US3750289A

US3750289A - Centric relating device

Info

Publication number: US3750289A
Application number: US00166187A
Authority: US
Inventors: N Guichet
Original assignee: N Guichet
Current assignee: TDY Industries LLC
Priority date: 1971-07-26
Filing date: 1971-07-26
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: DE2236447A1

Abstract

A device is described which can be used to orient, precisely, dental casts in centric occlusion. The device comprises upper and lower frames that have dental cast support means and that are hinged together in a joint along the condylar axis. The joint permits only pivotable movement of the members in a medial plane. One of the frames, preferably the lower, has centering pivot pins with tapered ends that seat in mating recesses in the joint component of the other frame. A centric inspection or gauge block is provided together with index members that can be secured to the frames to permit inspection of the device. An alternative and preferred centric inspection means comprises a pair of blocks, one of which bears at least one index mark and the other of which supports a magnification lens opposite the mark with a calibrated field to observe any inaccuracies in the centric relation of the frames. The device is used to mount the dental casts to their support rings while using check bite means to orient the casts.

Description

United States Patent [191 Guichet Aug. 7, 1973 CENTRIC RELATING DEVICE [76] inventor: Niles F. Gulchet, 320 Olympia PL,

Anaheim, Calif. 92805 221 Filed: July 26,1971

[2i] Appl.No.: 166,187

[52] U.S. Cl. 32/32 [51] Int. Cl. A6lc 11/00 [58] Field of Search 32/32, 19

[56] References Cited UNITED STATES PATENTS 3,221,408 l2/l965 Scullin 32/32 3,466,750 9/1969 Timberlake et al 32/32 3,510,947 5/1970 Tuccillo et al 32/32 2,952,914 9/1960 Sheckelford 32/32 Primary Examiner--Robert Peshock Attorney-Robert E. Strauss [57] ABSTRACT A device is described which can be used to orient, precisely, dental casts in centric occlusion. The device comprises upper and lower frames that have dental cast support means and that are hinged together in a joint along the condylar axis. The joint permits only pivotabie movement of the members in a medial plane. One of the frames, preferably the lower, has centering pivot pins with tapered ends that seat in mating recesses in the joint component of the other frame. A centric inspection or gauge block is provided together with index members that can be secured to the frames to permit inspection of the device. An alternative and preferred centric inspection means comprises a pair of blocks, one of which bears at least one index mark and the other of which supports a magnification lens opposite the mark with a calibrated field to observe any inaccuracies in the centric relation of the frames. The device is used to mount the dental casts to their support rings while using check bite means to orient the casts.

10 Claims, 11 Drawing Figures PATENTEU MIR 7 I975 SHEET 1 0F 3 7 5 0 7. O 9 I H l O m M m o w I m 5 m 4 M II 0 1. I! n E Z I R W 5 I U H I O G 0 l. i Cl 0 IL J 5 Z 5 Z 5 O 6 G 4 5 n n m w w m 6 M O z i i 4 A. I r I I l ll K. 0 7 M. s o 5 A 3 6 Z 3 fimr 4 3 f v 11. I ill wt p 4 K E M 2 a w 5 F \GURE FIGURE 5 FIGURE 2 PATENIEDAUB nan sum 2 or 3 FIGURE 4 PAIENTEU Am: 7 I815 SHEU 3 OF 3 FIGUQE 7 FIG URE 6 F IGURE [0 FIGURE 9 FIGURE 8 E R U G F ATTORNEY CENTRIC RELATING DEVICE DESCRIPTION'OF THE INVENTION Recent advances in dental articulators have resulted in devices which provide a maximum number of adjustable movements to permit faithfull duplication of the eccentric or border movements of a mandible. The dental articulators comprise upper and lower frames that are hinged together at their rear ends with mechanical fossa joints that simulate the fossa-condyle joint of a mandible. Recent articulators such as that described in my copending application, Ser. No. 761 ,596, filed Sept. 23, 1968 now U.S. Pat. No. 3,590,487 achieve a maximum degree of adjustability by fossa guides such as independently adjustable rear wall, superior wall and medial wall guides. Provision for entirely lateral shifting is also present.

All these independently adjustable guides, while essential in permitting duplication of the border movements of a mandible, compromise the precision in the centric orientation of dental casts when they are mounted in the articulator. The settings of the individual guides have tolerances and the centric orientation of the casts can be altered by the cummulative effect of these tolerances. To illustrate, a tolerance of 0.05 millimeters in setting of the immediate side shift adjustment of the medial wall guides is additive with a tolerance of 0.5 in the angular adjustment of the medial wall guides.

In'the design of a useful articulator, some compromise is also made in the rigidity of the frame members and in their assembly. Consequently, users of the articulator who apply excessive force on the lock screws of the adjustable members can force the frames slightly out of a precise centric relationship. The degree of this alteration need only be slight to cause difficulties in the centric fit of the prosthetic devices which are prepared on the instrument.

The recognition that each articulator may have a slightly different centric registration of dental casts mounted in the articulator has resulted in a laboratory practice to retain dental casts on a single articulator throughout the entire preparation of the dental appliance. While this avoids the introduction of errors in the appliance, it ties up an articulator for each case that is prepared in the laboratory and requires an almost prohibitive expenditure for articulators.

It is, therefore, an object of thisinvention to provide a device that can position dental casts in a precise centric relationship. Y

' It is also an object to provide such a device with calibration means to insure that its frame members are in precise centric alignment.

It is a further object of this invention to provide calibration means for rapid and precise checking of the alignment of a dental articulator.

I It is'an additional object of this invention to provide a method of reconstructive dentistry that permits interchange of dental articulators during the preparation of dental appliances.

Other and related objects will be apparent from the following description of the invention.

A-number of the preceding objects are achieved by the centric inspection means of this invention that comprises indexing members which can be detachably secured to the frame members of an articulator. These members have precisely oriented calibration means to permit simple observation of any misalignment of the upper and lower frames of the articulator.

The remainder of the preceding objects are achieved by the aforedescribed centric inspection means and a centric relating device which is formed of upper and lower frames that are hinged together at their posterior along the condylar axis by a joint which permits only pivotable movement of the members in the medial plane. Preferably, the joint has means to retain precision of the alignment of the frames during use which comprises pin means supported by one frame and having tapered ends that seat in mating recesses in the joint component of the other frame.

The centric relating device can be used to orient the dental cast to a precise centric occlusion. The upper cast can be secured to its mounting ring in an articulator or in a centric relating device which has transfer facilities such as condyle mounts for the hinge axis centering pins of a pantograph or face bow. With the upper cast attached to theupper frame of the centric relating device of this invention, a mounting ring for the lower east can be secured to the lower frame of the centric relating device and the lower cast can then be ccmcnted or plastered to this ring, using check bite means to orient the lower east to the upper cast. The resultant casts are precisely in centric orientation since no errors are introduced by the instrument. Thereafter the casts can be transferred to a remote centric relating device and have the same orientation to each other as they had when mounted in the original centric relating device.

In practice, the temporamandibular joint characteristic of the patient is diagnosed by means of a pantograph. The maxillary cast can be transferred to an articulator or to the centric relating device by means of a facebow or pantograph. If first mounted on an articulator, the cast is then removed and transferred to the centric relating device of this invention. The mandibular cast is then mounted in the centric relating device by means of an inter-occlusal check bite record. These mounted casts can now be transferred to any centric relating device and will have the same accurate orientation to each other as originally mounted.

The dentist can now deliver the mounted casts and the value of the settings of the adjustable articulator guides to the dental laboratory. The patient's casts can then be mounted in an articulator for fabrication of the chewing surfaces of the dental appliance and in the centric relating devie for confirmation of fit in the centric related position.

The invention will now be described by reference to the FIGURES, of which:

FIG. I. is an exploded plan view of the centric relating device and its centric inspection means;

FIG. 2 is an elevation view of the device shown in FIG. 1;

FIG. 3 is a view of an alternative index means;

FIG. 4 illustrates mounting of dental casts in the centric relating device; 7

FIG. 5 shows an anterior gauge inspection means;

FIGS. 6 and 7 show face bow mounting brackets at the rear of the centric relating device; and

FIGS. 8-11 show a preferred centric inspection means.

Referring now to FIGS. 1 and 2, the centric relating device comprises an upper frame 10 and a lower frame 12 which are hinged together along the condylar axis by a joint which permits relative movement only by rotation in a medial plane. Each frame carries, at its midportion, means for removably securing a dental cast mounting ring. These means comprise

thumb screws

14 and 16 which are inserted through bores in the frames and which bear threaded studs that engage the cast mounts.

The lower frame is stamped from sheet metal with feet 18 at its anterior end and feet 20 at its posterior end. Outboard wings at the posterior of the stamping are bent upwardly to form upright support means 22 and 24. A cross bar 26 is mounted between the

supports

22 and 24 with the upper ends of these supports fitted into grooves 28 which are milled into the cross bar 26. The cross bar carries

upright posts

30 and 32 at its opposite ends; preferably these are integral with the bar. The posts are bored at 31 and 33 with a diameter to fit bearing pins 34, and are tapped to receive set screws 35 which are used to lock pins 34 in bores 31.

The upper frame is formed of plate 36 which has its posterior end rolled downwardly to form a lip 38 which also bears index means such as key 40 along its rear face. The joint component of the upper frame comprises shaft 42 which has keyway means such as groove 44 to seat key 40 for precise alignment of plate 36 thereto. Screws 46 can be used to fasten the plate to the shaft. The shaft is of the proper length for mounting between the inside faces of the

posts

30 and 32, and has tapered recesses 48 milled into its opposite ends. The pins 34 have tapered ends 50 that mate with these recesses so that the shaft 42 can be precisely oriented along the centerline passing through

bores

31 and 33. Alternatively, pins 34 can be straight and bores 31 and 33 can be slightly oversized. Several threaded bores can be tapped into

posts

30 and 32 transverse to bores 31 and 33 and set screws can be set therein. Pins 34 can then be moved into exact alignment with the set screws which can thereafter be covered with a potting compound.

FIGS. 6 and 7 illustrate a modification of the centric relating means which bears a pair of sliding brackets 140 in dovetailed grooves 141 that are milled into the rear surface of

posts

30 and 32. A set screw 142 is provided in a tapped bore in the top of the posts which intersects the groove so that the brackets can be locked at any extension along the grooves 141. An index mark 143 is provided to register the extension of the brackets on scale 144 which is calibrated on the brackets. The brackets bear an outboard wing 145, shown in FIG. 7, which has an indentation 146 on the hinge axis of the device to permit mounting of centric pins of a face bow.

The scale 144 is calibrated to correspond to varied intercondylar distances from 50 to about 70 millimeters. These brackets permit the centric relator to be used to mount the maxillary cast directly from the facebow or pantograph. This can be accomplished by sliding the brackets 140 outwardly until they engage the hinge axis centering pins of the face bow on which is supported the maxillary cast. The centering pins are hooked into the recesses 146 and the anterior of the face bow is supported at the correct vertical spacing, e.g., by use of a'reference plane support rod such as that described in my prior US. Pat. No. 3,350,782. The upper cast can then be plastered to its mounting ring. Thereafter the lower east can then be plastered to its mounting ring, using check bite means such as 86 to 88 to orient the casts to each other. These check bite means are shown and described in regard to FIG. 4.

Referring once again to FIGS. 1 and 2, the rest of the device will be described. Plate 36 is slotted at 54 and block 52 is mounted therein with thumb screw 55 which can be tightened against washer 57 to bind the block in slot 54. This block is bored and fitted with incisal pin 56. The anterior of frame 12 is slotted at 58 and 60. A block 62, which comprises rest means for incisal pin 56, is milled with key means 64 which mates with the compound slot of frame 12. The block is also bored and tapped at 66 to receive thumb screw 68. The thumb screw can be tightened to compress the upper face of its boss 70 against frame 12 and thereby lock the block in the slot.

One centric inspection means which is an accessory for use with the centric relating device or with a conventional articulator comprises a gauge block 71 and an index member such as 72 which have tapped bores that can be engaged by

thumb screws

14 and 16 to permit their removable attachment to

frames

12 and 10, respectively. The upper end of block 71 has a central bore 75 with slightly inclined side walls, e.g., at an angle of about to preferably about 89.5". The index member 72 is of identical diameter to block 71 with a raised boss 77 on its lower face which precisely fits into bore 75 with a minimal tolerance, e.g., 0.001 inch. To provide a varied degree of tolerance in the inspection means, one or more additional index members can be provided having increased tolerances, e.g., a second index member can be provided having a tolerance of: 0.003 inch for checking the alignment of conventional articulators. Another useful index member for use with the block is shown in FIG. 3 as a flat disc 79 which has a diameter equal to that of block 71 and a thickness identical to the gap between the upper frame and top of block 71 when the latter is placed in an articulator. The disc also has bores 74 to engage pins 73 of the frame, similar to index member 72 and block 71. A calibration line 78 can be scribed on the disc to index with a similar line on block 71. This disc and block could also be machined with a predetermined separation, e.g., 0.001 inch, and a thickness gauge could be inserted into the gap between them to check the alignment.

A preferred centric inspection means which has an integral optical viewer is illustrated in FIGS. 8 through 11. This comprises a pair of blocks and 121 which can be removably attached to the lower and upper frames, 12 and 10, respectively, of the centric relating device shown in FIGS. 1 and 2. The blocks can also be used with a conventional articulator to check its centric relationship. The blocks are bored and tapped at to permit them to be attached to the upper frame 36 and the lower frame 12; see FIG. 1. The lower block has an upper face or table 122 which is shown in FIG. 9. The table bears a pair of index marks 123 and 124 at its outboard wings which form the stages for the microscopes carried by the upper block 121. The marks can be cross lines or single lines that are perpendicular to each other as shown in the field of view; see FIG. 10.

The upper block 121 supports optical viewing means 126 and 127 which are positioned opposite index marks 123 and 124. The viewing means comprises an eye piece 128 with its lens 129 and a magnifying lens 130 which is supported in tube 131. Suitable magnification which can be achieved by any suitable lens system can be from to 100X magnification, preferably about 40X. Tube 131 is fitted into a bore in the outboard wing of block 121. The viewing means also has a calibrated field such as that shown in FIG. 8 with scales that are calibrated in suitable subdivisions such as lines representing about 0.001 inch.

The device shown has index marks and cooperating lenses at each side for maximum accuracy. If desired, a single index mark could be used if placed on the longitudinal axis of the instrument and used with a lens system that would permit viewing of the mark between the frames.

FIG. 4 shows centric orientation of dental casts in the relating device. Maxillary cast 80 has been plastered to its mounting ring and this cast is secured to frame 10 with thumb screw 14. The lower east mounting ring 84 is secured to frame 12 by screw 16 and the lower east in moved beneath the maxillary cast. Check bite means 86 through 88 are placed between the engaging teeth of the casts to orient the casts to each other. These check bite means comprise wax impressions that are obtained by placing small chunks of wax on several, selected location of the patients teeth and then having the patient close his jaw. As shown, the casts are of teeth prepared for inlays and the checkbites are made on the cut teeth with the jaw in centric occlusion so that there is no vertical separation between the teeth. When checkbites are prepared which require the jaw to be slightly open, an adjustable pin such as 106 of FIG. 5 can be substituted for pin 56 which is of fixed length. The lower east is aligned by the check bite means and plaster 90 is placed between the mandibular cast and mounting ring 84 to secure the cast to the ring. Thereafter, the centric relating device can be opened and the casts removed and mounted in an articulator having adjustable fossa guides. The articulator, of course, should have cast mounting means such as 14 and 16 which are positioned on its frames at the same relative positions as

screws

14 and 16 of the centric relating device.

Because of the rigidity in construction of the centric relating device and because of the absence of any adjustable fossa guides that permit eccentric or border movements of the casts to all jaw positions, the dental casts will be in precise orientation to each other. It is desirable, however, to have means to periodically check the precision of the centric relating device. Such means are shown as the gauge block 71 and index means 72 of FIGS. l-3, or, preferably,-the inspection blocks shown in FIGS. 8-11 as 120 and 121 which can be secured to the lower and upper frames, respectively. If the frames are out of alignment, the direction and the amount of the misalignment can be observed. When the gauge block 71 and index means 72 are used, misalignment of the frames will prevent their closing and pin will be retained from engagement with block 62. This simple inspection performed periodically on the device, insures that it is in precise alignment throughout its use. A similar check can be made on a conventional articulator by securing block 71' to the lower frame of an articulator and the index means 72 or 79 to the upper frame, then closing the articulator and observing the engagement between the index member of the disc and the blockf'lhe blocks 120 and 121 can also be used to check the alignment of an articulator by securing them to the articulator in the manner previously described and directly observing through optical piece 128 the degree of misalignment, if any is present.

FIG. 5 shows a centric inspection means which comprises pin 115 that can be used to check the alignment of the anterior of an articulator. The pin is shown in position in an articulator such as disclosed and claimed in my copending application, Ser. No. 761,596, now US. Pat. No. 3,5 90,487. This articulator has an upper frame 102 and a lower frame which are adjustably hinged together at their posterior ends and are retained in separation by by vertical stop means that comprises incisal pin 106 which is secured to the upper frame by adjustable bracket 103 and which rests on block 109 which is secured to the lower frame. The lower end of pin 106 bears a guide member 108 which has a sliding shoe with scale means to indicate the position of the shoe on the pin. An incisal table 110 comprising wing members that can be inclined along the longitudinal axis of the instrument and along an axis passing through pin 11] is secured to the lower frame by screw 112.

Bracket 103 is conventional is construction and provides for an adjustable separation of the anterior of the frames. This is formed from block 105 that bears pin 106 and mounting bracket 104 which is secured to frame 102 by screw 113. The mating faces of block 105 and mounting bracket 104 are formed on a radius from the condyle axis of the articulator. The arcuate face of bracket 104 is bored and tapped to receive the threaded end of screw 107. Block 105 has a vertical groove extending through its thickness and the threaded shank of 107 extends through the groove so that the boss 117 of screw 107 can be clamped against the outside face of block 105 to lock the block tightly to bracket 104.

A calibrated scale is provided on one of the

members

104 or 105 and the other member carries an index mark. During use the members can become slightly misaligned so that the frames are not precisely parallel when the index mark registers at the zero calibration mark on the scale. Accordingly, an embodiment of the invention comprises an inspection means such as pin 1 15 which is a precisely machined pin that providesthe exact vertical separation of the

frames

100 and 102. The surfaces of the frames should be machined to provide

smooth engagement surfaces

116 and 117 for the ends of pin 115. If desired, an index means such as a scribed mark, recessed bore or slightly raised boss can be provided on the

frames

100 and 102 so that the ends of pin can be precisely indexed to the frames. The zero calibration on the scale shown on block 105 can be checked with pin 115 held between the frames as indicated in FIG. 5. In this manner, precise alignment of the anterior of the articulator can also be maintained.

If an accurate reading of the degree of misalignment of the frames of an articulator or of the centric relating device is desired, the

blocks

120 and 121 can be used. If desired, however, gauge block 71 and its indexing member 72 can be used together with sighting means that can be a simple pocket microscope or comparator. This unit is a small hand held microscope with a 20 to about 40 power magnification and with a graduated field of vision'that is divided into 0.001 inch units. Preferably, the pocket comparator is provided with its own, integral light source such as a small battery powered flashlight.

The centric relating device can also be used in the fabrication of dental appliances to finalize the centric occlusion of the appliance, or its pattern. As previously mentioned, the device is used to orient, precisely, dental casts which are cemented to their mounting rings such as 82 and 84 of HO. 4. The casts are then transferred to an articulator such as that shown in my US. Pat. No. 3,590,487. This articulator has its frames hinged together with condyle-fossa joints which permit the movement of the frames in a manner that simulates the border movements of a mandible. The pattern of the dental appliance is fabricated on the casts using the articulator to move the casts in their eccentric or limiting border movements to all jaw positions. After the pattern has been developed on the articulator in this manner, the casts bearing the developed pattern are then remounted in the centric relating device and the frames of this device are closed into the centric occlusion to finalize the pattern and insure that there will be no interference when the appliance is mounted in the patients mouth.

The invention has been described with regard to specifically illustrated embodiments. It is not intended that the invention be unduly limited by this disclosure, but rather it is intended that the invention be defined by the means, and their obvious equivalents, and the method steps and their obvious equivalents set forth in the following claims.

I claim:

1. The method for orienting dental casts in precise alignment and securing said casts to means permitting their removable attachment to opposite frames of a dental articulator having adjustable condyle-fossa guides which permit eccentric movement of said frames to simulate eccentric movement of a mandible which comprises: positioning said dental casts into precise alignment on a centric relating device having upper and lower frames secured together by joint means permitting relative movement of said frames only by rotation in a medial plane, permanently securing said casts in said alignment by cementing them to detachable mounting means carried by said relating device, removing the resulting mounted casts from said relating device and securing said mounted casts to the frames of said articulator.

2. The method of claim 1 wherein both said casts are cemented to mounting means attached to the frames of said relating device.

3. The method of claim 1 wherein a pattern of a dental appliance is fabricated on said casts in said articulator, said casts bearing said pattern are remounted in said regulating device and the frames of said device are closed together to finalize the centric occlusion of said pattern.

4. The combination of a dental tool useful for supporting dental casts in opposed centric orientation comprising an upper frame and a lower frame fastened together at one of their ends by joint means that permits relative rotation of said frames in a medial plane and supported at their opposite ends by vertical stop means, dental cast attachment means carried in opposed relationship at the mid-portion of each of said frames to secure and index dental casts thereto, and centric inspection means comprising an index member detachably mounted on one of said frames by said attachment means and a gauge block member maintained in opposed relationship thereto by the attachment means on the other of said frames, said index member and gauge block member bearing cooperating indices to register, precisely, the centric orientation of said frames.

5. The combination of claim 4 wherein said dental tool is a dental articulator with condylar joint means which permit duplication of mandibular border movements.

6. The combination of claim 4 wherein said dental tool is a centric relating device having joint means which permit only said relative rotation in a medial plane.

7. The combination of claim 6 wherein the joint means of said centric relating device is positioned along the condylar axis of said device.

8. The combination of claim 6 wherein said joint means of said centric relating device comprises a pair of pins having tapered inboard ends which are supported by one of said frames and project into tapered recesses carried by the other frame.

9. The method for attaching dental casts to their mounting means for precise centric occlusion when the mounting means are secured to opposite frames of an articulator having adjustable eondyle-fossa guides which permit eccentric movement of the dental casts to simulate the border movements of a mandible which comprises: cementing one of the pair of maxillary and mandibular casts to mounting means secured to a frame of the articulator while supporting the cast with a face bow to orient the cast to the condylar axis of said articulator, removing the assembly of said mounting means and cast from said articulator and securing said assembly to one frame of a centric relating device which has no provision to permit eccentric movement of dental casts attached thereto, securing dental cast mounting means to the other frame of said device, poritioning the other of said dental casts in centric occlusion to the cast in said assembly with check bite means placed between said casts and cementing said other dental cast, in such position, to the mounting means secured to the other said frame.

10. The method of claim 9 wherein the maxillary cast is cemented to its mounting means in the articulator and the mandibular cast is cemented to its mounting means in the centric relating device.

I i i i 4

Claims

3. The method of claim 1 wherein a pattern of a dental appliance is fabricated on said casts in said articulator, said casts bearing said pattern are remounted in said relating device and the frames of said device are closed together to finalize the centric occlusion of said pattern.

9. The method for attaching dental casts to their mounting means for precise centric occlusion when the mounting means are secured to opposite frames of an articulator having adjustable condyle-fossa guides which permit eccentric movement of the dental casts to simulate the border movements of a mandible which comprises: cementing one of the pair of maxillary and mandibular casts to mounting means secured to a frame of the articulator while supporting the cast with a face bow to orient the cast to the condylar axis of said articulator, removing the assembly of said mounting means and cast from said articulator and securing said assembly to one frame of a centric relating device which has no provision to permit eccentric movement of dental casts attached thereto, securing dental cast mounting means to the other frame of said device, poritioning the other of said dental casts in centric occlusion to the cast in said assembly with check bite means placed between said casts and cementing said other dental cast, in such position, to the mounting means secured to the other said frame.