Figure !0B is a perspective view of a prior art instrument cleaninpg another tooth that has been partially cut-away to reveal the inability of the instrument tcto clean the root canal.
Figure 11A is a longitudinal cross-sectional view of a burr being utitilized to remove the overhanging enamel and dentin above the pulp chamber.
Figure 11B is a longitudinal view of a burr extending through the a enamel and the dentin into the pulp chamber:
Figure I2 is a perspective view of a prior art set of endodontic instrmzments utilized in the step-back technique.
Figure 13A is a longitudinal cross-sectional view of a tooth being g cleaned with a file instrument used in the step-back technique.

27 Figure 13B is a longitudinal cross-sectional view of the tooth shownn in Figure 4A
taken along cutting line 13B--I3B, which shows the portion of the roobt canal which cannot be viewed in viva.
Figure 14A is a longitudinal cross-sectional view of a tooth depicting apical perforation during cleaning of the raot canal.
Figure 14B is a longitudinal cross-sectional view of a tooth depioicting ledging during cleaning of the root canal.
Figure 15A is a transverse cross-sectional view of a tooth depictinpg a root canal cleaned by a prior art technique that has resulted in over thinning of the rcroot canal.
l 0 Figure I 5B is a transverse cross-sectional view of a tooth depictinng a root canal cleaned by a prior art technique that has resulted in lateral perforation.
Figure 15C is a transverse cross-sectional view of a tooth depictinng a root canal cleaned by a prior art technique that has resulted in over thinning of the ra~oot canal.
Figure 15D is a transverse cross-sectional view of a tooth depictinng a root canal cleaned by a prior art technique that has resulted in over thinning of the r~root canal.
Figure 15E is a transverse cross-sectional view of a tooth depictinng a root canal cleaned by a prior art technique that has resulted in over thinning of the raroot canal.
Figure 16A is a perspective view of a set of endodontic instrurnentits for cleaning of the coronal portion and operative middle portion of a root canal.
Figure 16B is an enlarged perspective view of a tip of one of tthe files of an endodontic file instrument shown in Figure 16A.
Figure 17A is a perspective view of another embodiment of a set t of endodontic instruments for cleaning of the coronal portion and operative middle ponrttion of a root canal.
Figure 17B is an enlarged perspective view of a tip of one of x the files of an endodontic file instrument shown in Figure 17A.
Figure 18A is a perspective view of another embodiment of a set t of endodontic instruments for cleaning of the coronal portion and operative middle ponrttion of a root canal.
Figure I 8B is a perspective view of another embodiment of a set t of endodontic instruments for cleaning of the coronal portion and operative middle poDrtion of a root canal.

WO OQl74589 PCTTlUSOQ/08122

28 Figure 18C is another embodiment of a file tip of an endodontic f file instrument shown in Figure 18B.
Figure 19A is a longitudinal view of a tooth with an exposed pulllp chamber.
Figure 19B is a longitudinal cross-sectional view of of the tooth shhown in Figure 19A with a file portion of a file instrument 2UOa inserted into the root ccanal up to the apical portion.
Figure 19C is a longitudinal cross-sectional view of the tooth showrrn in Figure I 9B
taken along cutting line 19C--19C to depict the cleaning of the pulp manterial from the operative' middle portion of the root canal.
Figure 19D is a longitudinal cross-sectional view of a tooth with a 3 file portion of a file instrument 220a inserted into the root canal up to the apical portction and being moved by a handpiece.
Figure I 9E is a longitudinal cross-sectional view of the tooth shownn in Figure 19D
taken along cutting line 19E--19E to depict the file instrument 220d beiring moved by a handpiece to clean the pulp material from the operative middle portion of f the root canal.
Figure 19F is a longitudinal cross-sectional view of the tooth shaown in Figures 19A-C depicting a coronal portion and an operative middle portion of a moot canal which have been cleaned by the removal of the pulp material.
Figure 19G is a longitudinal cross-sectional view of the tooth showrm in Figure 19F
to show that essentially all pulp material has been removed from the coronnal portion and the operative middle portion of the root canal.
Figure 20A is a depiction of a practitioner employing an endodontitic irrigation tip to demonstrate the convenience of employing the angled tip.
Figure 20B is a view of a cross section of a tooth with the apic~,al mot portion being irrigated by the endodontic irngation tip shown in Figure 20B.
Figure 21 is a perspective view of an optional set of endodontic izinstrurnents for improving the access into the apical portion of a root canal.
Figure 22 is a perspective view of an optional set of endodantic irinstruments for cleaning the apical portion of a root canal, Figure 23 is a perspective view of another embodiment of an coptional set of endodontic instruments for cleaning the apical portion of a root canal.
Figure 24 is a perspective view of an additional embodiment of an l optional set of endodontic instruments for cleaning the apical portion ofa root canal.

29 Figure 25 is a longitudinal cross-sectional view of a tooth with a filile inserted into a root canal having a length that is su~cient to reach the apex.
Figure 26A is a longitudinal cross-sectional view of a tooth with a ~ root canal that has been cleaned.
Figure 26B is a longitudinal cross-sectional view of the tooth showrm in Figure 26A
taken along cutting line 26B--26B to show that essentially all pulp matiterial has been removed from the root canal.
Figure 26C is an enlarged transverse cross-sectional view of the t~tooth shown in Figure 26A taken along cutting line 26C--26C to show that the anatomy obf the root canal has not been substantially altered by the cleaning thereof and to show the :
shaping of the canal in preparation of filling the root canal.
Figures 27A-J are transverse cross-sectional views of endodonticc files.
Figure 28 is a longitudinal cross-sectional view of a tooth with a rcxoot canal being cleaned with a file instrument having a file formed by machining a groovve into a metal blank.
Figure 29 is a perspective view of another embodiment of ~ an endodontic instrumezitt.
Figure 30 is a partial perspective view of an endodontic file depicting the tip of the file.
Figure 31 is a partial perspective view of an endodontic f 1e depictinng the tip of the file.
Figure 32 is a partial perspective view of an endodontic file depictinng the tip of the file.
Figure 33 is a partial perspective view of an endodontic file depictinng the tip of the file:
Figures 34A is an enlarged perspective view of x-ray image of a l root canal of a vital tooth without periapical rarefaction.
Figures 34B is an enlarged perspective view of an x-ray image of a a root canal of an infected root canal without periapical rarefaction.
Figures 34C is an enlarged perspective view of an x-ray image of l a root canal of an infected root canal with apical and periapical resorption.
Figure 35 is a view of a system of endodontic tools includingg a first set of instruments for cleaning the operative middle portion of an operative ; root canal, an optional second set of instruments for improving the access into the apiccai root portion and an optional third set of instruments for cleaning the apical root portiaon.
Figure 36A is a cross-sectional view of a tooth after the pulp chaumber has been accessed and before rectification.
5 Figure 368 is a cross-sectional view of the tooth shown in Figgure 36A after rectification and after the operative middle portion has been cleaned.
Figure 36C is a cross-sectaonaI view of the tooth shown in Figureve 36A after the apical portion has been widened.
Figure 36D is a cross-sectional view of the tooth shown in Figuree 36A after the 10 apical portion has been cleaned.
D IL D D T N E D EMBODDIME
The present invention relates to systems and methods for cleani~ing root canals through the removal of pulp material from the mot canals. The inventiopn provides for cleaning the root canal in progressive sections from crown to apex. E'After the pulp 15 chamber is opened and preferably after further preparations, a first instruument or set of instruments is introduced into the root canal to clean the root canal up to 1 the apical root portion. The apical portion is then cleaned by various alternative methoods.
The apical portion is preferably cleaned by deliverying an irngant l into the apical portion and then removing the irrigant along with any debris. In some instaances, a second 20 instrument ar set of instnvments may be optionally introduced to improve t the access into the apical;, portion for introduction of a cannula of an irrigation tip.
Alteternatively, the apical root portion may also be cleaned with a third instrument or set of l instruments.
The invention enables a dental practitioner to remove and clean essentially all the pulp material in a root canal requiring root canal therapy. The cleaning ias achieved in a 25 manner that is safer in terms of over thinning of the root canal and perfonrations and yet requires less instrumentation than conventional techniques.
The techniques described herein for progressive root canal therappy, from crown tai apex, are essentially divided into distinct phases. The phases generally ccorrespond with the particular sections or portions of the operative root canal. After the puhlp chamber has

30 been opened to expose the anatomical root canal, during the root canal thenrapy, as shown in Figure 18, the operative root canal is considered to include the anatorni~ical root canal;
which extends from the pulp chamber or the floor 256 of the pulp chamhber 246 to the apex 254, and the operative coronal portion thereabove. More specificallyy, the operative

31 root canal comprises the operative coronal portion 260, the operative midddle portion 262 and the apical portion 264. Operative coronal portion 260 essentially incluudes the access cavity walls. The operative middle portion 262 is the upper portion of the aanatomical root canal while the apical portion 264 is the lower portion of the anatomical i root canal.
The divisions of the operative root canal are distinguished from thee nomenclature of the anatomical root canal as used to designate the sections before ope~ening the tooth wherein the anatomical root canal is divided into the apical portion annd the coronal portion. The coronal portion of the anatomical root portion is conventionaally defined as the upper portion of the anatomical root canal which terminates at the flooor of the pulp chamber. However, once the pulp chamber is exposed and instruments a are introduced into the root canal, the opening into the tooth should be treated as an exxtension of the operative root canal as it is then a continuous chamber or open tract.
Acccordingly, the access walls are considered part of the operative mot canal and are desisignated as the operative coronal portion or the access portion.
Apical portion 264 extends from the apex of root canal 252 upp to an area of anatomical root canal 252, such that the length of the apical portion is less tlthan half of the length of the anatomical root canal as measured from the apex to floobr 256.
More specifically, apical portion 264 is generally the bottom one-half of the annatomical root canal 252: The actual length of the apical portion varies depending on manny factors such as the type of tooth and the age of the tooth. However, the apical portionn typically has a length in a range from about 3 mm to about 4 mm as measured from thhe apex.
As also indicated hereinabove, operative middle portion 262 is the : top portion of the anatomical root canal 252 and extends from floor 256 down to an area i of anatomical root canal 252, such that the length of the operative middle portion is greaxtter than half of the length of anatomical mot canal 252. More specifically, operative midddle portion 262 is generally the top two-thirds of anatomical root canal 252 as. measure~ed down from floor 256. The length of operative middle portion can be estimated by i~identifying the overall length of the root canal, typically by use of radiography, and tht~en subtracting about 3 mm to about 4 mm from the overall length.
As previously indicated, the three sections are treated in prinmarily distinct sequential phases including: preparation of the operative coronal portion, ~, then cleaning or preparation of the operative middle portion, optionally improving accesss to the apical root portion and finally cleaning of the apical portion preferably by just>t irrigating the

32 apical portion or alternatively. by use of abrasive instrumentation. Examples of instruments intended for use in the cleaning the operative middle pvrtionn are shown in Figure 16A and Figure 17B. Figure 37A and Figure 20B depict insertion oof a cannula of an endodqntic irrigation tip into a root canal to deliver irrigants. Figure :
21 depicts an example of a set of optional instruments designed for use in improving thae access to the apical root portion. Examples of optional instruments intended for use irin cleaning the apical portion in an abrasive manner are shown in Figures 22-24.
The first phase or corona! phase involves exposing the pulp chanmber and also preferably other steps to enhance accessibility into operative middle portionn 262 and also apical portion 264. Accordingly, the corona! or access phase is initiated byy removing the top of the chamber to expose the pulp chamber. This can be achieved,!, for example;
through the use of an instrument such as instrument 120 with bur i22 as shaawn in Figures 11A and Figure I 1B, which is preferably a diamond bur used in conjuncticion with a low or high speed handpiece. However, any suitable instrument can be utilizeed.
After the pulp chamber has been exposed and after the pulp mat~terial has been removed, a tooth appears as shown in Figure 19A wherein a molar 240 is ~
depicted with the overhanging portions of enamel 242 and dentin 244 removed to provicide access into pulp chamber 246. Pulp material 250 still extends within root canal 252 fronm apices 254a and 254b to the floor 256 of pulp chamber 246. Also designated at 248 is t the cementum of the tooth.
During the first phase, it is preferable to remove or reduce dentitinal or enamel protrusion or irregularities that may obscure or hinder access of instrttnments into the remaining portions of the operative root canal. For example, dentinahl shelves depicted in Figure 19A are preferably reduced or rectified to provide greaater access for instrumentation during the subsequent phases. More particularly, inteerferences are preferably removed or minimized such that instruments can be inserted in tithe anatomical root canal in a relatively straight manner. Accordingly, in the subse~equent related drawings, such as Figure 19B, the dentine! shelf is shown removed on thhe canal being cleaned and as not being yet removed above the other canal. Reeetification or regularization can be achieved by any suitable means. It may also be necepssary to widen the tract of the operative corona! root canal: Some dentists may prefer to c~
obtain greater access through a cuspidectomy. Note that during the root canal procedura~e procedure, a rubber dam is typically used to isolate the tooth, which may require in some a instances, the

33 rebuilding of the pulp chamber walls. During this phase as well as thhe others, it is generally necessary to irrigate the root canal with irrigants or a a root canal conditioner/lubricant.
After the operative coronal portion has been adequately prepared, i~ it is preferable to prepare an x-ray image of the tooth to identify the length of the operat~tive root canal in order to determine the preferred working length for the instrument or set c of instruments to be used in the next phase. The preferred working length is preferablyy identified by subtracting about 3 mm from the total radiographic length of the operatitive root canal.
The total radiographic length is preferably derived from a radiograph ~ made using a localizator and a long cone radiographic head.
The second phase involves cleaning or preparation of operative nmiddle portion 262. It may also involve to some extent further rectification of the operatitive coronal or access portion 260 through further removal of any ledges or outcroppings 'which prevent straight and easy access into the operative middle portion 262.
Additionalllly, it may also I S involve some degree of rectification of the upper region or segment of opoerative middle portion 262.
An example of a set of instruments designed for cleaning the ope~erative middle portion is shown in Figure 16A. The set comprises three file instruments 2Q,00 which each comprise a handle 202 connected to a file 204 or a shaft with tines or an abnrading portion.
Each file 204 has a top end 203 where the file joins handle 202. Handle 2002 is connected to top end 203 of file 204 such that movement of handle 202 also movc~es at least top end 203 of file 204 along a common longitudinal axis with handle 202.
The diameter of top end 203a is less than the diameter of top endd 203b and the diameter of top end 203b is less than the diameter of top end 203c. When utitilized to clean the operative middle portion of a root canal, file 200a is first introduced intcto the operative middle portion followed by file instrument 200b and then 200c. Accordingl~ly, the diameter of the top end of each successive file introduced into the operative midddle portion is greater than the diameter of the top end of each preceding file.
Each file terminates at a tip 208 located opposite top end 203. Th'he diameter of each tip 208 in a set of instruments is essentially the same such that thhe diameter of tip 208a is about the same as the diameter of tip 208b and tip 208c. For a example, a set of instruments may all have tip diameters of about .10 mm. A set may als~so be designed such that the instrument intended to be inserted first has a tip diameter of a about .10 mm WO 00/74589 PCT~'IUSflO/08222

34 while the other instruments in the set have a tip diameter of about .l3mnm. A
set with slightly differem tip diameters, such as a set of three or four instruments wNith respective tip diameters of .I O mm, .I0 mm, .13 mm and .13 mm, and in any event t not exceeding 0.15 mzn, is still considered to have substantially constant tip diameters witithin the set as the difference in size is very minor and the diameters do not sequentially inacrease for each instrument. In an alternative embodiment, the tip diameter may vary betweeen instruments in a set such that, for example, the tip diameter of each sequentially irinserted file is progressively larger. As shown in Figure I 6B, which is an enlarged view oof tip 208b; the tips are generally sharp and are configured for at least minimal cutting caapability.
Each operative middle portion file 204 is configured with a suititable abrading portion.209 along most or all of the length of each file. The file is preferahbly configured such that the abrading portion 209 extends along,its entire length as shown l in Figure 16A, however, the files may also have a smooth upper shank portion. Abradinng portion 209 is at least the outer edge of the file 204. The abrading portion of the files l in Figure 16A
I S are formed by twisting a blank such as a rectangular blank.
Figure 17A depicts another set of file instruments 210 which hauve files with a different abrading portion compared to the abrading portion of thea files of file instruments 200. The files 214 have abrading portions 219 that were formedd by machining the files to have knurled surfaces. Abrading porkion 219 as well as abradinng portion 209 and the other abrading or cleaning surfaces disclosed herein are examples of means for abrading the walls of the root canal or root canal surfaces.
Figure 17B is an enlarged view of tip 218a which is shown with a z more rounded configuration than tip 208b such that the tip has essentially no cuttiiing capability.
Figure 18B shows another embodiment of a suitable tip which is desiggned for more aggressive cutting than tip 208b at least as the tip is pushed downward.
Since the tip diameters are essentially equal and since the diameter r of the top end of each successive file introduced into the operative middle portion is I~
larger than the diameter of the top end of the preceding file, the taper of each successive fifile in the set is larger than the preceding file. For example, the taper may range from . .04 to .I3 and increase in increments for each successive file. Each successive file accoDrdingly has an increased surface area for cleaning the root canal. Additionally, as files arcre inserted into a root canal with larger and larger tapers, the rigidity of the upper half of each successive file also increases. The increase in rigidity is; however, minimized by mainntaining the tip WO OOI74589 PCTI~/US00108I22 of each fife at about the same diameter. The flexibility of the lower half remai~ins essentially constant. The rigidity in the upper half is used to remove interferences annd to properly rectify the operative coronal portion 260 and the operative middle portition 262. The consistency in rigidity at the upper half is useful since the lateral perimetrical :1 force applied to the handle is primarily transferred to its upper half or at least the part c closest to the handle, which is the strongest part of the file.
By properly selecting a combination of factors including the diameteers of the files at the top ends and at the tips as well as the material used to form the f less, the files are designed such that each file has sufficient flexibility to be flexed or curve~ed to urge the 10 abrading portion against the surfaces or walls of the root canal and sufficident rigidify to apply pressure against the surfaces of the root canal as the abrading portionn of the file is urged against the surfaces of the root canal and simultaneously moved f in a cleaning motion. Additionally, the files have adequate resilience to avoid being ;
substantially deformed as the file instrument is flexed or curved to urge the abrading poortion against 15 the surfaces of the root canal.
The file can be formed from any suitable material. In forming a suiiitable file, the material is preferably selected in view of the dimensions and design, to yieldd a file having the desired properties with respect to flexibility, resilience andlor rigidit~ty as set forth above. The preferred material for forming files used to clean the operative mniddle portion 20 of root canals is stainless steel. Other metals can also be used such as nic:clcel/titanium;
however, it may be necessary to design the files to have larger diameters thann files formed from stainless steel when using nickel/titanium as nickel/titanium tends to be z more flexible than steel: Alternatively, the files can be formed from suitable non-metal mnaterials, such as a plastic.
25 When the files are formed from tainless steel or a material withh comparable properties, the top end diameter of each file, where the abrading portion termninates, may range from about .25 rnrn to about 2 rnm. However, the diameter will rnnore typically range from about .3 mm to about 1.8 mm and most typically from aboout .4 mm to about 1.5 mm. Additionally, when the f les are formed from stainless steel L
or a material 30 with comparable properties, the tip diameter of each file may range from aabout .06 mm to about .4 mm. More typically, however, the tip diameter will range from aabout .08 mm to about .15 mm and most typically from about .08 mm to about :1 mm.

The length of each file in the set used to clean the operative mniddle portion depends on the length of the tooth being cleaned. More particularly, after l, identifying the length of the root canal from an x-ray image, the length of the file to Vibe used in the operative middle portion is determined by subtracting 3 mm from this identrtified length of the root canal. This length is typically between about 1 S and about 20 r. mm, however, longer files, such as a 25 mm long file, are typically required for canine teetlth. To provide for the different root canal configurations which may be encountered, it l is preferred to have files with lengths ranging from about $ mm to about 35 mm. Howeever, files with lengths ranging from about I0 mm to about 30 mm will be most utilized 1 and files with lengths ranging from about I4 mm to about 26 rnm will be the most frequuently utilized.
After identifying the combined length of the operative middle poortion and the operative coronal portion and after removing the overhanging enamel 242 sand dentin 244, the practitioner selects a file instrument or a set of file instruments as shownn in Figure 16A
or Figure 17A with an appropriate file length. In an embodiment that utililizes no stops, I S the appropriate length corresponds to the combined length of the operative r middle portion length and the operative coronal portion. As shown in Figure 19B, filile 204a of frle instrument 200a is then inserted into root canal 252 down through opaerative middle portion 262 without extending substantially into apical portion 264. Each fifiie 204 of each file instrument 200 in the set of instruments shown in Figure 16A has a length that is only sufficient to enable the file to contact the operative middle portion andd the operative coronal portion of the root canal. Accordingly, a file instrument.t such as file instrument 200a or a set of file instruments such as 200a, 200b and 200c coomprises a first endodontic instrument means for anatomically removing and anatomi~ically cleaning essentially all pulp material from the operative middle portion withouut significantly extending into the apical root portion.
The file length of files 204 enables a practitioner to aggressi~ively clean the operative middle portion without worrying that the instrument will overlrly thin the root canal, perforate the apex or that cleaning will cause extrusion of materi;ial through the apex. Another benefit of cleaning the operative middle portion first is z that the apical portion is then generally more accessible and easily cleaned. Addititionally, since instruments are selected for use in cleaning the operative middle portion wvhich have files lengths that do not permit entry into the apical portion, the likelihood c of jamming or breaking a tip of an instrument while working in the confined space of the appical portion is prevented.
By instrumenting in the operative middle portion and the operative coz~ronal portion before the cleaning the apical portion, the practitioner can use an instruurnent that is relatively flexible compared to the conventional instruments. As shown in ~
Figure 19C, which is a cross-sectional view taken along cutting line 19C--19C of t tooth 240- in Figure 19B, file 204a of file instrument 200a is sufficiently flexible to be flexe~ed against any surface of operative middle portion 262 or operative coronal portion 2660 and yet is sufficiently rigid to remain flexed against the surface during a cleaning motition such as a longitudinal motion, a rotational motion or a reciprocating rotational motionn. The file is also sufficiently resilient that substantial deformation of the file does not ocGCUr due to the forces experienced during cleaning of the pulp material from the root canaal.
File instrument 200a is shown in Figures 19B and 19C being ; moved in a longitudinal movement or up and down movement as well as being rotated wlvhile file 204a is flexed or arched to urge the file against the root canal surfaces. Aas shown, the configuration of the files used to clean the operative middle portion, and preferably the operative coronal portion as well, enable a practitioner to move the files around the perimeter or from side to side to contact the perimeter. Further, since the f file is moved around the perimeter, the file has more than one center of motion during chleaning of the operative middle portion of the root canal, such as a pivot point or center oof rotation, as the tip of the file or at least a part of the abrading portion does not gene:erally remain primarily in one position. This is in sharp contrast to prior art methods whiach limited the practitioner to essentially rotating a conically shaped file to yield a cone shopped borehole.
Due mainly to the configuration of the files, each file is able to flexx such that its abrading portion is urged against root canal surfaces while the instrument i:is rotated and moved in a cleaning motion. Accordingly, the contours of the operative conronal portion and the operative middle portion can be used during their cleaning by a praactitioner as a guide for the movements of the instruments as the files are pushed against thhe surfaces of the root canal and simultaneously moved around the perimeter or periphenry of the root canal until the practitioner has reached the beginning location of the cleaningg and shaping process. Far example, in root canals that are primarily noncircular, the files s can be urged along one side and then along the next side wall in a maryer such that : he resulting cleaned andi;shaped root canal is generally widened but still primarily noncirc~cular. In other WO 00174589 PCTA'/US00108122 words, there is essentially no borehole that obviously corresponds to the shape of the file as the instruments have been moved in conformance to the anatomicala shape of the operative middle portion.
Due to the ability to move the file as discussed; the anatomy of t the root canal remains substantially unaltered despite the cleaning of essentially all pulp r material from the operative middle portion. The understanding that the final anatomy is ~
guided by the shape of the original anatomy enables a practitioner to taZOre confidently unrge a file such as file 204a against all surfaces of root canal 252 and aggressively clean all c of the surfaces of operative middle portion of the root canal since the likelihood of overl'ly thinning the root canal or causing lateral perforations as shown in Figure 15A-C and 1 Figure 15E is diminished. The assurance of the safety of the methodology is further l;boistered by a general knowledge of wall thickness variations.
Another advantage of the configuration of operative middle portionn instruments, such as f 1e 204a shown in Figures 19B and 19C; is that the file can simultanneously abrade both operative coronal portion 260 and operative middle portion 262. The files can simultaneously abrade both portions as each file has an abrading portion aklong the entire length of the file. A primary benefit of simultaneously abrading both portionns is the ability to further straighten the operative coronal portion while cleaning the opeerative middle portion.
Use of files inthe operative middle portion which have an abradingg portion along their entire length is in contrast to files formed in accordance with ISO
statandardization.
ISO standardized files have abrading portions of up to 16 mm and the renmainder of the file is a smooth shank. Examples of such files are shown in Figures 13A-1-B
and 14A-B.
Since such conventional fzles are inserted down to the apex, it is generally r.not possible to abrade any portion beyond the anatomical root canal. Since such convventional files frequently fail to remove interferences extending from the access or root chharnber above the anatomical root canal, as shown in Figure 13A, the instrument must bend around the interferences, thereby further increasing the likelihood of wall perforations,, overthinning and failing to clean significant portions of the canal. It especially increases ~ the likelihood of iatrogenic modifications resulting from the tip of the file.
The instruments in the sets shown respectively in Figure 17A and i in Figure i at 210a-c and at 220a-d are each depicted with a stop 140. Stops such as ~
stop 140 may be used to ensure that the length of the portion of the fIe inserted into thee tooth is such WO 00/74589 PCT/~/USOOIO$122 that the file does not extend significantly into the apical root portion.
Figura~e 19D depicts the use of stop 140 on instrument 220a. The advantage of using such a stoop is that less sets of instruments are needed in order to have a set that can be utilized in teeeth of varying lengths. Note that while stops are shown which have a thickness of about 1 r mm, the stops may have varying thickness. Also, the stops may also be positioned such tha~at one or more stops are positioned adjacent to the handle such that movement is not possisible since the stops already abut the handle. For example, in Figure 18A two stops are l positioned on shank portion 226a of file 224a. One of the stops has a thickness of 2 mm vwvhile the other has a thickness of of 1 mm as shown respectively at 141 and 140. Note ' that stop 141 abuts handle 222a to prevent any possible movement. All of the stop disclosed herein are examples of stop means for limiting the operative middle portion instrumnent means to insertion into the operative corona! portion and the operative middle portition.
When a stop is used, the length of the root canal from an x-ray l image is first identified and hen the length of the root canal above the apical root portion l is determined by subtracting 3 mm from this identified length of the root canal. An instruvment is then selected that has a length that is slightly longer than the determined lenggth of the root canal down to the apical portion. Note that this determined length is the conmbined length of the corona! portion and the operative middle portion.
it may also be advantageous to use a stop such as stop 140 to more a easily flex the file against the root canal surfaces. More particularly, using an instrumetrnt with a stop alters the curvature of the file since the portion above the file is also flexeda. This results in a different flexed configuration or pivot point so that greatest pressure l is applied at a higher part of the root canal than when an instrument is used withouizt stops.
The desirability of applying pressure in such a manner depends on the particula.~ar tooth. Note however that if an instrument is used without a stop as in Figure 19B and Figure 19C the portion of the file that is flexed against the root canal can also be used to abbrade sections thereabove by merely moving the file upward as it is flexed.
Although the file instruments used to clean the operative middle poortion, can be manually moved, they are preferably used in conjunction with an instrumennt designed for movement of endodontic file instruments such as a conventional denhtal handpiece instrument. The handpiece 500 shown in Figure 19D and in Figuree 19E at 500 corresponds with the handpieces disclosed in Serial No. 09!425,849 annd Serial No.
09/425,857. Handpiece 500 has a head 600 with a head element 610 that I holds a chuck WO 00174589 PCTTlUS00/08122 700. One of the advantages of handpiece 500 is that rim 614 of head e)rlement 610 is essentially coplanar with any bottom surfaces of head element 610. Th'his essentially coplanar configuration is particularly useful since rim 614 is used as a stopp as it is rested on the coronal surface of tooth 240'. The ability to use rim 614 as a stop a eliminates the 5 need for rubber stoppers. Although, it is not necessary to use a stopp when using instruments adapted for use with the handpiece disclosed in the aboove-identified applications, a stop is shown being used in Figure 19D in order to illustrtrate the use of stops with handpieces in general. Accordingly, it is understood that thhe instruments disclosed herein can be used with any conventional handpiece.
10 When rotated by a handpiece, the file instzvment such as instrumennt 220a shown in Figure 19D can be continuously rotated in one direction only or the file i~instrument can be rotated in a reciprocating motion such that the file instrument rotates s for example, clockwise for half of a revolution and then counterclockwise for half a r revolution. A
reciprocating motion is preferred as such motion enables the file to altenrrrately engage 15 material 250 and the walls of the operative middle portiow of the root canaal in a manner that removes material 250 and to then rotate in the opposite direction succh that the file less aggressively engages material 250 and the operative middle portion walalls, depending on the file design. Accordingly, rotating file instrument 220a in a reciproocating motion minimizes: breakage of file 224a when file 224a encounters a surface that pre~events rotation 20 of file instrument 220a in a direction that enables cleaning and removal of f material 250.
Handles 202a-c, 212a-c, and 222a-d are latch-type handles designeed for coupling with a handpiece. Note that although instrument 200a has a latch-t~.ype handle, a handpiece is not depicted in Figure 19B and Figure 19C being used to a move the file instrument, in order to optimally view the movement of the instrument. AAn example of 25 a handle adapted for manual manipulation is shown in Figure 28 at 312.
Moved of the file instrument with a handpiece is preferred as hand milling is more dift~ficult and time consuming. A f 1e instrument can also be vibrated to clean the coronal poortion and the operative middle portion. File instrument 220a shown being utilized inn cleaning the coronal portion 260 and the operative middle portion 262 of tooth 240' in 1 Figure 19D is 30 part of a set of instruments depicted in Figure 18A at 220a-d. File instruuments 220a-c have the same dimensions as instruments 200a-c and are similarly configur~red except that each of file instruments 220a-c has a shank portion 226. The shank portitions 226a-d at respective op ends 223a-d provide for easy movement of stops 140. ,BAs previously WO 00!74589 PCTT/US00/08I22 indicated in reference to the set of instruments depicted in Figure 16A a at 200a-c, the instruments used to clean the corona! portion and the operative middle pq~ortion may be configured without a smooth shank portion. If the instruments have a shannk portion it is preferably; about 2 to about 4 mm in length and is preferably about 4 mrn. .
Note that the instruments in Figure 17A depict relatively short shank portions that are aabout 2 mm in length while the instruments in Figure 18A depict longer shank portion thhat are about 4 mm in length. The shank portions depicted in Figurel7A, Figure 18A, Figgures 18C have a slight taper; however, the shank portions may also be non-tapered litike the shank portions of the instruments shown in Figure 23 and in Figure 24.
The set of instruments shown in Figure 18A also includes an aggra~esive abrasion instrument 220d. After the operative corona! portion and the operative nmiddle portion have been cleaned and shaped through the use of instruments such as abrasiaon instruments 220a-c then the root canal can be more aggresively shaped with instrurne~ent 220d.
Like the other instruments in the set, instrument 220d has a file 2244d with a shank portion 226d at its top end 223d; however, the file 224d has a unique abnrading portion 229d. File 224d, more particularly abrading portion 2294, has an abrasive a upper section 225d for aggresive abrasion and a lower section 227d that is relatively less s abrasive than the upper section. The upper section 22Sd has abrasive particles positionedd thereon while the lower section 2274 is not coated with abrasive particles but is twisted c or fluted. File 224d is formed by twisting the lower section and positioning an abrasive a on part of the smooth or non-fluted upper section of the file above the lower fluted sectici.on. All of the smooth or non-fluted upper section may be coated so that there is no shannk portion or a portion may be left uncoated so that there is shank portion as shown in 1 Figure 18A at 226d.
The advantage of using an instrument with a file having an uppe:er section with abrasive particles such as instrument 220d as shown in Figure 18A or insvstrument 220d' as shown in Figure 18B is that the corona! portion and the top of the opoerative middle portion can be more aggresively shaped while shaping the bottom of the opperative middle portion less aggresively. The usefulness of an instrument such as instrumenht 220d to clean or shape with greater abrasiveness at its upper half and less abrasiveness at~t its lower half is depicted in Figure 19E which is a cross-sectional view of tooth 240' wivith instrument 220d being moved by chuck 700 of endodontic handpiece head 600. The L upper abrasive particle coated section 225d enables the removal or reduction of dentitinal or enamel WO 00!74589 PCT/UUS00108122 protrusions or irregularities such as dentinal shelves shown at 266 in Figure 1'19D that may obscure or hinder access of instruments into the operative root canal. In manny instances.
use of an instrument such as instrument 220d eliminates the need for rectification of such protrusions with a rectification instrument.
Note that tooth 240' shown in Figure 19E is nearly identical to toothh 240 shown in Figure 19C, the only difference is that tooth 240' does not have an outitcropping of dentin to divide the canal like that identified as 244 in Figure I9C. Tooth ~
240' appears without such an outcropping to clearly illustrate that the depicted movenments of the instruments in Figure 19C and in Figure 19E occur in accordance withh the present invention irt the operative middle portion of all teeth. Stated otherwise, suchh movements enable the file to follow the contours of the root canal and are utilized in tithe operative middle portion of all root canals.
The,abrasive particles are preferably diamonds. The application.
inmpregnating, coating or attachment of the diamond coating may be achieved by any cconventional method. For example, the abrasive particles may be electrolytically appplied, plated, sintered, bonded with adhesives or impregnated into the surface of the.
smoobth part of the file. Examples of preferred methods of positioning abrasive particles includes forming the coating by electro-deposition or by direct or indirect sputtering.
Although, diamond is the prefer ed material other materials may be opptionally used instead of or in addition to diamond. Examples of suitable materials for usse as abrasive particles include: carborundurn'T'' or other suitable refractories of silicon caarbide; fused alumina and other materials; aluminum oxide; natural aluminum oxide such aas corundum;
alumina ceramics; glass; silicon dioxide or silica; silicon carbide; boron nitricide; and other comparably hard materials.
The abrasive particles may form a coating, Iayer or covering with a any suitable thickness and the particles may have any suitable average size. More pat~ticularly, the thickness of the abrasive particle coating is preferably in a range from abouut 100 ~m to about 700 Vim; more preferably about 200 ~cm> and most preferably about~t S00 ~cm. A
preferred average particle size is in a range from about 30 ,um.to about 350 ~.,um. A more preferred average particle size is in a range from about 50 ~m to about 2560 ,um.
Files with abrasive particle coated upper sections also preferably haave a smooth shank portion below the handle. The smooth shank portion preferably hay a length of about 2-4. mm. The upper abrasive particle coated section is preferably no ~
greater than about half of the length of the file extending from the handle and is mare pnreferably less than half of the length of the file extending from the handle. lnstrumennts having an abrading portion with an upper abrasive particle coated section and a lower r less abrasive section are 'preferably configured such that the length of the upper abrasive pparticle coated section is about the same as the Lower less abrasive section. The Lengths c of such upper abrasive particle coated sections are accordingly in a range from about 4 to a about 10 mm in length and are preferably in a range from about 4 to about 8 mm in lenggth.
Lower fluted section 227d is an example of a lower less abrasive ~ section.
The lower less abrasive section may also be configured Like the knurled surfacce of abrading portions 219 or any other surface which abrades less aggresively than the us~se of abrasive particles. The lower section may also alternatively be smooth like the shanhk portion and terminate at a tip so that it has essentially no abrasive ability.
The file of the instrument preferably has the abrasive particle coatinng on only the upper section of its abrading portion as shown in Figure 18A, Figure 18B a and in Figure 19E; however in some embodiments, the entire abrading portion may boe coated with abrasives. Additionally, the upper section that has abrasive particles may ahlso be twisted or fluted as shown in Figure 27J so that the entire abrading portion is twi:isted or fluted while only the upper section is covered with abrasive particles. Similanrly, the entire abrasive portion may be configured as shown in Figure 17A with a knurled 1 surface while the upper section is covered with abrasive particles. Further, the abradingg portion may have any appropriate configuration and have an upper portion with abrasives particles that enable more aggresive abrasion in the operative coronal portion of the roobt canal and in the top region or segment of the operative middle portion of the root canaal.
An instrument such as instrument 220d or 220d' is preferably paart of a set of instruments such as the sets shown in Figure 18A or 18B such that the stet includes at least one abrasion instrument and one aggresive abrasion instrument.:: The set of instruments shown in Figure 18B includes only the last two instruments of f the set shown in Figure 18A. Note that the only difference depicted between instrumaent 220d and instrument220d' is that instrument 220d has a smooth tip 228d for less agggresive cutting while instrument 220d' has a pointed tip 228d'. Pointed tip 228d is shown inn greater detail in Figure 18C.
Advantages of using a set such as instruments 220c-d' instead of a lalarger set such as instruments 220a-d is that the set is less expensive and is simpler to use ~: However, it WO 00/74589 PCTfilUS00/08122 may also be preferable to use a set with three, four or-more instrurnent~ts to clean the operative coronal portion and the operative middle portion with very gradutial increases in rigidity so that the aggresiveness of the abrading is gradually increased as thhe instruments are sequentially utilized.
As indicated above, while instruments 220a-c have shank pportions these instruments have the exact same dimensions as instruments 200a-c.
Accordiiingiy, the files of instruments 220a-c all have essentially the same length and tip diameter r and also have sequentially larger top end diameters and tapers. Aggresive abrasion insbtruments 220d and 220d', however, are each shown with a file having a length, tip dianmeter, top end diameter and taper that is essentially the same as that of file 224c.
Althouugh, the file of the aggresive abrasion instrument pxeferably has the same dimensions as tithe instrument previously inserted into the root canal, other configurations may also be a utilized. For example, the aggresive abrasion instrument may have a larger top end dtiiameter and a larger taper than the file of the instrument introduced previously in the , sequence or a 1 S smaller top end diameter and a smaller taper:
Instruments such as instruments 220d or 220d' may be used alone a or as part of a set to remove and clean essentially all pulp material from the operative ccoronal portion and the operative middle portion. Instruments such as 220d or 220d' as wwell as sets that includes such instruments are additional examples of first endodontic instttrument means for anatomically removing and anatomically cleaning essentially all pulp ma~ateriai from the operative middle portion without significantly extending into the apical r~root portion.
Figure 19F shows a cross-sectional view corresponding to the x-i-ray view after pulp material 250 has been removed from the operative middle portionn 262 of root canal 252a and after the surfaces of root canal 252a have been shaped too yield shaped surfaces 268a of the root canal. Figure l 9G is a longitudinal cross-sectionnal view taken along cutting line 19G--19G of tooth 240 in Figure 19F which clearlrly shows that essentially all pulp material has been removed and cleaned from ope~erative middle portion 262.
Removal of pulp material 250 from operative middle portion 26'02 removes the majority of bacteria in the pulp canal since the majority of bacteria in ann infected root canal is typically located in the operative middle portion. Not only is the gr~reatest volume of bacteria in the operative middle portion but it is also believed that the cooncentration is greater in the operative middle portion. Since a certain minimum threshold r must generally be reached far complications to arise due to microbial presence in a root ccanal, removal of the pulp material in the operative middle portion significantly reduces thhe likelihood of such complications.
By removing the majority of bacteria before cleaning the apical pportion there is also less likelihood of exposing the surrounding tissue to bacteria due to ooverly thinning the root canal, perforation or extrusion of material from the canal. The greaatest likelihood for the occurrence of complications such as over thinning of mot canal wal~lls, perforation or extrusion of material from the canal is in the apical portion. The apical~l portion is the most likely site for such complications as apical portions are more compleex and delicate 10 compared to the operative middle portions of teeth: Since such complicaations are most likely to occur in the apical portion, it is highly beneficial to have the matiterial removed from the operative middle portion in order to minimize the amount of maiaterial that can come out of the root canal to cause problems. For example, in the evernt of an apical extrusion far less septic material may be expressed during instrumentationu in accordance 15 with present methodology than if the apical extrusion occcured as a result t of cleaning in accordance with conventional methods wherein files are inserted to the .
apical portion before cleaning the operative middle portion. As a result, removal of tithe majority of bacteria before cleaning the apical portion increases the likelihood of successful root canal therapy in several ways compared with conventional methods.
20 To minimize the possible introduction of bacteria, it is preferable t to utilize a kit.
The kits preferably support a set of several instruments with identical lenggths positioned to be easily grasped and preferably in an antimicrobial solution.
It should be noted that when there is an atresic root canal, it is pra~eferable to use EDTA in a hydrosoluble gel and leave the composition in the canal for a a few minutes.
25 Similarly, for necrotic canals, it is advisable to work in a sodium hypochl<lorite saturated environment. For canals with living pulp, it is advisable to work in ann environment saturated with 10% hydrogen peroxide.
As previously discussed, the majority of bacteria in an infectedd root canal is typically located in the operative middle portion. Accordingly; it has been f found that after 30 the operative middle portion has been cleaned in an abrasive manner effectrtive root canal procedures are completed by cleaning the apical portion without abradiiing the apical portion. More particuariy, after removing and cleaning essentially all pulp omaterial from the operative middle portion of an operative root canal in conforrnaance with the WO 00174589 PCTTIUSOOl08122 anatomical shape of the operative middle portion by flexibly moving an instrrument within the operative middle portion, the root canal procedure can be effectively c completed by merely irrigating the apical portion of the root canal and then removing thne irrigant and debris. This eliminates the possibility of exposing the surrounding tissue tdo bacteria due to overly thinning or perforating the apical portion of the root canal and rnninimizes the possibility of extrusion of material from the canal. Since such complicatitions typically occur during abrasive instrumentation within the apical portion due to thae delicate and complex structure of the apical portion; the elimination of the need l for abrasive instrumentation in the apical portion is highly advantageous. Further, this s methodology is particularly advantageous in light of the prior cleaning of the root canal aboove the apical portion.
Another benefit of cleaning the apical portion by irrigating the apicahl portion with an irrigant and then removing the irrigant and debris from the apical portion, is the reduction in the number of instruments needed to complete the proceedure. More particularly, since instruments adapted for abrading the apical portion are r'not necessary but are optionally used, the total instruments used in performing root canal l procedures is reduced.
In addition to cleaning the apical portion, irngation is used to maint<~tain the smear layer in solution within the apical portion, thereby avoiding smear layer aaccumulation.
Additionally; it is useful to maintain the debris derived from cleaning the a root canal in suspension to avoid filling the apical portion of the root canal with a plug.;: If the apical portion becomes filled, there is an increased likelihood that the progresasion may be prevented or that debris may be pushed out of the tooth.
In addition to conventional irrigation devices; a preferred irrigatition device is shown in Figure 20A and Figure 20B which is a syringe 790 coupled to ~ an irrigation tip 720. While such irngation devices are preferred, any conventional irriggation tip and associated delivery device such as a syringe may be utilized.
Note that due to the angled configuration, as shown in Figt~ure 20A and Figure 20B, a practitioner is readily able to place the cannula 760 extendiiing from neck 740 of angled tip 720 into a root canal 782 of a patient's tooth 780 whhile holding a syringe 790 coupled to tip 720 at an angle with respect to the patient's ~
mouth. This angled configuration enables the practitioner to more easily insert cannula c or needle 760 into a root canal and to move the tip within the root canal.

WO 001'14589 PCT~TlUS00/08122 As hown, the practitioner is able to strategically, conveniently posuition stop end 744 on the rim of the occlusal surface of a crown and orient cannula 760 irin a controlled manner within root canal 782. Note that neck 740 has a stop end 744 width a distal flat face 746 which is configured to act as an integral stop to prevent penetrationn into the root canal ?82 of endodontic irngator tip 720 beyond the length of the portion off cannula 760 extending from stop end 744 of neck 740.
The working length of cannula 760 is the portion of cannula 760 eextending past stop end 744 of neck 740. By using an irrigator tip having a cannula with tithe appropriate .
working length and a neck 740 having an integral stop end 744, the practiticioner is able to avoid apical perforations: For example, as shown, a tip may be selected v~with a cannula length which extends within about I millimeter above the apex 784, whilee stop end 744 prevents cannula 760 from penetrating too fax. This permits the calculat~ted delivery of fluid all the way to apex ?84 without perforating apex 784. Thus. beecause of'stop end 744 and a cannula 760 having an appropriate working length, the praractitioner can confidently place cannula 760 in close proximity to apex 784 withouut perforating apex 784. Note that it is preferred to slowly withdraw cannula 760 while ddeliverying the irrigant. Although, tip 720 is preferred, other conventional endodontic irnggator tips may also be utilized and conventional stops may also be utilized.
Another preferred irrigation tip is the Endo-Eze~ irrigator tip soldd by Ultradent Products, Inc which has a straight cannula or needle. Examples of suitablole Endo-Eze~
irngator tip include those which have a 27 gauge cannula (.40 mm out t diameter), 30 gauge cannula (.30 rnm outer diameter) and a 31 gauge (.25 mm outer diamneter). In some circumstances, larger needles may be used. In any event, the needle : or cannula is preferably sufficiently small to avoid binding within the cannula and a also to enable backflow for flushing the apex.
The irrigator tips and other suitably shaped narrow tubular devices such as pipettes, are referred to herein as apical portion cleaning instruments. Thae irrigator tips disclosed herein and other suitably shaped narrow tubular devices, are examnples of means for cleaning the apical root portion, after the pulp material has been essentitially removed from the operative middle portion. More specifically, the irrigator tips arcre examples of means for cleaning the apical root portion by deliverying an irrigant into t the apical root portion.

w0 00/74589 PCTh/USOO108122 In addition to syringes, such irrigator tips may be coupled to a Strcropko device.
Syringes and the Stropko device are examples of delivery devices. These s same devices are examples of irngant delivery devices when coupled with an irngator tipp that enables the delivery devices to easily access the root canal. While these irngant deliiivery devices are particularly useful when cleaning the apical portion, note that all of tthese irrigant delivery devices may also be used in irrigating the canal at any appropriate tinme during the root canal procedure. Note that syringes and other delivery devices such ~ as a Stropko delivery device are examples of means for deliverying irrigants and/or removing irrigants and any remainig debris via the irrigator tip or means for cleaning the apical i1 root portion.
Pipettes are a less preferred alternative to the use of irrigation tips as a apical portion cleaning instruments to deliver irrigants into the root canal. Such conventitional pipettes are well known in endodontistry and are used to deliver irrigants by squeezixing part of the pipette. The pipettes may be prefilled or used with a separate reservoir or~r container of lubricant: A pipette is an example of an integral irngant delivery device whilile an irrigator tip coupled to a syringe or a Stropko device is an example of a separable irn~igant delivery device. Such integral irrigant delivery devices are additional examples n of means for cleaning the apical root portion or more specifically, means for cleaning thhe apical root portion by deliverying an izxigant into the apical root portion.
These same irrigant delivery devices are typically used to remove thhe irrigant and any remaining debris. For example, the syringe may be used to aspirate these irrigant and any remaining debris out of the apical portion. Similarly, a pipette may apphly appropriate suction to remove the irrigant and any remaining debris. The endodontic irririgator tip may also be coupled to other conventional aspiration devices. Other irrigant remnoval devices include conventional paper points. When the irrigant and debris have been nremoved; the tooth appears as shown in Figure 20B at 780.
Although, the irrigant preferably is capable of dissolving or disruptiiing soft tissue remnants to permit their removal, the irrigant may be any suitable liquid suach as water or various alcohols. More particularly, although some degree of debridementlt is preferred, any fluid may be used to flush debris from the root canal. General ; examples of appropriate irrigants include hydrogen peroxide, primarily for use in the cagnals of living teeth, or sodium hypochlorite, primarily for the canals in necrotic teeth. 7 The preferred irrigant is the aqueous sodium hypochlorite solution sold as ChlorCid~ J by Ultradent Products; Ine which contains about 2.5-3% NaOCL: The irngant may also c be a chelator or calcium remover such as EDTA solutions or citric acid solutions. A
prefrferred chelator is sold as File-Eze~ by Ultradent Products lnc. which is a 19% EDTA ' water soluble viscous solution. File-Eze~ is a preferred chelator as it is also a lubric~cant: Another example of a commercially available chelator is the Pulpdent EDTA soI>lution said by Pulpdent Inc.
In some circumstances, it may be necessary to improve the access i3into the apical root portion before cleaning the apical root portion of the root canal. Morale particularly;
it may be beneficial or necessary to widen the tract of the root canal to proveide access for thin irrigation needles. This may be achieved by widening the transitions between the operative middle portion and the apical portion or by widening the entire a apical portion such that a thin irngation needle can access the apical portion as needed.
TThin irrigation needles typically have a diameter no smaller than about .30 mm so it may bbe necessary to increase the diameter of portions of the root canal up to about .35 mm or even up to about .40 mm, particularly within the region of the boundary between the ope~erative middle portion and the apical root portion. Note that the diameter need only be .
lightly larger than a thin irrigation needle in order to provide adequate access. Improvising access into the apical portion not only enables such irrigation needes to have move as nneeded, it also reduces he likelihood that the thin irrigation needes will be blocked.
The diameters of many root canals within the region of the boundar~ry between the operative middle portion and the apical root portion and even within the apidcal portion are alreadly large enough to enable irrigation needles to deliver irrigants as far ads is necessary.
However, even though it is preferred not to widen the diameter within the a~apical portions or even the tops of the apical portions, it is often necessary to do so.
Ref~fer to Tables 2 and 3 in Example 1 for some average root canal diameters as measured 2 >_ mm from the apex of each root canal. In Table 2 and Table 3, the largest average diameteer in the apical portion for a particular type of tooth measured in the sampling was 0.54 r mm while the smallest average was 0.18 mm. Note that the tip diameter of operative nmiddle portion instruments, as indicated hereinabove, typically range from .06 mm to .x.40 mm, more typically from about .08 mm to about .15 mm and most typically from aboout .08 mm to about .1 mm. In light of the apical portion diameters that are likely to be enncountered, as indicated in Table 2 and Table 3, and the tip diameters of the instruments s used to clean the operative middle portion just above the apical portion, it is apparent thaat widening is often necessary inorder to enable irngation needles to adequately deliver l irrigants.

WO 00194559 PCTT/US00/0$122 5~
It is not necessary for the entire apicaLportion to be widened up to aabout .35 mm or about .40 mm; just enough of the apical portion should be widened so thfaat the irrigants can be delivered as needed. However, the length of files used to widen the ~
apical portion is preferably sufficient to at least approximately reach the apex.
Accordinggly, the tap of the abrading portion may be flared to enable the upper area of the apical.l portion to be widened up to about .40 mm while the tip diameter which is at or neaar the apex is preferably significantly smaller. Note that in addition to abrading at least t the top of the apical portion, it may also be necessary to widen the diameter at the region s o~ the base of the operative middle portion with the widening at the top of the apical ponrtion.
I O Note that before widening the apical portion of the root canal, it is.s preferable to make a predetermination of the desired diameter. This predeterminationn is preferably made in light of average diameters, wall thicknesses, etc. for the particuiilar root Banal being cleaned. As indicated hereinabove, Table 2 and Table 3, hereinbelo~w in Example 1, provide a sampling of such morphometric data.
I S An example of an optional set of instruments designed for improvising the access into the apical root portion is shown in Figure 21. The set compririses four f 1e instruments 270a, 2?Ob, 270c and 270d. Each file instrument comprises s a handle 272 connected to a file 274. Each file 2'74 has a top end 276 where the file joinns handle 272.
When utilized to widen the access into the apical root portion of a root caanal; file 270a 20 is first introduced followed sequentially by file 270b, 270c and then 2700d. Each file terminates at a tip 278 located opposite top end 276. A file instrumennt such as file instrument 270a or a set of file instruments such as 270a, 270b, 270c and 2770d comprises a second endodontic instrument means for optionally, improving access i~into the apical root portion after the pulp material has been essentially removed from t the operative 25 middle portion by the first endodontic instrument means.
Each file 274 of the file instruments designed for improving access;s to the apical root portion of a root canal is configured to have an abrading portion 279 t along at least a portion of the length of file 274. The entire length of each file 274 can t he configured with an abrading portion 2?9, however, abrading portion 279 preferably ~
extends from 30 tip 278 part way upward towards top end 276 such that the remainder c of file 274 is relatively smooth. More particularly, each file is preferably configured width an abrading portion along less than about half of the length of the file and more preferabbly about one-third of the length between tip 278 and top end 276. Accordingly; the abraading portion WO 00174589 PCTrfIUS00/08122 may have any suitable length such as 3 mm or 10 mm; however, the abradifing portion in a preferred configuration is about 5 mm or about 6 mm. The abrading ponrtions as well as the tips can have a similar or identical configuration to the abrading portrtions and tips of the files disclosed herein for cleaning either the operative middle portidon of the root canal or the apical root portion. However, the abrading portions and tips a are preferably rounded as shown in Figure 21.
As indicated above, the length of a file such as files 274x, 274bb and 274c is preferably sufficient such that when the file is inserted into the root canal 1 the tip can at least approximately reach the apex and the abrading portion 279 of the filee can improve l 0 the access into the apical portion of the root canal. Although files used tao improve the access into he apical root portion may be long enough to approximately reach the apex, the files can be used to improve the access as long as the files can reach the bottom of the operative middle portion and the top of the apical root portion. Such filile lengths are typically within a range from,about 8 mm to about 35 mm, more typically inn a range from 15 about 14 mm to about 35 mm and most typically in a range from about 12 mnm to about 33 mm. The length of the abrading portion is generally within a range from ahbout 1 rnm to about 3 5 mm, more preferably in a range from about 2 mm to about 16 r mm and most preferably in a range from about 3 mm to about 6 mm. The abrading portionn is preferably long enough so that the entire apical portion can be abraded as well as at leaast the bottom 20 of the operative middle portion. Note that stops such as stop 140 may altlternatively be utilized with instruments used o improve the access into the apical root pportion.
In an optional set of instruments used to improve the access into a an apical root portion, the file tips of the instruments preferably all have about the same~e diameter as shown in Figure 21 at 278x-d. The diameter of the tips is generally within l a range from 25 about .06 mm to about 1 mm, however; the tips preferably have a diarneterr of about .08 mm. In a less preferred embodiment, the tip diameter of each file may r also increase sequentially.
As shown in Figure 21, the diameter of the abrading portions 2799x-d increases from the tips 278x-d towards the tap of the abrading portions. The diaameter of the 30 abrading portion at the top is preferably within a range from about .1 mm too about .4 mm and is more preferably in a range from about .2 mm to about .35 mrn. . As shown in Figure 21, each successive file has an abrading portion, 279x, 279b, and 2279c which is successively larger in diameter at the top of the abrading portion than the abnrading portion of the preceding file. Accordingly, a set may have files with abrading porticions having the following respective top diameters: about .2 mm, about :25 mm. about .3 r. mm and about .35 mm. Each abrading portion in such a set has a different taper as is shnown in Figure 21.
Figure 21, however, also shows that the taper of the smooth or slshank portions above the abrading portions may have essentially the same taper so that tithe taper of the shank portions remains essentially constant as the dii~erent files in the set anre sequentially inserted. However, the shanks portions may have any suitable c configuration:
Accordingly, the diameter at top end 273, in addition to being greater thane the diameter of the abrading portion, can also be equal to or less than the diamete:er of abrading portion 279 or tip 27$.
As mentioned above, the apical portion may be alternatively cleane~ed by abrading the apical portion. Typically, the instruments used to optionally improve tithe access into the apical portion, the apical portion access instruments, have the same 1 lengths as the instruments optionally used thereafter to abrade the apical portion so that thhe entire apical portion is first widened and then cleaned in an abrasive manner. Thae instruments, however, have very different tip diameters and tapers along their respeactive abrading portions. The apical portion access instruments generally have much smaller rip diameters and much greater tapers than the instruments used to abrasively clean the ~
apical portion for safe widening of apical portions. Refer to Example 2 and the accompaanying Figures 36C-D for a discussion of specif c instruments utilized and to observe the altlteration of the apical portion after the apical portion widening phase and the apical ponrtion cleaning phase.
Before the apical root portion is abrasively cleaned, it is preferaable to obtain further x-ray images while an instrument is inserted into a root canal to c determine the desired working length of the instrument. In establishing the working lenggth, the state of the apex and the periapical tissues should also be considered. The states mnost frequently shown in radiography are shownin Figure 34A-C wherein the apical portionn of root canals 354a-c of roots 3S2a-c are depicted. Figure 34A depicts a root canal 354a oof a vital tooth without periapical rarefaction as shown by the normal border with the t bone at 356a.
Figure 34B depicts an infected root canal 354b without periapical rarefactition as shown by radiolucency 358b. Figure 34C depicts an infected root canal 354c wivith apical and periapical resorption as shown by radiolucency 358c. if the practitioner r identifies the condition of the root canal as being that depicted in Figures 34A or Figure ;
34B, then the working length of an instrument used to abrasively clean the apical root F
portion is in a range from about 0 to about 2 mm less than the distance from the occlusal l surface to the radiographic apex of the tooth. However, if the root canal condition is infifected and has apical and periapical resorption as depicted in Figures 34C, then the apicaal root portion may be abrasively cleaned up to about 1.5 mm or about 0.5 mm from thee radiographic apex or more particularly about 1 mm.
An example of an optional set of instruments designed far removing s and abrasively cleaning essentially all remaining pulp material from the apical portion of a a root canal is shown in Figure 22. The optional set comprises three file instrument~ts 280a, 280b and 280c. Each file instrument comprises a handle 282 connected to a fifile 284. Each file 284 has a top end 283 where the file joins handle 282. When utilizeed to clean the apical root portion of a root canal, file 280a is first introduced into the apicual root portion followed by file 280b and then 280c. Each file terminates at a tip 288 loc~cated opposite top end 283. A file instrument such as file instrument 280a or a set of filile instruments such as 280a, 280b, arid 280c are referred to herein as apical portion cleaninng instruments and are examples of means for cleaning the apical root portion by abrading ~
the apical root portion. More specifically, such instruments and sets of instruments as disisclosed herein are examples of third endodontic instrument means for optionally, abrasivehly cleaning and removing essentially all remaining pulp material from the apical root portioz~n after the pulp material has been essentially removed from the operative middle portion. .
Note that the means for cleaning the apical root portion, after the pulp material has beeen essentially removed from the operative middle portion, by deliverying an irrigant iainto the apical portion and also the third endodontic instrument means are both examples;s of means far cleaning the apical root portion after the pulp material has been essentially r removed from the operative middle portion.
Tips 288a-c can have any configuration, however, tips 288a-c pr~referably have minimal cutting capability to decrease the likelihood of ledging. An examphle of a suitable configuration for tips 288a-c that is designed to minimize the cutting abilit3ty of the tips is that of the ;round tip shown in Figure 17B.
Each file 284 of the file instruments designed for abrasively cleaning ; he apical root portion of a root canal is configured to have an abrading portion 2$9 al~Iong at least a portion of the length of file 284. The entire length of each file 284 can be caonfigured with WO 00174589 PCT/,'/US00/08122 an abrading portion 289, however, abrading portion 289 preferably extends (from tip 288 part way upward towards top end 283 such that the remainder of file 284 is relatively smooth. More particularly, each file is preferably configured with an abradding portion along less than about half of the length of the file and more preferably about c one-third of the length between tip 288 and top end 283. The abrading portion 289 can haave a similar or identical configuration to the abrading portion of the file or files used i to clean the operative middle portion of the root canal or the files used to improve the acocess into the apical root portion.
The length of an optional apical portion abrading file such as files s 284a, 284b and 284c is ufficient such that when the files are inserted into the root canal.l the tips can at least approximately reach the apex and the abrading portion 289 of t)the files can substantially contact and abrasively clean the pulp material in the apical portioon of the root canal. Such file lengths are generally within a range from about 8 mm to abbout 35 nun, more typically in a range from about 14 mm to about 35 mm and most typicalilly in a range I S from about I2 mm to about 33 mm. The length of the abrading portion is gene~erally within a range from about 1 mm to about 35 mm, more preferably in a range from l about 2 mm to about 16 mm and most preferably in a range from about 3 nizn to about E 6 mm. Note that stops such as stop 140 may alternatively be utilized with instrume~ents used to abrasively clean the apical root portion.
The diameter of the abrading portion is generally within a range fropm about .06 mm to about 1.4 mm. As shown in Figure 22, each successive file has ; an abrading portion, identifed as 289a-c, which is successively larger in diameter at thhe top of the abrading portion than the abrading portion of the preceding file.
The diameter of the tips 2$8a-c of each optional apical portion abradiling file may be increased incrementally such that each sequentially utilized abrasive cleaninpg instrument has a slightly larger tip diameter than the preceding instrument as shown in Fr<igure 22 and Figure 23 or the tips diameters may be about equal in diameter like the tilips shown in Figure 21.
Additionally, the taper of files 284 from tip 288 to the top end of f the abrading portion may be constant as shown in Figure 22. The taper may also increasee from file to file Like the files shown in Figure 21 or like irtstrcunents shown in Figure

35 inn optional set 470. The diameter at top end 283 is shown being greater than the dianineter of the wo oonass9 Pc~Tmsoa~osiza abrading portion. However, the diameter at the top end of the file can also i be equal to or less than the diameter of abrading portion 289 or tip 288.
The abrading portion 289 of each file 284 of file instruments 280U is formed by twisting a blank so as to form a spiral. Files having such spiral-type abradinng portions are 5 preferred. The abrading portion 289 preferably has few spirals such thattt the action of abrading portion 289 against the walls or surfaces of the apical portion of f the root canal is relatively gentle. Such an abrading portion is less aggressive as fewer spnirals results in tines that have a wider angle.
Figure 23 depicts an alternative embodiment of files configured fifor optionally, 10 abrasively cleaning the apical portion of a root canal. The set of optionaal instruments depicted in Figure 23 comprises three file instruments 290a, 290b and 2990c.
Each file instrument comprises a handle 292 connected to a file 294. Each file 29x4 has a shank portion 296 above an abrading portion 298. Shank portion 296a has su~bstantiaily the same diameter along its length and the diameter of shank portion 296a is a~approximately 1 S the sarpe as the diameter of shank portion 296b and 296c. The diameteer of abrading portion 298a is essentially constant along the length of abrading portion 2988a. Similarly, abrading portions 298b and 298c also have substantially constant diameters. .
The diameter of abrading portion 298b is larger than the diameter of abrading portion l 298a and the diameter of abrading portion 298c is larger than the diameter of abrading ;
portion 298b.
2f Figure 24 depicts an additional alternative embodiment of files cconfigured for optionally, abrasively cleaning the apical portion of a root canal. The set oof instruments depicted in Figure 24 comprises three optional file instruments 300x, 30UOb and 300c.
Each file instrument comprise a handle 302 connected to a file 304. Each n file 304 has a shank portion 306 above an abrading portion 308. Shank portian 306a has.s substantiaily 25 the same diameter along its length and the diameter of shank porirrion 306a is approximately the same as the diameter of shank portions 306b and 306c. FEach abrading portion 308 extends from each respective shank portion 306 with a shape thnat is generally elliptical. Additionally, the width of each successive abrading portion 308 l is larger than that of the preceding abrading portion. More specifically, the width ofeaach successive 30 abrading portion is larger at its midpoint.than at the midpoint of the prececding abrading portion.
Figure 25 depicts file 284a inserted into apical portion 264 of rooot canal 252a.
The apical root portion file instruments are generally moved in a different pattern Sb compared to the operative middle portion file instruments due primarily too the different perimeter anatomies of the two portions. A root canal generally becomes mo.ore cylindrical towards the apical portion such that a root canal that has a perimeter anpatomy that is essentially elliptical in shape within the operative middle portion tapers to a an essentially cylindrically shaped perimeter anatomy within the apical portion.
An elliptical perimeter anatomy typically requires that the practitiopner move the file around the perimeter and/or flex the rotating file against the surfaces s or walls in a milling motion such that the tip is moved to many locations around the peErimeter. Due to the more cylindrical anatomy ofan apical root portion, it becomes much ldess necessary, and virtually impossible to flex a rotating file in a milling motion. It is generrally adequate to merely rotate the file within the apical root portion andlor move v the file in a longitudinal motion. More specifically, after the file reaches the apex or approximately reaches the apex, the file is preferably moved upward while simultaneously t being rotated, and it is withdrawn in order to be cleaned before being reintroduced.
Since file 284a is generally not moved around the perimeter as inn cleaning the operative middle portion, the center of motion, such as the center of rotations, of file 284a generally corresponds with the center of the mot canal. In contrast, the centiter of motion when the operative middle portion is cleaned is at various locations as the 3 file is moved around the root canal.
The files used to optionally clean the apical root portion in an abrasivve manner can be designed for primarily longitudinal movement, rotational movement or c combinations thereof. Since it is generally not necessary to flex a file when abrasivelyy cleaning the apical root portion as the apical root portion is typically rounder than other r sections of a root canal, apical root portion files need not necessarily have the same propperties as the operative middle portion files in terms of flexibility, rigidity and resilience. 7 The files used to abrasively clean the apical portion are, however, preferably sufficiently flexxible to adjust to the anatomy or structure of a root canal in a manner that enables the tip p of the file to reach the apex. The files also preferably have sufficient rigidity to apply pre~essure against the walls or surfaces of the root canal as the abrading portion of the file is L urged against the walls of the mot canal and simultaneously moved in an abrasive cIeaningg motion even after the file has moved throughout the length of the root canal.
Additionallyly, an optional file configured for abrasive use in an apical root portion preferably has adequuate resilience 5?
to avoid being substantially deformed as the file passes through a root canaal and also as the abrading portion is applied against the walls of the root canal.
Figure 26A depicts a longitudinal cross-sectional view of tooth 240 aafter both root canals 252a and 252b have been cleaned. Figure 26B depicts a cross-sectitional view of tooth 240 taken along cutting line 26B--26B in Figure 26A: From the viriew shown in Figure 26B, it is clear that essentially all pulp material 250 has been removwed from root canal 252a.
Figure 26C is a transverse cross-sectional view of root canal 252aa taken along cutting line 26C--26C in Figure 26A through cernentum 248 and dentin 2444 to depict the configuration of the cleaned and shaped root canal. The view shown in Figuure 26C shows in phantom lines the original configuration of the perimeter of the pulp canalll 252a and the configuration of the cleaned and shaped walls 268a.
While the root canal is cleaned, it is also generally simultaneousvly shaped for subsequent filling with a filling material such as gutta percha. Cleaning and s shaping aroot canal, such as pulp canal 252a, to yield a cleaned and shaped root canal, suuch as shaped walls 268a, generally necessitates the widening of portions of the pulilp canal and smoothing some contours of the pulp canal to yield a wider and smoothaer canal. The amount of dentin removed during the cleaning and shaping is preferably no nmore than just sufficient to adequately shape the root canal for subsequent filling.
Because the perimeter of the root canal is followed during cleaningg and shaping of the root canal; particularly the coronal portion and the operative middhle portion; the original anatomy of the root canal or shape of the perimeter is substantiall~ty maintained.
Accordingly, when the original perimeter is, for example, generally elliptical such as the cross-sectional shape of pulp canal 252a, the resulting cleaned and shaped r~raot canal has a perimeter that is still generally elliptical such as shaped walls 268a ~ as shown in Figure 26C. Similarly, if the original shape of the perimeter of a root canal 1 as seen from a transverse cross-sectional view, such as the anatomies or perimeter cconfigurations shown in Figures ?, 8 and 9B, is generally circular, laminar or tear shopped, then the .
cleaned and shaped walls will also be generally circular or tear shaped. Inn other words, the original anatomy of the root-canal controls the shape of the resultingg cleaned and shaped anatomy due to the cleaning techniques enabled by the present invvention.
In contrast, prior art methods yield a final anatomy that is dictatedd by the shape of the instrument. As shown in Figures 1 SA-F, prior art methods result in an a anatomy with WO OOI74589 PCT~'/US00/08122 a significant footprint from the instrument without even cleaning all of thee perimeter of the root canal. In addition to failing to fully clean the root canal, the tooth c can be overly thinned, perforations may result or the tooth may be unnecessarily wesakened when cleaned by such prior art methods.
Figures 27A-27J are transverse cross-sections of exemplary filews that can be utilized to clean the operative middle portion, to optionally improve the ;
access to the apical root portion or to optionally clean the apical root portion of the rooot canal in an abrasive manner. Each file has a different abrading portion. All of the files irin combination with their:respective abrading portions disclosed herein are examples t of means for removing and cleaning of pulp material as the file instrument is operatitively moved.
Additionally, each abrading portion disclosed herein is an example of a meanns for abrading a root canal.
Conventional file designs can also be utilized within the scope oof the present invention. Accordingly, the files are not limited to the designs shown in Fig~,rures 27A-27J.
The files preferably, however, are configured in a manner such that when thae potential for breakage is minimized. For example, a file with a square cross-section may~y be preferred over a triangular cross-section as the file with a square cross-section has as greater mass and is accordingly less likely to break. Additionally, a file configured ;
with tines or extensions having wide angles are generally preferred over those with marrow angles.
However, the preferred tine configuration depends primarily on the partic~cular use as in some instances it is desirable to aggressively cut while in others the root t canal can be passively cut. When it is more desirable to aggressively cut, it may be :
preferred for example to utilize a file with relatively narrow tines.
Figure 273 depicts a file 3l0 with a generally square-shaped trannsverse cross-section and truncated corners 312. Abrasive grit or abrasive material 314 ~ is located on truncated corners 3I2. Similarly such abrasive grit can be located around a fifile having any cross-sectional shape and be an effective abrading portion. The abrasive gririt may be any of the abrasive materials discussed above such as diamonds, The transverse cross-section of a file shown at Figure 27A correspponds to a file as shown in Figure 17A. In Figure 28, a file instrument 320 is shown cleani~ing operative middle portion 160 of a root canal. Instrument 320 has a handle 322 connecbted to file 324 formed by machining a groove into a metal blank. Note that handle 322 l is adapted for WO 00/74589 PCT/f/US00108122 manual use, however, a handle such as handle 202 designed for mechanical .l rotation may also be used.
Figure 29 depicts another embodiment of a file instrument shownn at 330. File ixistrument 330 has a handle 332 which is particularly adapted for use with a a mechanical S instrument: The file instruments of the present invention can, however, be ~
utilized with any suitable handle configuration. All of the handles disclosed herein are exaamples of end means for grasping and operatively moving a file in an abrasive action.
File instrument 330 further comprises a file 334 which is preferably ~ used to clean the operative middle portion. File 334 has an abrading portion comprising pprotrusions or barbs 335 at the upper end of the file and a combination of barbs 3355 and knurled surface 33? at the lower end. Figures 30-33 are depictions of various tips oof files within the scope of the present invention.
EXAMPLES OF THE PREFERRED EMBODI~~1TS
Testing was conducted to identify some of the anatomical characteristics of different teeth. The results of this testing are reported in Example 1. ~
Additionally, Example 2-4 are hypothetical examples presented solely to illustrate some a embodiments of the present invention. Note that reference is made in Example 2 to FFigure 35 and Figures 36A-D. The hypothetical examples are not to be construed as limititing the spirit and scope of the invention as these hypothetical examples were produced uin furtherance of reducing the present invention to practice.
xam 1 Table 2 and Table 3 presented hereinbelow provide data regarding tlihe anatomical characteristics of root canals of different teeth. More particularly, average nmeasurements are provided of the canal diameters and the wall thicknesses of root canals.s at a location 2 mm from the apex of each root canal. A practioner should bear tlthese average measurements in mind when optionally widening the apical portion or cleanizing the apical portion. Note that the roots of the first molars are referenced by their posvition with the abreviations m,v, d, and 1 for the terms mesial, vestibular, distal and linguual.

Table 2lRoot Canal Anatomical Characteristics MaxillaryNumber DistanceAverageAverage AverageAverageAverageAverage of Teeth Roots From Mesio-DistalVestibulo-VestibularLingualMesiaiDistal the ExaminedApex Canal Distal Wall Wall Wall Wall Canal DiameterDiameterThicknessThicknessThicknessThickness Central20 2 mtn 0.39 0.38 0.93 1:12 0.91 t.05 mm mm mm mm mm mm 5 Incisors Lateral20 2 mm 0.23 0.39 0:87 1.09 0:81 0.77 mm mm mm mm mm mm Incisors First 20 2 mm 0.25 0.20 0.88 0.65 0.95 0.80 mm mm mm mm mm mm Premolars 10 Second 20 2 mm 0.27 0.23 1.15 0.99 0.99 0.86 mm mm mm mm mm mm Premolars First 25 2 mm 0.18 0.32 1.04 1.07 0.73 0.82 Molar mm mm mm mm mm mm m-v Root First 25 2 mm 0.21 0.23 0.87 0:81 0.89 0.85 Molar mm mm mm mm mm mm 1 S d-v Root First 25 2 mm 0.23 0.22 0.68 0.85 0,85 1.03 Molar mm mm mm mm mm mm i Root fable 3/Koot Canal Anatomical (;haracteristics MandibularNumberDistanceAverage AvetageAverageAverageAverageAverage 20 Teeth of From Mesio-DistalVestibulo-VestibularLingualMesialDista!
the Roots Apex Canal Distal Wall Wall Wall Wall Canal Examined DiameterDiameterThicknessThicknessThicknessThickness Central 30 2 mm 0.22 0.40 1.06 1.12 0.22 0.72 mm mm mm mm mm mm Incisors Lateral 25 2 mm 0.22 0.28 0.76 0.71 0.73 0.67 mm mm mm mm mm mm Incisors 2$ Gattines30 2 mm 0.29 0.3b 0.95 0.10 0.71 0.77 mm ttun mm mm mm mm First 30 2 mm 0.39 0.38 1.21 1.25 0.94 0:94 Molar mm mm rnm tnm mm mm .

m Root First 30 2 tnm 0.23 0:54 1.23 1.28 0.87 0.92 Molar mm mm mm mm mm mm d Root t t 1 1 t I 1 WO 00/745$9 PCThJUS00108122 Exam 1 This example describes, in relation to Figure 35 and Figures 336A-36D, an exemplary system and method for cleaning a .root canal after the root caanai has been properly accessed. After a tooth has been identified as requiring root canaal therapy, an x-ray image is obtained in order to determine the state of health of a tooth aas well a5 the structure and anatomical characteristics of the tooth. After all carious tissue has been removed and any old fillings have been infiltrated, a darn is installed.
Before the instruments designed for use in the operative middle pportion or the apical portion of the root canal are utilized, the pulp chamber must be propperly opened I O so that adequate access can be gained to the anatomical root canal. Access s is gained by removing the _ top of the pulp chamber, preferably with an appropriate c diamond bw instrument. The contents in the pulp chamber are then removed witlth the aid of appropriate irrigants. Examples of appropriate irrigants include hydroggen peroxide, primarily for use in the canals of living teeth, or sodium hypochlorite, prinmarily for the canals in necrotic teeth. If desired a cuspidectomy may be performed.
It is then preferable to remove or reduce dentinal ar enamel pnrotrusions or irregularities such as dentinal shelves, that may obscwe or hinder access off instruments into the operative root canal by rectification of such protrusions with ann appropriate instnzment which preferably utilizes diamonds for abrasion. Figure 36A
de(epicts a tooth 740 before the removal of dentinal shelf 266 above root canal 252a. Dotteed line 550 in Figure 36A depicts the desired realignment through rectification in ordeler to provide greater access for instrumentation during the subsequent phases. Rectifieied root canal 252a depicted in Figures 36B-D after ubsequent phases shows that rectificication would enable an instrument to be inserted in a relatively straight manner though t the operative coronaI portion 260 and the operative middle portion 262. Although, aan instrument would need to flex within the apical portion 264 of root canal 252a due to l its curvature, the required flexing is minimized as a result of the removal of dentinal sheelf 266 above root canal 252a. Since the apical portion of root canal 252b is essentisially straight, rectification of dentinal shelf 266 above root canal 252b would also enable aan instrument to be inserted up to apex 254b through the apical portion 264 in an essentitially straight configuration.
The progressive phases depicted in Figures 36A-D are similar to the pphases shown in Figures 19A, I9F, 25 and 26. For example, Figure 36A depicts the samne phase as is WO 00!74589 PCTICJUS0010$122 shown in Figure 19A. Figures 36A-D, however, better depict the changes c of the shape of pulp canal 252a after each phase. The same numbers are used for the elemnents of tooth 740 as are used for tooth 240: Note that pulp material 250 is not shown in Fipigures 36A-D
so that the changes to pulp canal 252a are clearly visible after each phase.
PAs discussed hereinbelow, Figure 36B-D respectively depict root canal 252a of tooth 740 aafter cleaning operative corona! portion 262, after widening apical portion 264 and after cleaning apical portion 264:
After any necessary rectification, the working length is determinedi for the files used to clean the operative middle portion. The appropriate working length ins determined by radiographically identifying the length of the operative root canal and thern subtracting 3 mm from the length identified from the x-ray image. It is necessary to suubtract 3 mm from the overall x-ray length in order to compensate for any distortions in thee x-ray image and to avoid interfering with the apical portion while the operative middle ponrtion is being prepared. After identifying the length of the root canal of a tooth and deteEermining the 1 S working length of the files to be used, instruments can then be selected vwvhich have a length such that essentially all pulp material can be anatomically cleansed from the operative middle portion of a root canal without significantly removing pulp mnaterial from the apical root portion.
Figure 35 depicts three sets of instruments identified at 410, 440 anad 470 which are used to prepare a root canal. The sets of instruments identifiedrespectitively at 410, 440 and 4?0 are respectively used to clean the operative middle portion,; to improve access into the apical portion and to clean the apical root portion.
(,~nerative ~ fiddle Portion Phase and Itela~d Sets o,;flnstrumerrts Tables 4A, 4B and 4C presented hereinbeIow describe the dimensvions of three different set of instruments which can be used to clean the operative middllle portion in different teeth depending on the particular operative root canal length.
Theese three sets are preferably sold as part of a kit. Although, the kit includes several sets of f instruments, only one set of instruments is typically used for cleaning the operative midddle portion.
The practitioner selects from several sets in the kit depending on the particulxlar length of the operative corona! portion and the operative middle portion: The instrumeants in Tables 4A, 4B and 4C have lengths which are respectively 16 mm, 17 mm and 20D mm.
In this example, the set of operative middle portion instruments selelected for use in a tooth is the set presented in Table 4C due to the combined length of tithe operative w0 00!74589 PCTT/LTS00/08122 corona! portion and the operative middle portion of the operative root canaal.
The set of instruments for cleaning the operative middle portion detailed in Table 4CC
corresponds with the set of instruments shown in Figure 35 at 410. Since only one set oof instruments is used to clean the operative middle portion only one set is shown in Fig~;ure 35 at 410.
Table 4AlOperative Middle Portion Instruments (16 mm)i) Instc'ument\Total AbradingShank Tip Diameter Shank Abrading at Number Length PortionPortionDiameterthe top PorortionPortion of the of the Length Length Abrading DiaumeterTaper File (Lz + (LO (LO (DO Portion (I(D<) La) (D3) 1 16 mm 14 mm 2 mm .10 .38 mm .50 .OZ
mm 7 mm 2 16 mm 14 mm 2 mm .13 .69 mm .70 .04 mm D mm Table 4B/Operative Middle Portion Instruments (17 mm)~) InstrumentTotal AbradingShank Tip DiameteratShank Abrading Number Length Portion PortionDiameterthe top PonrtionPortion of of the the .ength Length Abrading DiarameterTaper File (Lz (L~) ~-3) (D~) Portion (~D<) + L3) (D3) 1 17 mrn 15 mm 2 mm .10 .40 mm .50 .02 mm D mm 2 17 mm I5 mm 2 mm .10 .70 mm .70 .04 mm D mm Table 4C/Operative Middle Portion Instruments (2O mm) InstrumentTotal AbradingShank Tip Diameter Sh;hankAbrading at Number Length PortionPortionDiameterthe top PonrtionPortion of of the the FileLength Length Abrading DiarameterTaper (I-z (L,) (L,) (D,) Portion (I(Da) + Lz) (D,) I 20 mm 18 mm 2 mm .10 .46 mm .50 .02 mm D mm 2 20 mm I 8 2 mm .13 .85 mm .90 .04 mm mm D mm As shown in Tables 4A, 4B and 4C, the operative middle portion ilinstruments in the sets may have exactly the same tip diameters or may have tip diameteters which are essentially the same. More particularly, the instruments in the set detaileed in Table 4B
both have a tip diameter of .10 mm while the instruments in the sets prese:ented in Table 4A and Table 4C have a tip diameter of either .10 mm or .13 rnm. Tn each s~set, the second instrument has a greater taper than the file of the first instrument.

WO OUI74589 PCTA'/USOO/DSI22 As indicated above, set 410 corresponds with the set presented in 7 Table 4C.
As shown, instruments 410a and 410b have files 414a and 414b. Each filde has a shank portion 416 which tapersto an abrading portion 419 configured like convenntional K-files and terminating at a tip 418. Smooth shank portion 416 may be used to a accommodate stops to adjust the working length of file 414. Note that the file of eaach instrument detailed in Tables 4A, 4B and 4C has a 2 mm smooth portion or shank port:~tion above the abrading portion. Handles 412a and 412b are respectively positioned on s smooth shank portions 416a and 416b. These handles are configured for attachment too a handpiece.
The sets of instruments presented in Table 4A and 4B have a similar appoearance to set 410, however, the files of the instruments in Table 4B have an abrading porticion configured to correspond with Hedstrom-type files.
The operative middle portion instruments in each set are formed f from stainless steel. The instruments all have sufficient rigidity to apply pressure agaiunst root canal surfaces as each instrument is flexed or curved against root canal surfaces and simultaneously moved in a cleaning motion. Each instrument also has adeqquate resilience to avoid being substantially deformed as the instrument is flexed or curvc~ed to urge the abrading portion against root canal surfaces and as the instrument is si~imultaneously moved in a cleaning motion. Accordingly, a practitioner can move the instrxument around the perimeter of the operative middle portion of the root carnal using the econtours of the operative middle portion as a guide for the movement of the instrument~t such that the original anatomy is enlarged and not significantly altered.
After set 410, as detailed in Table 4C, is selected, the pulp chamber iris flooded with an irrigation fluid or filled with a chelating lubricant gel; if the canal is.s atresic. The instruments in set 410 are then attached to a handpiece to move the instrumnents in either a rotating or reciprocating motion. These instruments can also be rnannually moved.
Instrument 410a and then 410b are then sequentially urged against the root ccanal for about one minute in conformance with the anatomy of the root canal. More paarticularly, the instruments are applied to the perimeter of the canal, acting on any prontuberances or jagged edges in order to rectify the first two portions, the operative middHle portion and the operative coronal portion, while still conforming to the anatomy of thhe canal:
After cleaning the operative middle portion, the root canal may aappear as does root canal 252a of tooth 740 Shawn in Figure 36B. Figure 36B shows that t dentinal shelf 266 has been fully rectified. The other contours of root canal 252a have t been followed to clean operative middle portion 262. As a result, the diameter of the z root canal in operative middle portion 262 has been widened, although, the original 1 perimetrical anatomy has not been substantially altered, partieuarly in the bottom half of f the operative middle portion 262 of root canal 252a.
A third instrument may also be added to each set of instrumentss which is an aggresive abrasion instrument having the same dimensions as the second iinstrument in each set. Each aggresive abrasion instrument may have an abrading ponrtion equally divided between an upper section covered with abrasive particles such as diiiamonds and a lower section that is twisted like the abrading portions of the other instruuments in the 10 sets. So for example, a third instrument in set 410 having a file with an uupper section configured for aggresive abrasion has an abrading portion that is 18 mm 1 long below a shank portion that is 2 mm long. The upper half of the shank portion is nobt twisted and is covered with diamonds while the lower half is twisted and has a length of f about 9 nnrn.
If the instruments are configured with a handle that enables them to y be used with 15 a handpiece configured for adjusting the working length of the instrtunent thaen the lengths of the file, the abrading portion and the shank portion are longer. More ~
particularly, instead of lengths of 16 mm,14 mm and 2 mm for the total file length, abra~ading portion length and shank portion length of the instruments described in Table 4A, tithe respective lengths are 19 mm, 16 mm and 3 mm. Similarly, the lengths of the instrumnents listed in 20 Table 4B as being 17 mrn, 15 rnm, 2 rnm for the total file length, abrading pportion length and shank portion length of the instruments are respectively 23 mm, 20 mnm and 3 mm when attached to a handle that enables the instrument to be used in a rnannner such that it can be moved within the chuck of the handpiece. Finally, the lengths of thae instruments listed in Table 4C as being 20 nun,18 mm, 2 mm for the total file length, abra-ading portion 25 length and shank portion length of the inshiunents are respectively 27 mm, ~ 24 mm and 3 mm when attached to a handle that enables the instrument to be used in a i manner such that it can be moved within the chuck of the handpiece.
Awical Portion Widening Phase and Related Sets o,~f Instru~ner~s A probe is then inserted to the apex of the root canal and another x,-ray image is 30 obtained. After the length has been determined the accessibility of the apidcal portion is assessed. If the apical portion is initially to small to permit entry of an irrigaation caimula then an optional set of instruments is selected for use in improving the acecess into the apical root portion or stated otherwise to enlarge the constricted region i between the w0 00!74589 PCTT/US00/08122 operative middle portion and the apical portion. This is achieved by manuall~ly moving one or more instruments until the transition zone between the operative middle portion and the apical root portion has been appropriately instrumented to have a diamneter of about .40 mm, which is suitable for accommodating the diameters of the smalltlest irrigation needles.
Again the practitioner has a comprehensive kit with several sets oi~f instruments which are designed for improving access into the apical root portion after the pulp material has been removed from the operative middle portion of a root canna!.
Each set is designed for use in a tooth with a different operative root canal length. r Accordingly, only one set from the kit is selected for use in operative root canal based on l the length of the particular anatomical root canal being treated.
Tables 5A, SB and SC detail the dimensions of instruments with file ldengths which are respectively 21 mm, 25 mm and 30 mm. In this example, the set presernted in Table 5B is selected. The set presented in Table SB is shown in Figure 35 as setst 440.
Table 5A/Apfcal Widening Instruments (21 mm) Inst.Total Abrad. SquareRound Tip Abrad SquareShank Taper No. LengthPortionPortionPortionDiam PortionPortion: Portion of Length LengthLength Diam, Diam. Diarn.
File (L, (Li) (La) (1.~3)(~i) (Da) (Da) (Da) +
Lz + L,) 1 21 5 mm 1 I 5 mm .08 .28 .30 .80 .04 mm mm mm mm mm mm 2 21 5 mm 11 5 mm .08 .38 .40 1,1 .06 mm mm mm mm mm mm Table SB/Apical Widening Instruments (25mm) Inst.Total Abrad.Square Round Tip Abrad SquareShank Taper No. LengthPortionPortionPortionpiam- PortionPortion1 Portion of LengthLength Lengtheter Diam. Diem. Diam.
Fiie (L~'H (Li) (Le) (L3) (~i) (D~) (D3) (Da) + L4) I 25 5 mm I S 5 mm .OS .28 .30 . .90 .04 mm mm mm mm mm mm 2 25 5 mm 15 mm 5 mm :08 .38 .40 '. 1.3 .06 mm mrrm mm mm mm WO 00/74589 PCT~'/FJS00/08122 Table SCIApical Widening Instruments (30 mm) Inst.Total Abrad.SquareRound Tip Abrad SquareShank Taper No. LengthPortionPortionPortionDiam- PortionPortionPortion of LengthLengthLengtheter Diam. Diam. Diam.
File ~L~'~'~Li) (La) CI-3) ~DO (Dx) (Da) (Da) Ls + L4) 1 30 5 mm 20 5 mm .08 :28 .30 1.1 .04 mm mm mm mm mm mm 2 30 S mm 20 5 rnm .08 .38 .40 1.6 .06 mm mm mm mm mm mm The files of the instruments in the sets detailed in Tables SA, SSB and SC are formed from stainless steel. Each file has three sections including a smooth ~
shank portion, a square portion and an abrading portion. As indicated above, the set pressented in Table 5B corresponds with set 440 shown in Figure 35. Note, however, with thQe exception of length, the instruments detailed in Table SA and Table SC would appear ju:ast like set 440.
Instrument 440a has a file 444a with smooth shank portion 446a, a squaree portion 447a, an abrading portion 449a and a file tip 448a. As shown, the smooth shanlak portion 446a is the top section of file 444a and a handle 442 is positioned on shank ;
portion 446a.
Smooth shank portion 446a tapers to square portion 447a which is betweenn shank portion 446a and abrading portion 449a.
The smooth shank portion enables stops be positioned on the fihle to adjust the working length of the file. Each smooth shank portion of each file has a ldength of about 5 mm with various diameters. The instruments can be used for all operati~ive lengths that are likely to be encountered in clinical practice through the positioning of tthe stops at the predetermined lengths. While the instruments can be offered in a more exxpanded series of millimetrically different lengths; the use of stops is acceptable, particulat3rly since, these instruments are manually moved.
In each set, the diameter at the top of the square portion of instrumnent number 1 and instrument number 2 is respectively .30 mm and .40 mm. The abradding portion is formed by twisting the square section so that the abrading portion n has a K-file configuration. The instruments in each set all have the same tip diameterss.
The taper of the files from the tip (D~) to the diameter at the top of the square portionn (D3) remains constant and is respectively .04 and .06 for instrument number 1 and instn~ument number 2 in each set.

WO 00!74589 PCTTIUS00l08122 Preferably, instrument 1 is first utilized and then instrument 2 t~to obtain;
in a gradual manner, the desired enlargement of the specific transition zoneie between the operative middle portion and the apical portion. This enlargement is alxlso preferably achieved without significantly changing the diameter of the apical portionn of the canal.
Accordingly, the tip diameter (D,) of the various instruments in this set remnains constant while the diameter at the top of the cutting area or abrading portion (D2), ;
located 5 mm from the tip, is graduated from one insrntment to the next, reaching a maxirirnum diameter of .38-mrn. The rest of the shaft, up to the handle, does not have a cuttinpg surface: To the extent that these instruments are used to expand the apical portion of f the canal, the practitioner should constantly bear in mind the average diameters of the c canals and the average thiclcnesses of the parietal walls at the apex, as listed in Table 2 a and Table 3.
After widening the apical portion of the root canal with the set shhown at 440 in Figure 35 and as detailed in Table SB, the root canal may appear as does rooot canal 252a in Figure 36C with a widened apical portion 264. More particuarly, the ~
region of root canal 252a extending from the bottom of operative middle portion 262 to t he top half of apical portion 264 has been noticeably widened. The bottom half of apical portion 264 has also been widened but to a much lesser degree.
.~~.nical Portion Cleaning Phase and Related Sets o,~f Instruments After the access into the apical portion has been adequately widened as discussed hereinabove and as shown in Figure 36C; the apical portion is cleaned.
Cleaning is halted at the working length as determined by the operator which should be at tthe apex. The practitioner should determine this length beforehand, based on the biological condition of the apico-periapical region, in terms -of the morphometrics of the ddiameters and thicknesses at the apex as set forth in the Table 2 and Table 3, and in accoradance with the amount of widening to be applied to the apical portion of the canal.
In this example, Example 2, a set of instruments is decribed for cleatming the apical portion in an abrasive manner after the portion of the root canal above the a apical portion has been cleaned. In Example 4, the preferred method of cleaning of the a apical portion through irrigation is used in combination with the instruments describedd above in this example for cleaning the portions above the apical portion.
Again sets of instruments are provided with each set having a dififferent length.
Three sets of instruments are described hereinbelow which are designed for r removing and cleaning essentially all pulp material from the apical root portion after aaccess into the W0 00/74589 PC'1;T/US00108122 apical root portion has been improved by a set of instruments such as set 4440 detailed in Table 5B. In some instances, the instruments described in this example caan also be used to clean the pulp material from the root canal immediately after the opoerative middle portion has been cleaned by a set of instruments such as the sets presenteed in Table 4C.
Tables 6A; 6B and 6C detail the dimensions of instruments with file:e lengths which are respectively 21 mm, 25 mm and 30 mm: However, please note that onnly instruments from Table 6B are used in the tooth being cleaned in this example. The set t of instruments detailed in Table 6B are shown in Figure 35 as set 470. Set 470 includdes instruments 470a-1 which respectively correspond with instruments 1-12 in the set presented in Table 6B.
The instruments in set 470 have a similar appearance as the instrumctents in set 440.
Instruments 470a-1 have a handle 472 opposite a file 474. Each file 4744 has a smooth shank portion 476x, a square portion 477, an abrading portion 479 and a filile tip 478. The sets of instruments presented in Table 6A and 6C have a similar appearance a to instruments 15. detailed in Table 6B and shown at 470, however, the files have differenht lengths: The taper of the files from the tip (D,} to the diameter at the top of the square I portion (D3) is provided in each table.
Table 6A/Apical Cleaning Instruments (25 mm) Inst.Total Abrad.SquareRound Tip Abrad Square Shank Taper No. Length PortionPottionPortionDiam- PortionPortionPortion of FileLengthLengthLengtheter Diam. Diam. Diam.
(I..i'F~(Li) (La) (La) (Dl) (Dz) (Ds) (Da) ~ L~) l 21 mm 5 mm I 1 5 mm .1 .20 .42 .50 0.02 mm O mm mm mm mm 2 21 mm 5 mm I 1 S mm ,15 .25 .47 .50 0.02 mm mm mm mm mm 3 2i mm 5 mm I1 5 mm .20 .30 .52 .60 0.02 mm mm mm mm mm 4 21 mm 5 mm l I 5 mm .25 .375mm.65 .70 0.025 mm mm mm mm .

5 21 mm 5 mm 1 I 5 mm .30 .425mm.70 .74 0.025 mm mm mm mm 6 21 mm 5 mm 11 5 rnm .35 .475mm.75mm .80 0.025 mm mm mm 7 21 mrn 5 mm 1 I 5 mm .40 .525mm.80mm .80 0.025 mm mm mm 8 21 mm 5 mm I I 5 mm .50 .625mm.90 .90 0.025 mm mm mm mm 9 21 mm 5 mm 1 I 5 mm .60 .725mm1.0 L0 0,025 mm mm mm mm 10 21 mm 5 mm I 1 S mm .70 .825mm1.1 1.1 0.025 mm mm mm mm WO 00/74589 PCT!'IUS00/08122 1 21 mm 5 mm 1 I 5 mm .80 .925mm1.2 1.2 0.025 I mm mm mm mm 12 21 mm 5 mm I 1 5 mm I .O 1.125 1.4 1.5 0.025 mm mm mm mm mm Table bBIApical Cleaning Instruments (25 mm}
5 Inst.Total Abrad.SquareRound Tip Abrad Square Shank Taper No. Length PortionPortionPortionDiam- PortionPortionPortion . LengthLengthLengtheter Diam. Diam. Diam.
of File~LO fLa) OL3) ADO ~Dx) CDs) ~De) ~L~
* ~
+ L<) I 25 mm 5 mm i5 5 mm .10 20 .50 .50 0.02 mm mm mm mm mm 2 25 mm 5 mm l5 S mm .15 :25 .55 .60 0.02 mm mm mm mm mm 3 25 mm 5 mm 15 5 mm .20 .30 ,60 .60 0.02 mm mm mm mm mm 10 4 25 mm 5 mm 15 5 mm .25 .375mm.75 .80 0.025 mm mm mm mm 5 2S mm 5 mm I3 5 mm :30 .425mm:80 .80 0.025 mm mm mm mm 6 25 mm 5 mm 15 5 mm .35 .475mm.85mm .90 0.025 mm mm mm 7 25 mm 5 mm 15 5 mm ,40 .525mm.90mm .90 0.025 mm mm mm 8 25 mm 5 mm 15 5 mm :50 .625mmI.0 1:0 0.025 mm mm mm mm 15 9 25 mm 5 mm 15 5 rtim.60 .725mm1.1 1.1 0.025 mm mm mm mm IO 25 mm 5 mm '15 5 mm .70 .825mm1.2 1.2 0.025 mm rnm mm mm I 25 mm 5 mm 15 Smm .80 .925mm1.3 1.3 0:025 l mm mm mm mm 12 25 mm 5 mm 15 5 mm 1.0 1:125 1.5 1.5 0.025 mm mm mm mm mm 20 Table 6C/Apical Cleaning Instruments (30 mm) Inst.Total Abrad.SquareRound Tip Abrad Square Shank Taper No. LengthPortionPortionPortionDiam- PortionPortionPortion ofFileLengthLengthLengtheter Diam, Diam. Diam.

~Lu+Ls~Li) (r~) ~La) ADO ~Dx) ~Da) Via) + L4) 1 30 5 mm 20 5 mm .10 .20 .60 :60 0.02 mm mm mm mm mm mm 2 30 5 mrn 20 5 mm .15 .25 .65 .70 0.02 mm mm mm mm mm mm 25 3 30 5 mm 20 5 mm ,20 .30 .70 .70 0.02 mm mm mm rnm mm mm WO 001?4589 PCTIffUS001081Z2 4 30 mm 5 mm 20 5 mm .25 .375mm.875mm.90 0.025 mm mm mm 5 30 mm S mm 20 5 mm .30 .425mm.925rnm1.0 0.025 mm mm mm 6 30 mm 5 mm 20 5 mm .35 .475mm.975mmL0 mm 0.025 mm mm 7 30 mm 5 mm 20 5 mm .40 .525mm1.025 1.1 0.025 mm mm mm mm S 8 30 mm 5 mm 20 5 mm '.50 .625mmI.125 1:2 0.025 mm mm mm mm 9 30 mm 5 mm 20 5 mm .60 .725mmI .225I.3 0.025 mm mm mm mrn 10 30 mm 5 mm 20 5 mm .70 :825mm1.325 1.4 U.025 mm mm mm mm 1 30 mm 5 mm 20 5 mm .80 .925mm1.425 1.5 0.025 I mm mm mm mm 12 30 mm 5 mm 20 5 mm 1.0 1.125 1.625 1.7 0.025 mm mm mm mm min After the apical portion has been properly widened; the practitionaer selects a set of files having the appropriate length, such as one of the sets presented in TTables fA, 6B
or 6C. To ensure that the files have an appropriate working length, it mayy be necessary to place stops around the shank portions of the files identified for example :', at 416a, 446a and 476a. The practitioner then selects an instrument from the set identifecid as having an appropriate length for introduction into the root canal down to the apical ~
portion.
As indicated above, in this example,. an instrument is selected from tithe set detailed in Table 6B, which is shown in Figure 35 as set 470. After selecting an innstrument; the practitioner then determines; based on feel and experience, whethaer the file is appropriately sized or whether a larger or smaller file is needed. For innstance, if the practitioner selects instrument number 2 from the set detailed in Table 6B Z
and shown in Figure 35 at 470b which has a tip diameter of .15 mm and the file. binds aafter insertion, then the practitioner would switch to instrument number 1 which has a titip diameter of .10 mm. Similarly; if instrument number 2 is too loose then the practitionoer would then switch to instrument number 3 which has a tip diameter of .20 mm. T'he praactitioner then uses that appropriately sized instrument to clean the apical portion of the a root canal by WO 00174589 PCTTfUS00/08122 hand. If the practitioner concludes after using an appropriately sized Tilde, that further instrumentation is still needed within the apical portion then the instrument~t with the next largest file may be used. It is typically unnecessary to use a third instrumentit with an even larger file after using a series of two instruments. However, the practitioner r may clean the apical root portion with a series of more than two instruments as deemed ne~ecessary by the practitioner in order to fully clean the apical portion.
After the apical portion of the root canal has been cleaned with thae set shown at 470 in Figure 35 and as detailed in Table 6B, the root canal may appear as ddoes root canal 2S2a shown in Figure 36D with a cleaned apical portion 264. More particuuarly, after use of an instrument such as instrument 2 from Table 6B shown at 470b, apicaal portion 264 may appear as shown. Note that cleaning apical portion 264 has substantialltly widened the bottom half of apical portion 264 while the top half is less significantl~ly flared when compared to its appearance before being cleaned. The appearance of apical portion 264 results from the different configurations of the respective abrading portions c of instruments used to widen and to clean the apical portion. More particularly, the diamneter of the tip (D,) and the diameter at the top of the abrading portion {D2) of the last instrument used to widen the apical portion, instrument 440b, are respectively .08 mm and .
.38 mm while instrument 470b has a tip diameter (D,) of .1 S mm and the diameter at t the top of the abrading portion (D2) is .25 mm. Stated otherwise, the :06 taper of abradingg portion 449b results in much greater flaring than the .02 taper of abrading portion 479b v~whiIe the large tip diameter of instrument 440b causes the widening of the lower half of a apical portion 264.
Set 410 and set 440 are preferably disposed after use. However, wince only one or two instruments from set 470 are used, it is preferable to replace ~ or clean the instruments used from set 470. All of the sets of instruments described inn this example may be sold together as a comprehensive kit or various sets may be groupaed together as kits intendEd for use with teeth of particular lengths. For example, the sects used in the tooth cleaned in this example which are detailed in Table 4C, SB and 6HB may be sold together. Additionally, since set 410 and set 440 are intended to be single a use sets these sets may also be sold together as a single use disposable kit.
Examnl~
This example describes another exemplary system for cleaning a raoot canal after the root canal has been properly accessed.

WO OOf74589 PCT~CJUS00/08122 Onexative Middle Portion nstrument:~
The sets of instruments designed for use in the operative middle ponrtion of a root canal are set in Tables 7A, 7B and 7C. In contrast to the sets of operative rrmiddle portion instruments described in Example 2, each of these sets include four instruixments instead of only two instruments. The lengths of the files in these sets include the vNarious lengths that are likely to be encountered in clinical practice which range predominnantely but not exclusively from 15 mm to 20 mm. Longer lengths, 25 mm, are typically nneeded for the middle segment of canine teeth. Accordingly, the files in each set of instrunments have the following'respective lengths: 17 mm, 20 mm and 25 mm. The lengths of tlihe instruments in these three sets encompass the average variations in length that arse likely to be encountered in clinical practice and in terms of the overall length of the opeerative coronal portion and the operative middle portion of various operative canals., Honwever, please note that other sets may also be useful as these three sets are merely ilhiustrative. For example, it may be useful to have a greater series of sets with lengths ranginpg from 15 mm 1 S to 20 mm in 1 mm increments and an additional set having a length of 255 rnm.
As in Example 2, one set of instruments is selected based on thee length of the tooth. Accordingly, after the length of the operative middle portion has beeen determined then either the set of instruments detailed in Table 7A, 7B or 7C is scelected and if necessary stops may be utilized to adjust the working length of the file.
WYhen the length of the operative middle portion has been appropriately determined, each onf these sets of instruments can be used to anatomically clean essentially all, pulp matt#erial from the operative middle portion of a root canal without significantly removing pulpy material from the apical root portion.
Table 7A/Operative Middle Portion Instruments (17 mm~) Instrument Total LengthAbrading Tip DiameterDiammeter at Number of the Portion (D,) top of the File Abrorading Portion (D2) 1 17 mm d 7 mm .10 mm .40 mm 2 i7 mm 17 mm .13 mm .50 mm 3 17 mm 17 mm .13 mm .70 mm 4 17 mm 17 mm .I3 mm :90 mm wo ooi7ass9 PcTrmsoo~osizz Table 7BfOperative Middle Portion Instruments (21 mm~) Instrument Total LengthAbrading Tip DiameterDia~ameter at number ofthe FilePortion (D,) top of the Abrasding Portion (Di) I 20 mm 20 mm .10 mm .45 mm 2 20 mm 20 mm .13 mm .55 mm 3 20 mm 20 mm .13 mm .75 mm 4 20 mm 20 mm .13 mm .95 mm Table 7C/Operative Middle Portion Instruments (25 mm~) Instrument Total LengthAbrading Tip DiameterDiaiameter at number of the Portion (D,) top of the File Abrerading Portion (D2) 1 25 mm 25 mm .1 D mm .55 mm 2 25 mm 25 mm : i 0 .65 mm mm 3 25 mm 25 mm .13 mm .75 mm 4 25 mm 25 mm .13 mm .95 mm The instruments in the sets detailed in Table 7A and Table 7B i include a first instrument with a tip diameter of about .10 mm while the other instrume.ents have a tip diameter of about .13 mm. The first and second instnunents in the set pressented in Table 7C have tip diameters of about .10 mm while the third and fourth instrunments have tip diameters of about .13 mm. It is oftenuseful to begin instrumenting with a sklightly smaller tip diameter, however, the difference in diameter is so small that these tip ~
diameters are considered to be essentially the same size: The difference is particularly insiggnificant when compared with the incremental increase in the size of the diameter tip frown instrument to instrument of conventional instruments used in conventional cleaning teachniques.
The sets of instruments described in this example would be expeccted to require more time to ,use than the instruments described in Example 2 as thhere are more instruments in each set. However, all of the sets can be used to clean the opperative middle portion without substantially changing the original anatomy of the rootnt canal. More particularly; each instrument is configured to enable a practitioner to movee the file along a side of the operative middle portion in a manner such that the originnal anatomy is enlarged without being modified to have just the shape of the instrument.t.

WO 0o17~t589 PCTT/US001081Z2 Note that the abrading portion of each file extends along the entire length of each file. Accordingly, each file is capable of simultaneously abrading botlth the operative coronal portion and the operative middle portion. In any event, the ahbrading portion extends beyond the conventional 16 mm length of instruments in presennt use.
Since sets are provided in different lengths it is not necessary to usse stops to adjust:
the ierrgth of the file as the handle of the instrument ensures that the innstrument stops safely at the proper working depth. Thus, the use of sets of instruments ~
with graduated lengths eliminates the problems associated with traditional stopping . depths.
More particularly; the sets reduce the amount of time required to position the ingstruments at the 10 desired length and eliminate the risk of bacterial contamination of the inst'truments due to handling:
A ical Pyr,~rn Wiafenin"~ I~trun~gnts The access into the apical portion is improved, if necessary, afteer the operative middle portion has been cleaned. More particularly, it is necessary to wuiden the access 15 into the apical root portion of the root canal in order to enable irrigants t'to be delivered as needed: The dimensions of a set of instruments which can be used for t this purpose are set forth in Table 5. The files of each instrument have a length of about~t 35 mm and an abrading portion which is about 5 mrn long.
20 Table 8/Apical Widening Instruments (35 mm) InstrumentTotal Abrading Tip DiameterDiameter:r Taper Number Length Portion (D,) he top ofthe Length of the Ahbrading File (L~ ) Portiornn (L, + (D=) L3 +
L,) 1 35 mm 5 mm .08 mm .20 mnm .020 2 35 mm 5 mm :08 mm .25 rrtrim .020 25 3 35 mm 5 mm .08 mm .34 rrmm .036 4 35 mm 5 1i1 .08 mm .35 rrmm .045 The instnunents would each be expected to be useful for improvingg access into the apical root portion after the pulp material has been removed from the opperative middle 30 portion of a root canal. However, such a set of instruments would be expoected to require more time to use than one of the sets of instruments described in Examplale 2 as there are more instruments in this set.

?6 A~~ical Portiarn Cleaning Instruments After the access into the apical portion has been adequately widenned, the apical portion is cleaned. One of the sets of instruments detailed in Tables bA, f 6B
or 6C may be used to clean the apical portion or alternatively the set detailed in Table 99 may beused.
Each instrument in the set described in Table 9 has a file with a working leength of about 35 mm and an abrading portion which is about 5 mm long. The files of thhe instruments all have the same tip diameters and have increasing larger tapers.
Table 9 InstrumentTotal LengthAbrading Tip Diameter at Taper Number of Portion Diameterthe C top of the File Length (D~) the Abrading (L~ + Lj W ) Po'ortion + L4) (Dz) 1 35 mm 5 mm .06 .18 mm .02 mm 2 35 mm 5 mm .08 .20 mm .02 mm 3 35 mm S mm .10 .22 mm .02 mm 4 35 mm S mm .15 .27 mm .02 mm 5 35 mm 5 mm .20 .32 mm .02 mm 6 35 mm 5 mm .25 .37 mm .OZ
mm 7 35 mm S mm .30 .42 mm .02 mm 8 3S mm 5 mm .35 .47 mm .02 mm ' 9 I 35 mm ~ S mm :40 .52 mm .02 mm The set of instruments detailed in Table 9 have longer files than thee sets provided in Tables 6A, 6B and 6C so more stops would be necessary. In most othaer respects the set in Table 9 is very similar to the other sets discussed in Example 2 foDr cleaning the apical portion. Note, however, that the set in Table 9 begins with smaller:r tip diameters which may be useful in same instances.
Example 4 This example describes an exemplary system for cleaning a root c canal without abrasively cleaning the apical portion. The apical portion is cleaned after:r the operative puddle portion has been cleaned with set 410 as set forth in Example 2. Access into the apical portion may also have been improved through the use of set 440 aas described in Example 2. Cleaning of the apical portion is then initiated by insertiring a cleaning WO 00!74589 PCT/f/US00/08122 instrument into the apical portion as shown in Figure 20A and Figure 20B annd deliverying irrigants. The cleaning instrument is a cannula 760 of an endodontic irrigatttor tip 720, as previously; described in reference to Figure 20A and Figure 20B. After syr,~ringe 790 has been used to deliver irrigants into root canal 782, the irrigants and any rernnaining debris may be removed by any suitable method such as aspiration using irrigator tilip 720 coupled to an aspirator device so that the tooth appears as shown in Figure 20B at t 780.
Note in addition to set 410 and set 440 being disposable after use, irnrigator tip 720 is also preferably disposable. Note also that instead of a large set of instrunments like set 470, only a single irrigator tip need be used so it is much less expensive to mnerely irrigate.
I O It is also less time intensive since it is not necessary to use a series of apicalii instruments.
All of the instruments described in this example rnay be sold individually c or together as a comprehensive kit.
The present invention may be embodied in other specific forms withhout departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrated and not restrictive, The scope off the invention is, therefore, indicated by the appended claims rather than by the foregoinpg description.
All changes which come within the meaning and range of equivalency of thae claims are to be embraced within their scope.
What is claimed is:

Claims (32)

1. An endodontic instrument system adapted for anatomical cleaning of the operative coronal portion, the operative middle portion and the apical root portion of an operative root canal in a tooth, the endodontic instrument system comprising:
first endodontic instrument configured for use in the operative middle portion of an operative root canal to anatomically clean essentially all pulp material from the operative middle portion, the first endodontic instrument including a file having a top end opposite a tip, the file having a length corresponding to at least the combined length of the operative coronal portion and the operative middle portion in order to remove pulp material from essentially all of the operative middle portion of the operative root canal, the file having an abrading portion for removing pulp material, the file being able to flex such that the abrading portion is urged against root canal surfaces while the file is rotated and moved in a cleaning motion, thereby enabling contours of the operative middle portion to be used as a guide for movement of the file in conformance to the anatomical shape of the operative middle portion while effecting removal and cleaning of pulp material from essentially all of the operative middle portion, and a handle connected to the top end of the file, the handle being configured to enable a user to operatively move the file in an abrasive action while bending and flexing the file within the operative middle portion of the operative root canal;
and an apical portion cleaning instrument adapted for cleaning the apical root portion through the delivery of an irrigant after the pulp material has been essentially removed from the operative coronal portion and the operative middle portion by the first endodontic instrument.

2. An endodontic instrument system as defined in claim 1, wherein the file of the first endodontic instrument has sufficient rigidity to apply pressure against the root canal surfaces via the abrading portion as the file is flexed to urge the abrading portion against root canal surfaces and as the file is simultaneously moved in a cleaning motion.

3. An endodontic instrument system as defined in claim 1, wherein the file of the first endodontic instrument is configured to enable a practitioner to move the file around the perimeter of the operative middle portion of the operative root canal.

4. An endodontic instrument system as defined in claim 1, wherein the file of the first endodontic instrument is configured to enable a practitioner to move the file along a side of the operative middle portion in a manner such that the tip does not remain primarily in one position as the operative middle portion is cleaned.

5. An endodontic instrument system as defined in claim 1, further comprising a stop configured to be positioned on the file of the first endodontic instrument in order to limit insertion of the file into the operative coronal portion and the operative middle portion without substantially extending into the apical portion.

6. An endodontic instrument system as defined in claim 1, wherein the file of the first endodontic instrument has a shank portion above the abrading portion and below the handle, wherein the shank portion is adapted to receive a stop.

7. An endodontic instrument system as defined in claim 1, wherein the file of the first endodontic instrument has a length that limits the penetration of the file in the root canal to essentially only the operative middle portion of the root canal.

8. An endodontic instrument system as defined in claim 1, further comprising a second endodontic instrument configured to adequately improve access into the apical root portion after the pulp material has been essentially removed from the operative middle portion by the first endodontic instrument such that irrigants can be delivered into the apical portion of the root canal from an irrigation needle.

9. An endodontic instrument system as defined in claim 1, further comprising a second endodontic instrument configured for improving access into the apical root portion after the pulp material has been essentially removed from the operative middle portion by the first endodontic instrument, wherein the second endodontic instrument includes:
a file having a top end opposite a tip, the file having a length that enables the file to reach within the apical portion of the root canal, the file having an abrading means for removing pulp material, the abrading means being located on a portion of the file such the abrading means can be moved against the root canal to improve the access into the apical portion of the root canal; and a handle connected to the top end of the file of the second endodontic instrument.

10. An endodontic instrument system as defined in claim 1, wherein the apical portion cleaning instrument is an irrigator tip adapted for coupling with a delivery device to deliver an irrigant into the apical portion after the pulp material has been essentially removed from the operative middle portion.

11. An endodontic instrument system as defined in claim 1, wherein the apical portion cleaning instrument is an irrigator tip coupled to a delivery device to deliver an irrigant into the apical portion after the pulp material has been essentially removed from the operative middle portion.

12. An endodontic instrument system adapted for anatomical cleaning of the operative coronal portion, the operative middle portion and the apical root portion of an operative root canal in a tooth, the endodontic instrument system comprising:
a first endodontic instrument configured for use in the operative middle portion of an operative root canal to anatomically clean essentially all pulp material from the operative middle portion, the first endodontic instrument including a file having a top end opposite a tip, said file having a length corresponding to at least the combined length of the operative coronal portion and the operative middle portion in order to remove pulp material from essentially all of the operative middle portion of the operative root canal, the file having an abrading portion for removing pulp material, the file being able to flex such that the abrading portion is urged against root canal surfaces while the file is rotated and moved in a cleaning motion, thereby enabling contours of the operative middle portion to be used as a guide for movement of the file in conformance to the anatomical shape of the operative middle portion while effecting removal and cleaning of pulp material from essentially all of the operative middle portion, and a handle connected to the top end of the file, the handle being configured to enable a user to operatively move the file in an abrasive action while bending and flexing the file within the operative middle portion of the operative root canal;

a second endodontic instrument configured for improving access into the apical root portion after the pulp material has been essentially removed from the operative middle portion by the first endodontic instrument; and an apical portion cleaning instrument adapted for cleaning the apical root portion after the pulp material has been essentially removed from the operative coronal portion and the operative middle portion.

13. An endodontic instrument system as defined in claim 12, wherein the file of the first endodontic instrument has sufficient rigidity to apply pressure against the root canal surfaces via the abrading portion as the file is flexed to urge the abrading portion against root canal surfaces and as the file is simultaneously moved in a cleaning motion.

14. An endodontic instrument system as defined in claim 12, wherein the file of the first endodontic instrument is configured to enable a practitioner to move the file around the perimeter of the operative middle portion of the operative root canal.

15. An endodontic instrument system as defined in claim 12, wherein the file of the first endodontic instrument is configured to enable a practitioner to move the file along a side of the operative middle portion in a manner such that the tip does not remain primarily in one position as the operative middle portion is cleaned.

16. An endodontic instrument system as defined in claim 12, further comprising a stop configured to be positioned on the file of the first endodontic instrument in order to limit insertion of the file into the operative coronal portion and the operative middle portion without substantially extending into the apical portion.

17. An endodontic instrument system as defined in claim 12, wherein the file of the first endodontic instrument has a shank portion above the abrading portion and below the handle, wherein the shank portion is adapted to receive a stop.

18. An endodontic instrument system as defined in claim 12, wherein the file of the first endodontic instrument has a length that limits the penetration of the file in the root canal to essentially only the operative middle portion of the root canal.

19. An endodontic instrument system as defined in claim 12, wherein the second endodontic instrument comprises a file having a top end opposite a tip, the file having a length that enables the file to reach within the apical portion of the root canal, the file having an abrading portion for removing pulp material, the abrading portion being located on the file such the abrading portion can be moved against the root canal to improve the access into the apical portion of the root canal, and a handle connected to the top end of the file of the second endodontic instrument.

20. An endodontic instrument system as defined in claim 12, wherein the second endodontic instrument is configured to adequately improve access into the apical root portion after the pulp material has been essentially removed from the operative middle portion such that irrigants can be delivered into the apical portion of the operative root canal from an irrigation needle.

21. An endodontic instrument system as defined in claim 12, wherein the apical portion cleaning instrument comprises an irrigator tip adapted for coupling with a delivery device to deliver an irrigant into the apical root portion after the pulp material has been essentially removed from the operative middle portion.

22. An endodontic instrument system as defined in claim 12, wherein the apical portion cleaning instrument comprises an irrigator tip and wherein the irrigation tip is coupled to a delivery device to deliver an irrigant into the apical root portion after the pulp material has been essentially removed from the operative middle portion .

23. An endodontic instrument system as defined in claim 12, wherein the apical portion cleaning instrument comprises a file with a top end extending from a handle, wherein the file has a tip opposite the top end, wherein the file has an abrading portion for removing pulp material, the abrading portion being located on the file such that the abrading portion can remove the pulp material from the apical portion of the root canal.

24. An endodontic instrument adapted for mechanical rotation to anatomically clean the operative coronal portion and the operative middle portion of an operative root canal in a tooth, the endodontic instrument comprising:
a file having a top end opposite a tip, said file having a length corresponding to at least the combined length of the operative coronal portion and the operative middle portion, said file having an abrading portion with abrasive particles on at least an upper section of the file for aggresive abrasion and with a lower section below the upper section that is less abrasive than the upper section, said file being able to flex such that the abrading portion is urged against root canal surfaces while the file is rotated and moved in a cleaning motion, thereby enabling contours of the operative middle portion to be used as a guide for movement of the file in conformance to the anatomical shape of the operative middle portion while effecting removal and cleaning of pulp material from essentially all of the operative middle portion, and a handle connected to the top end of the file, the handle being configured to enable a user to operatively move the file in an abrasive action while bending and flexing the file within the operative middle portion of the root canal.

25. An endodontic instrument as defined in claim 24, wherein said lower section of the file that is twisted to have a fluted configuration.

26. An endodontic instrument as defined in claim 24, wherein the upper section has a length that is no greater than about half of the length of the file.

27. An endodontic instrument as defined in claim 24, wherein the upper section has a length that is in a range from about 4 to about 10 mm in length.

28. An endodontic instrument as defined in claim 24, wherein the abrasive particles are diamond particles.

29. An endodontic instrument as defined in claim 24, wherein the abrasive particles are selected from the group consisting of refractories of silicon carbide and fused alumina, aluminum oxide, natural aluminum oxide, alumina ceramics, glass, silicon dioxide, silicon carbide, boron nitride, and other comparably hard materials.

30. An endodontic instrument as defined in claim 24, wherein the abrasive particles have an average particle size in a range from about 30 µm to about 350 µm.

31. An endodontic instrument as defined in claim 24, wherein the abrasive particles are positioned on the upper section of the file with a thickness in a range from about 100 µm to about 700 µm.

32. An endodontic instrument as defined in claim 24, wherein said file has a shank portion above the abrading portion.