WO2010021535A2

WO2010021535A2 - Retrievable dental prosthesis attachment device and tools thereof

Info

Publication number: WO2010021535A2
Application number: PCT/MY2009/000119
Authority: WO
Inventors: Kai Foo Chow
Original assignee: Kai Foo Chow
Priority date: 2008-08-18
Filing date: 2009-08-18
Publication date: 2010-02-25
Also published as: MY155027A; WO2010021535A3

Abstract

Method and devices to enable easy and economical installation and maintenance of retrievable dental prostheses mounted onto O-ball head mini dental implants. The devices disclosed are a dental prosthesis attachment device (17), an O-ring insertion/removal tool (25) and a paralleling drill guide (33). The familiar O-ring-in-housing denture stabilization device (55) is now amenable to retrievably attach crowns and bridges to O-ball head mini dental implants (10) by extending the base of said denture stabilization device (55) to engage snugly over the cylindrical collar (14) of a O-ball head mini dental implant (10) when used in conjunction with the disclosed O-ring insertion/removal tool (25) and paralleling drill guide (33).

Description

RETRIEVABLE DENTAL PROSTHESIS ATTACHMENT DEVICE AND TOOLS THEREOF

BACKGROUND OF THE INVENTION:

1. Technical Field of the Invention

This invention relates to dental implant supported prostheses in general and, in particular, to a method and devices for mounting retrievable dental prostheses onto O-ball head mini dental implants.

2. Description of the Prior Art

Dental prostheses like crowns and bridges have been in use for a long time. Previously, crowns and bridges were cemented to shaved down abutment teeth or onto posts inserted into tooth roots. The crowns are fixed to the abutment teeth or posts with permanent cement. This will incur a tooth root-cement-crown junction. Excess cement is readily removed.

With the advent of dental implants, the use of natural healthy teeth or healthy tooth roots for supporting dental prostheses is declining. Increasingly, dental prostheses are being supported by dental implants placed into jaw bone. The portion of the implant that is submerged in bone is equivalent to the tooth root. This tooth root equivalent is smaller than a natural tooth root. As a result, a crown fixed to a dental implant -abutment using permanent dental cement will incur a gum-cement-crown junction. Excess cement lies in the crevice between gum and crown and is not readily removable. This junction has been described as an "endotoxin trap". Moreover permanent cementation renders the thus fixed crown extremely difficult to retrieve for hygiene or treatment purposes.

O-ball head mini dental implants and its use for stabilization of dentures has been a ^' boon to patients since its teaching in U.S. Pat. No. 6716030 by Sendax et al. The use of this system enables minimally invasive surgery M lower cost to patient. Stabilization of dentures through the use of O-ball head mini dental implants attached to dentures via O- ring-in-housing has become well known in. the art. In this system, a metal housing housing an O-ring is embedded in the denture base and couples with the O-ball head mini dental implant that has been embedded in the jaw bone. The metal housing with its O-ring just snaps over the O-ball head of such mini implants and there is considerable mobility such that this mechanism is only suitable for use with dentures which have a big and stable base. For the mounting of well fitting crowns and bridges that do not have such big bases this system is not suitable as there is too much mobility and it would be unstable. Use of mini 'dental implants for mounting crowns and bridges employ means of permanent dental cement as has been set out above, with the attendant limitations.

U.S. Pat No. 7033174 granted to Giorno teaches a prosthesis mounting device for use with such implants. As the O-ball head abutment that protrudes beyond the gum line is small and Ml of undercuts it is not suitable for direct impression taking. A coping and such like devices used together with lab analogues through indirect impression techniques would be needed to fabricate a well fitting crown. This would be more costly and tedious to both dentist and lab compared to a direct impression technique. U.S. Pat. No. 7108511 granted to Shatkins teaches a technique to enable a prefabricated prosthesis to be fitted onto mini dental implants as a single stage procedure.

These techniques have enabled successful mounting of crowns to mini dental implants. However, due to their small size, the gum-cement-crown junction is sizable and cleaning up excess cement after cementation is tedious and difficult. And permanent cementation renders the thus fixed crown practically irretrievable for hygiene or treatment purposes.

To enable smooth insertion of crowns and bridges over them, implants have to be placed as parallel as possible. This is very difficult to achieve by visual judgement alone. U.S. Pat. No. 6626667 granted to Sussman discloses a drill guide suited to an edentulous jaw and U.S. Pat No. 7153132 granted to Tedesco requires a base plate to be seated immovably between teeth. And U.S. 7108511 granted to Shatkins teaches a lab fabricated surgical stent to be fitted over existent teeth. In these various drill guides the various means to secure and immobilize the drill guide can be improved upon.

There exists in the field a need for an elegant technique to enable readily retrievable implant supported prostheses. And should cement fixed prostheses be preferred, ready removal of excess cement, and ease of cleaningf is still possible. And where O-ball head mini implants are used, the size and shape of the abutment should be augmented and modified such that direct impression taking is possible. There is also a need to add on to existing drill guides so that the job of placing implants parallel to each other is made easier. SUMMARY OF THE INVENTION

The present invention discloses a dental prosthesis attachment device, an O-ring 'insertion/removal tool for use with the dental prosthesis attachment device and the use of the dental prosthesis attachment of this invention in a paralleling drill guide.

It is an object of this invention to enable dental prostheses to be mounted onto O- ball head mini dental implants without the use of permanent cement which would incur an undesirable gum-cement-crown junction¹ and renders so attached prostheses virtually irretrievable for treatment or hygiene purposes. It is an object of this invention to enable prostheses mounted onto O-ball head mini dental implants to be retrievable. It is a further object of this invention to promote a healthy gum-crown, gum-implant junction. This object is also achieved even when cement fixation is chosen over the retrievable O-ring attachment function.

Yet another object of this invention is to make the process of mounting crowns and bridges onto O-ball head mini dental implants easier and cheaper.

The forgoing objects are met by the disclosure of the dental prosthesis attachment device and paralleling drill guide. To obviate the need to use permanent cement to mount dental prostheses straight onto O-ball head mini dental implants, the dental prosthesis attachment device is used instead. This dental prosthesis attachment device uses a coupling mechanism well known in the art i.e. an O-ring to grip the neck of an O-ball head mini dental implant. Prior art could only apply this coupling mechanism to secure dentures as the housing of the O-ring extends only over the O-ball head of the mini dental implant. There would be too much mobility and instability if used for securing crowns and bridges which do not have big stable bases. However, by extending the base of the housing so that it extends at least partway onto the collar of an O-ball head mini dental implant as well as fitting snugly around this cylindrical collar, sufficient rigidity and stability is achieved. Thence, even crowns and bridges can be secured. And when the O-ball head mini dental implant is positioned such that when a dental prosthesis attachment device is placed on it, the dental prosthesis attachment device would somewhat impinge the gum, a healthy gum- crown interface results. The dental prosthesis attachment device has a frusto-conical shape and when placed over an O-ball head mini dental implant enables direct impression taking. There is no need for copings and lab analogues, making the process easier and cheaper for both dentist and lab. And, for mounted prostheses to be retrievable, placing parallel implants is essential. With the use of the disclosed paralleling drill guide, which also employs means of the dental prosthesis attachment device, the placing of parallel implants is quite easily achieved.

A further object is to make the maintenance of such retrievable prostheses easy and economical. This object is met with the disclosure of the O-ring insertion/removal tool.

As the O-ring is placed deeply into a tiny narrow recess, the use of this tool enables a worn O-ring to be easily replaced by patient or dentist. Further, the O-ring being used in this invention is preferably an elastomeric orthodontic ligature size 120 which is cheap and easily available to any dentist. Any standard elastomeric orthodontic ligature may be applicable or even any material and size of O-ring with the provision that the dimensions of the dental prosthesis attachment device shall be adjusted accordingly.

As set forth above, the use of this prosthesis attachment device will still achieve the object of enabling ease of removal of excess cement and easy access for cleaning by patient when cement fixation is preferred over detachable O-ring fixation. When cement fixation of the prosthesis attachment device is done, excess cement is readily removed. The next step is to slip a rubber dam with a central punched out hole of around 2.5mm diameter over the cemented prosthesis attachment device to grip the mini implant. Direct impression technique is again used over the rubber dam. Thence the impression of the whole prosthesis attachment device is picked up and a so fabricated crown is amenable to flossing all the way to the gum-implant junction.

Elegantly, the perennial problem of excess cement and poor access for cleaning in implant supported prostheses is solved. Firstly, employing a, detachable O-ring fixation allows retrievability and obviates the need for dental cement. And secondly, when cement fixation is used, the step of slipping a rubber dam over the prosthesis attachment device before direct impression taking enables a prosthesis underside that allows flossing all the way to the gum-implant junction, thus ensuring easy accessibility for cleaning purposes.

The present invention affords many advantages not found in prior art and will enhance the applications of O-ball head minis dental implants. When taken with the description of the following drawings the various features and advantages will become apparent.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig Ia is a perspective view of the upper part of an O-ball head mini dental implant. Fig Ib is a plan view of an O-ball head mini dental implant. Fig Ic is a vertical cross sectional view of the O-ball head abutment of Fig Ia.

Fig 2a is a top view of the O-ring.

Fig 2b is a cross sectional view of the O-ring.

Fig 3 is a vertical cross sectional view of a crown secured to two O-ball head mini dental implants with permanent dental cement as in prior art.

Fig 4 is a vertical cross sectional view showing an O-ring-in housing denture attachment device used for denture stabilization.

Fig 5a is a vertical cross sectional view of one embodiment of the prosthesis mounting device.

Fig 5b is a vertical cross sectional view of various embodiments of the prosthesis mounting device shown in long dotted lines with the O-ball head abutment shown in short dotted line.

Fig 6a is a schematic view illustrating the O-ring insertion process.

Fig 6b is a side view of the O-ring insertion/removal tool.

Fig 7a is a vertical cross sectional view of the paralleling drill guide.

Fig 7b is a top view of the paralleling drill guide.

Fig 8 is a schematic view illustrating the dental prosthesis attachment device in use.

Fig. 9a is a buccal view of the dental prosthesis attachment device seated on a ridge of a patient that is flat and at an incline.

Fig. 9b is a buccal view of the dental prosthesis attachment device seated on a ridge of a patient that is curved and substantially level. .

Fig. 9c is the buccal view of the dental prosthesis attachment device seated on a ridge of a patient that is curved and at an incline.

DETAILED DESCRIPTION OF THE DRAWINGS

Figs Ia, Ib and Ic show various views of the upper part of an O-ball head mini dental implant (10). The threaded shaft (15 Fig Ia) tapers to a point (not shown) as in a self tapping screw and is inserted into a prepared hole in the jaw bone. Beyond this threaded shaft (15) is the O-ball head abutment (45) which is shown in cross section in Fig Ic. This abutment end will protrude out of the jaw bone and gum. Most distally to the threaded shaft (15) end is the O-ball head (11) of diameter 1.7mm. This O-ball head (11) sits on a cylindrical neck (12) that is slightly narrower at 1.3mm diameter and is of height 0.8mm. The cylindrical neck (12) sits on a square shoulder (13) of sides 1.7mm and height 1.5mm. This square shoulder (13) sits on a cylindrical collar (14) of diameter up to 2.5mm. Thus the O-ball head abutment (45) consists of an O-ball head (11) seated on a slightly 'narrower cylindrical neck (12) that sits on a slightly bigger square shoulder (13) which sits on a slightly bigger cylindrical collar (14) (Fig Ib). For the purpose of this invention, an O- ball head mini dental implant includes all mini dental implants with a head and a neck wherein the head can be spherical, elliptical, semi-spherical with a flat top and the like, and the cylindrical collar (14) may vary such that the sides may also be tapered.

Fig 2a shows a plan view of an O-ring (16) used in this invention. Fig 2b is the vertical cross-sectional view. The outer diameter OD is 3.Omm and the inner diameter ID is 1.3mm (Fig 2a) and the cross sectional height H is 0.8mm (Fig 2b). These dimensions are met in the cheap and readily available elastonieric orthodontic ligature size 120. The above describes the dimensions of the most commonly used O-ball head mini dental implant. The dimensions of the O-ball head mini dental implant may deviate from that described above, depending on the application requirement. Accordingly, depending on the dimensions of the O-ball head mini dental implant (10), other O-ring sizing between elastomeric orthodontic ligatures size 90 and 130 are also possible. Other materials suitable for dental application may also be used. Such material may also be metal such as stainless steel or titanium whence the "O-ring" will be a "C-shaped" ring to enable the grip and release function of an elastomeric O-ring.

Fig 3 is a vertical cross-sectional view of two O-ball head mini dental implants (10) embedded into jaw bone (not shown) through gum tissue (40) with a crown (56) directly cemented onto the O-ball head mini dental implant (10) with dental cement (57), excess of which flows out to form a gum-cement-crown junction (58) as excess cement is hard to remove. This illustrates the prior art.

Fig 4 is a vertical cross sectional view showing a prior art of a denture attachment device (55) which consists of a housing (7') housing an O-ring (16') engaging O-ball head abutment (45) at its cylindrical neck (12). This/ denture attachment device (55) extends only over the head and neck of the O-ball head abutment (45) and therefore there is much associated mobility. The O-ring (16') is_^ in a shallow location and does not need any specialized tool for removal or insertion. The O-ring (16') usually employed is not readily available and replacement of worn O-rings is costly and inconvenient.

Now this just described denture attachment device (55) can act as a crown and bridge attachment device if it can be made more rigid and stable. In the present invention this rigidity and stability is achieved by extending the housing (7') to cover at least part of the cylindrical collar (14) of the O-ball head abutment (45) as well to fit snugly around this "cylindrical collar (14). This now renders the O-ring (16') not easily assessible and replacement of worn O-rings would require a specialized tool. Such a specialized O-ring insertion/removal tool (25), described in Figs 6a and 6b, is necessarily disclosed in order to carry out the present invention. Instead of the usual O-ring (16') which is costly and not readily available, the preferred O-ring used in this invention, as described earlier, is the elastomeric orthodontic ligature size 120.

Figs 5a and 5b show the dental prosthesis attachment device (17) of this invention. The dental prosthesis attachment device (17) has a frusto-conical shaped housing (7) with a broader circular base (21) tapering evenly to a smaller diametered circular apical end. That is the external contours of the dental prosthesis attachment device (17) resemble a cone with the apex cut off. The frusto-conical shaped housing (7) has a peripheral wall (19) encompassing a cylindrical recess (20). The cylindrical recess (20) extends axially from the circular base (21) and ends at a roof (9) formed by the capping (23) at the apical end of the dental prosthesis attachment device (17). The cylindrical recess (20) extends from the base (21) for an inner height D plus B. The O-ball head abutment (45) is shown in short dotted lines. D is the height of the cylindrical neck (12) and O-ball head (11). B is the basal height measured from the square shoulder to lmm onto the cylindrical collar (refer Fig Ic). The diameter of the cylindrical recess (20) is sized to enable cooperative -mating between the cylindrical recess (20) of the dental prosthesis attachment device (17) and the cylindrical collar (14) of the O-ball head mini dental implant (10). Should the cylindrical collar (14) be some what tapered the dimensions of the cylindrical recess (20) can be adapted to accommodate the final profile of the cylindrical collar (14). An annular groove (18) is positioned horizontally at a height to engage the neck of the implant abutment (45) i.e. just above the square shoulder (13). This annular groove (18) is cut into the peripheral wall (19) of the dental prosthesis attachment device (17) such that it is just big enough to seat the O-ring (16). In use, the dental prosthesis attachment device (17) with O-ring (16) in place will snap over the O-ball head of implant abutment (45) and engage the cylindrical neck (12) of the O-ball head abutment (45). On pulling, the dental prosthesis attachment device (17) will snap off the implant abutment (45). A dental prosthesis fixed onto dental prosthesis attachment device (17) with dental cement becomes easily retrievable for hygiene or treatment purposes. The profile of the ridge (50) of any patient, in practice, is usually undulating and may be flat, curved, inclined or a combination. In order to achieve good prosthesis-gum interface and maintain vertical alignment, the profile of the base (21) should conform to the profile of the ridge of the respective patient. Accordingly, although the dental prosthesis attachment device (17) is illustrated with a base (21) that is circular, it is obvious to someone skilled in the art that the base (21) may also be prefabricated to cater to patients with gum surfaces that may be flat, curved, inclined or a combination of such profiles.

Fig. 9a shows an example of a ridge (50) of a patient having gum surface that is substantially flat but inclined. In this case, the base (21) of the dental prosthesis attachment device (17) can be adapted to be of elliptical shape such that the housing (7) dental prosthesis attachment device (17) becomes oblique fhisto-conical shaped, with the lengths of the peripheral wall (19) varying from the longest lateral length at one antipodal point of the transverse diameter of the ellipse to the shortest lateral length on the other antipodal point of the transverse diameter.

Fig. 9b shows an example of. a ridge (50) of a patient having gum surface that is curved and substantially level. In this case, the base (21) of the dental prosthesis attachment device (17) can be adapted to have two oppositely positioned arcs (51), making up part of the perimetrical edges of the base (21), with the end points of each arc (51) starting from the base (21). The length and curvature of the arcs (51) are substantially the same. The dental prosthesis attachment device (17) is only symmetrical about a plane between the arcs (51) and is not rotationally symmetrical as with a dental prosthesis attachment device (17) having a flat circular base (21). In this example, the arcs (51) at the base (21) of the dental prosthesis attachment device (17) sit cireumferentially on the ridge (50) of the patient.

Fig. 9c shows an example of a ridge (50) of a patient having gum surface that is curved and at an incline. In this case, the base (21) of the dental prosthesis attachment device (17) can be adapted to have two oppositely positioned arcs (51', 51") making up part of the perimetrical edges of the base (21), with the end points of each arc (51', 51") starting from the base (21) but with the length and curvature of one arc (51") longer and larger respectively than the opposing arc(51'). In use, the arcs (51', 51") of the dental prosthesis attachment device (17) sit cireumferentially on the ridge (50) of the patient, with the arc (51") of larger curvature sitting on the higher end of the inclined ridge (50). Referring to Fig 5b, the dental prosthesis attachment device (17) has an outer height B plus D plus A. A is the apical height of the capping (23) of the dental prosthesis 'attachment device (17). Different dimensions can be designed such that the base diameter and outer height vary. As shown in long dotted lines, the dental prosthesis attachment device (17', 17") may have apical height A' that is much shorter than apical height A and basal heights B' or B" that is longer than B and engages more of the cylindrical collar whilst ensuring the annular groove (18) is located correctly to be at the position of the neck of the implant abutment (45). This would give the clinician choice to place just the right sized device for optimal prosthesis seating taking into consideration loss of bone height, occlusal relationships etc. Various surface features enhance the practical usefulness of the dental prosthesis attachment device (17). (22) indicates the edges that are rounded. Small external grooves (24) enhance cement retention of mounted prostheses. Suitable materials for the housing (7) would be surgical grade stainless steel, titanium or a high performance plastic, whence the O-ring could be integral with the rest of the housing.

The annular groove (18) that seats the O-ring (16) is located rather deeply into the cylindrical recess (20) of the dental prosthesis attachment device (17). An O-ring insertion/removal tool (25) is necessarily disclosed for the practice of this invention. This O-ring insertion/removal tool (25) is also essential when time comes for the replacement of worn O-rings. Fig 6b shows a side view of this tool. A central longish handle (28) has an O-ring removal tool (26) at one end. This is a pin with a hook at its end (46), just sized to fit into the cylindrical recess (20) of the dental prosthesis attachment device (17). On applying the hook (46) into the cylindrical recess (20) beyond the location of the O-ring (16), the O-ring (16) is easily hooked out. At the opposite end is attached the O-ring insertion tool (27). This comprises a ball head pin (29) with a slidable sleeve (31) located just distal to the ball head (30). This sleeve is a hollow tube just big enough to fit into the cylindrical recess (20) of the dental prosthesis attachment device (17). In use, (refer Fig 6a) the ball head (30) of the O-ring insertion tool (27) picks up an O-ring (16) to transfer into the cylindrical recess (20) of the dental prosthesis attachment device (17). The O-ring (16) is placed in a downward direction at an angle into the cylindrical recess (20). Thus positioned, the slidable sleeve (31) is pushed downward toward the annular groove (18), seating the O-ring (16) into the annular groove (18).

This invention would not be complete without the disclosure of a paralleling drill guide (33). Placing implants parallel to each other is often important in constructing successful prostheses. And to ensure retrievability of prostheses, placing parallel implants is essential. Referring to Fig 7a and Fig 7b, the paralleling drill guide (33) has two components, a dental prosthesis attachment device (17') and a drill guide tube (53) connected by a connecting bar (32). The drill guide tube (53) is a hollow tube with cylindrical space (34) and cylindrical wall (35). The cylindrical space (34) has diameter sized big enough to admit a pilot drill and just big enough to fit the dental implant i.e. the same diameter as the cylindrical recess (20) of dental prosthesis attachment device (17) is just right. Both components are fixedly connected such that the two cylindrical cores (20') and (34) are in parallel relationship. The length L is the distance between the two components. This length L is variable to accommodate the various distances between implants that are usually encountered in clinical practice. The length L may vary by having different paralleling drill guides of different lengths L. Or there can be a simple mechanism in place to_v make the length L adjustable. Two common mechanisms employable would be two arms connected by a pivot joint and telescoping tubes secured with fastening means. Suitable materials would be surgical grade stainless steel, titanium or a high performance plastic.

In practice, the first mini implant is placed at a pre-planned location and angulation, usually parallel to an adjacent tooth. After the first implant has been screwed on, the paralleling drill guide (33) with the desired distance L to the next planned implant site is snapped on via the dental prosthesis attachment device (17'). Note here that the external contours of the dental prosthesis attachment device (17') need not be frusto-conical shaped. The dental prosthesis attachment device (17') could be tubular in shape with a cylindrical recess (20) while the external contours are preferably cylindrical in shape but can be of any other shape such as a square. A frusto-conical shape is desirable for direct impression taking purposes, which is not necessary when used in a paralleling drill guide (33). Indeed for adaptation of the prosthesis attachment device (17) for use in a paralleling drill guide (33), the capping (23') is preferable provided but can be dispensed with. The drill guide tube (53) is swivelled onto the desired location. Next a probe with a central pointed end sized to fit into the drill guide tube (53) impressed into the drill guide tube (53) to mark the desired position. The drill guide tube (53) is swivelled away to allow a diamond bur or other such like drill to cut through the gum and into cortical bone at the marked spot. This buys the initial catch for the pilot drill. The drill guide tube (53) is swivelled back again. The pilot drill is inserted through the drill guide tube (53) into the initial purchase in the cortical bone just made. The pilot hole is drilled into the desired depth and will be in parallel relationship with the first implant. When the desired sized implant hole has been 'achieved the mini implant is screwed partway into the bone with aid of the drill guide tube (53). Bone is spongy and deviation of angulation may still occur during torquing.

Fig 8 illustrates the dental prosthesis attachment device (17) in use. ( 36) , (37), and (38) are 3 prosthetic teeth fixed with permanent dental cement to three dental prosthesis attachment devices (17"), (17'), and (17). These in turn are snapped onto three O-ball head mini dental implants (10) which have been screwed through gum (40) and bone (41). These three implants are in parallel relationship which was achieved by use of the paralleling drill guide (33) (Fig 7a). Note that there is loss of bone (41) at location marked (42) and the restored teeth are of different shapes and volumes and should be at optimal occlussal relationship to opposing teeth. The O-ball head mini dental implants (10) are placed so that different ^heights, h, h', and h", of the cylindrical collar (14) protrude beyond the gum line (39). Corresponding different sized dental prosthesis attachment devices (17), (17') and (17') are applied.

In this representative patient, after the three O-ball head mini dental implants (10) have been screwed onto the jaw bone (41) so that appropriate heights (h, h', h") of the cylindrical collar (14) protrude beyond the gum line (39). The three O-ball head mini dental implants (10) were placed in parallel relationship with use of the paralleling drill guide (33). Corresponding dental prosthesis attachment devices (17, 17'-, and 17") were snapped on so that there is some pressure on gum tissue (40). Over a short period of time, this will result in a smooth and healthy gum interface. A rubber dam is slipped over the prosthesis attachment device to grip the mini implant. A direct impression is taken and cast model sent to the lab which would treat it like a normal abutment teeth supported crown and bridge case. A chairside fabrication of a temporary bridge on the three dental prosthesis attachment devices (17", 17' and 17) is snapped onto the O-ball head mini dental implants (10). i

When the lab fabricated bridge comprising prosthetic teeth (36, 37 and 38) is ready patient comes back for fitting. The _^temporary bridge is snapped off and three corresponding dental prosthesis attachment devices (17", 17' and 17) snapped on. If the fitting is correct, the lab fabricated bridge is cemented onto the 3 dental prosthesis attachment devices (17, 17' and 17"). When the cement has set, the bridge comprising prosthetic teeth (36, 37 and 38) is retrieved and all excess cement removed and surfaces polished and glossed. The bridge comprising prosthetic teeth (36, 37 and 38) is snapped on again. Of course, if cement fixation is preferred, excess cement is readily removed and full 'access for cleaning purposes is ensured.

In the first 3 months while awaiting full osseointegration, the health of the gum (40) around the O-ball head mini dental implants (10) is easily gauged by retrieving the bridge comprising prosthetic teeth (36, 37and 38). This is done by snapping off with a sustained pulling force which causes the elastic O-rings (16) to expand and allow the bridge to be released, often with a snapping sound.

The disclosures in this invention, of the dental prosthesis attachment device (17), O-ring insertion/removal tool (25) and paralleling drill guide (33) should further enhance the applications of O-ball head mini dental implants. The teachings of this invention is not limited to one particular embodiment, many adaptations according to the principles set out are possible. Such variations are not to be regarded as a departure from the principles and scopes of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of following claims.

Claims

1. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10), the O-ball head mini dental implant (10) comprising an O-ball head (11), a cylindrical neck (12), a square shoulder (13), a cylindrical collar (14) and a threaded shaft (15) integrally connected in that sequence and wherein the prosthesis mounting device (17) comprises: a housing (7), the housing (7) comprises a continuous peripheral wall (19) having a capping (23) at one end and a base (21) at the other end, with the continuous peripheral wall (19) and the capping (23) defining a cylindrical recess (20) having a roof (9) at the capping (23) and an opening at the base (21); and an annular groove (18) on the surface of the peripheral wall (19) within the cylindrical recess (20), the annular groove (18) located between the roof (9) of the cylindrical recess (20) and the base (21) of the housing (7); and an O-ring (16) insertably seatable in the annular groove (18), wherein the cylindrical recess (20) is adapted to enable cooperative mating between the cylindrical recess (20) of the dental prosthesis attachment device (17) and the cylindrical collar (14) of the O-ball head mini dental implant (10) when the dental prosthesis attachment device (17) is retrievably snapped onto the O-ball head mini dental implant (10); and wherein the depth of the cylindrical recess (20) and the location of the annular groove (18) on the surface of the peripheral wall (19) within the cylindrical recess (20) of the housing (7) are such that when the dental prosthesis attachment device (17) is retrievably snapped on to the O-ball head mini dental implant (10), the O-ring (16) engages the cylindrical neck (12) of the O-ball head mini dental implant (10) and the base (21) of the housing (7) extends to cover part of the cylindrical collar (14) of the mini dental implant (10).

2. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball mini dental implant (10) as in claim 1, wherein the housing (7) is frusto- conical shaped.

3. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the external surface of the peripheral wall (19) is provided with at least one groove (24).

4. A dental prosthesis mounting device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the edges of the external surface of the peripheral wall (19) are rounded off (22).

5. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the base (21) of the prosthesis mounting device (17) extends to cover substantially that part of the cylindrical collar (14) of the O-ball head mini dental implant (10) above the gum line of a patient when the dental prosthesis attachment device (17) is snapped onto the O-ball head mini dental implant (10) implanted into the jaw bone of the patient such that the gum tissue is slightly impinged upon.

6. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim I₅ wherein the base (21) is shaped to conform to the topography of the ridge of the patient.

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7. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 6, wherein the dental prosthesis attachment device (17) is frusto-conical shaped and wherein the base (21) and the opening are circular in shape.

8. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 6, wherein the base (21) has two oppositely positioned arcs (51) of substantially similar length and curvature making up part of the perimetrical edges of the base (21), with the end points of each arc (51) starting from the base (21).

9. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-.ball head mini dental implant (10) as in claim 6, wherein the base (21) has two oppositely positioned arcs (51', 51") making up part of the perimetrical edges of the base (21) with the end points of each arc (51', 51") starting from the base (21); and wherein length and curvature of one arc (51") is longer and larger respectively than the opposing arc (51').

10. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 6, wherein the dental prosthesis attachment device (17) is oblique frusto-conical shaped and wherein the base (21) and the opening are elliptical in shape.

11. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the O-ring (16) is an elastomeric orthodontic ligature size 90 to 130.

12. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 11, wherein the O-ring (16) is an elastomeric orthodontic ligature size 120.

13. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 12, wherein the O-ring (16) is an elastomeric orthodontic ligature size 120; and wherein the O-ring (16) is made of metal and is "C-shaped" to retain the grip and release function.

14. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the O-ring (16) is replaceable when worn.

15. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the O-ring (16) can be removed from the groove (18) on the peripheral wall (19) of the cylindrical recess (20) with the aid of an O-ring removal tool (26) wherein the O-ring removal tool (26) comprises a pin (43) with a hook (46) at one end.

16. An O-ring removal tool (26) as in claim 15, wherein the other end of the pin (43) is connected to a handle (28).

17. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim I₅ wherein the O-ring (16) can be inserted into the groove (18) on the peripheral wall (19) of the cylindrical recess (20) with the aid of an O-ring insertion tool (27) wherein the O-ring insertion tool (27) comprises a pin (29) connected to a handle (28) at one end and to a ball head (30) at the other end, with a sleeve (31) enveloping the pin (29) slidably sliding between the handle (28) and the ball head (30).

18. A dental prosthesis attachment device (17) that can be retrievably snapped onto an O-ball head mini dental implant (10) as in claim 1, wherein the O-ring (16) can be removed from or inserted into the annular groove (18) on the peripheral wall (19) of the cylindrical recess (20) with the aid of an O-ring removal/insertion tool (25); wherein the O- ring removal tool (26) comprises a pin (43) with one end connected to a handle (28) and ending with a hook (46) at the other end; and wherein the O-ring insertion tool (27) comprises a pin (29) connected to the handle (28) at one end and to a ball head (30) at the other end, with a sleeve (31) enveloping the pin (29) slidably sliding between the handle (28) and the ball head (30).

19. The use of the dental prosthesis attachment device (17) of claim 1 as a component of a paralleling drill guide (33), the paralleling drill guide (33) comprises a dental prosthesis attachment device (1.7) as in ajiy of claims 1 to 6 connected fixedly to a spaced apart drill guide tube (53) by a connecting bar (32), the drill guide tube (53) being a cylindrical hollow tube (54) with a cylindrical wall (35) defining a cylindrical space (34) with the axes of the cylindrical recess (20) of the prosthesis mounting device (17) and cylindrical space (34) of the hollow cylindrical tube (54) of the paralleling drill guide (33) parallel to each other.

20. A paralleling drill guide (33) as in claim 19, wherein the internal diameter of the cylindrical hollow tube (54) is sized to accommodate the passage of a pilot drill.

21. A paralleling drill guide (33) as in claim 19, wherein the internal diameter of the cylindrical hollow tube (54) is substantially the same as that of the cylindrical recess (20) of the dental prosthesis attachment device (17).

22. A paralleling drill guide (33) as in claim 19, wherein the length (L) of the connecting bar (32) can be one of the various suitable lengths to accommodate the various distances between O-ball head mini dental implants that are usually encountered in clinical practice.

23. A paralleling drill guide (33) as in claim 19, wherein the distance (L) between the dental prosthesis attachment device (17) and the drill guide tube (53) of the paralleling drill guide (33) is adjustable.