ADJUSTABLE MOUNTING DEVICE FOR A DENTAL ARTICULATOR

Abstract: The adjustable mounting device (20) comprises two superposed plates (30, 40) in sliding relationship. One of the plates (40) is pivotally connected to the articulator (10). A first mechanism (60) is provided to selectively slide and lock in position one plate (30) relative to the other plate (40) while this other plate (40) is provided with a second mechanism (70) to selectively rotate and lock the device in position with reference to the articulator (10). This mounting device (20) replaces one or both conventional fixed mounting plates in an articulator (10) to provide adjustability between the lower and upper parts of the dental cast (12).

Description: ADJUSTABLE MOUNTING DEVICE FOR A DENTAL ARTICULATOR Dental articulator have been known in the art for many years now. In brief, a dental articulator (sometimes called "mandibular position variator") is used to simulate the movement uf the mandible relative to the maxilla using a two-part dental cast of a patient. Each part of the dental cast is mounted in the dental articulator by means of a corresponding mounting plate on which it adheres. The mounting plates are connected to respective arms of the dental articulator by thumbscrews. A common problem wiih mounting plates used hitherto is that they are fixed and it is thus difficult, for instance, to change the initial relative position of the opposite dental cast parts. US-A-4,391 ,589 to Monfredo et al. teaches a structure which, aέ best seen Figs. 4 and 5, has a plate or cast mount (28) which is pivotal about a threaded shaft (40) and mounted so as to be slidable along a slot (36) which is formed a cantilever (26). A relatively large diameter thumb screw or knob (44) is connected to the bottom of the shaft (40) so that the cast mount (28) can be released for both sliding and rotational movements. A single thumb screw (68) is used to lock the cast mount (28) in position once adjustment has been made and the large diameter knob (44) has been tightened. As can be appreciated, this device features an arrangement which allows two degrees of freedom, one in the form of rotation and the other in the form of linear sliding motion along slot (36). However, the rotational motion and the sliding motion are made by hand. It further requires the use of a support (112) to connect the cast mounting assemblies (10,12) to the articulator (2) and it cannot be installed on existing articulators without important modifications. US-A- , 687,442 to Wong discloses, in Figures 9 and 10, an arrangement which allows each of the plate arrangements to have at least three degrees of freedom. The plates can be moved linearly by operating both screws simultaneously or can be pivoted about either of two parallel axes depending on which of the two screws are rotated. One of the two plates is also pivotally mounted thus providing the combination of plates with up to ten degrees of freedom. However, the large number of degiees of freedom which are possible with the Wong arrangement renders it almost impossible to pi ovide suitable scales by which the relative movement between the two plates can be measured. Wong teaches the use of specific axes to enable translational and rotaϋonal adjustments of the position of the dental cast in an articulator while minimizing the need for compensating adjustments to the position of the dontal cast in axes that are not being adjusted. A removable grid must be used as a reference system to measure the adjustments to the position of the cast. Moreover, the Wong arrangement does not provide a mounting device that can be directly used on an existing articulator. US-A-2,731 ,723 to Br ndhandler teaches a mounting device with two superposed plates. The upper plaie (24) can be moved sidewards with reference to the lower plate (19) by using a screw mechanism (56,57,58,59) on the side thereof. A scale (26) is provided to measure the lateral movements. Means are also provided to move the plates up and down. Screws (29) and corresponding slots (28) are used to secure the upper plate (24) relative to the lower plate (19). The object of the piesent invention is to provide a mounting device that replaces one or both conventional fixed mounting plates in a dental articulator to provide adjustability between the lower and upper parts of the dental cast. According to the present invention, there is provided an adjustable mounting device for use with a dental articulator of the type having two opposite arms, at least one arm being provided with a pivot screw and an adjacent peg. The mounting device comprises a first plate having opposite first and second sides, a second plate having opposite first and second sides, the first side of the first plate being superposed to the first side of the second plate and in sliding relationship therewith. The second side of the second plate comprises a threaded pivot bore for receiving the pivot screw of the dental articulator. A first graduated scale is provided for measuring displacements of the first plate relative to the second plate. The device is characterized in that it further comprises a first screw mechanism to selectively slide and lock in position the first plate relative to the second plate, the first mechanism comprising a first screw operatively connected to one of the plates and in mesh with a threaded element rigidly attached respectively to the other of the plates so that the first plate is slid relative to the second plate upon rotation of the first screw. A second screw mechanism is used to selectively rotate and lock in position the second plate relative to the dental articulator, the second mechanism comprising a second screw in mesh with the second plate and operatively connected to a holding element located at one free end of the second screw, the holding element being connected to one peg of the dental articulator so that the second plate is pivoted relative to the dental articulator upon rotation of the second screw. A second graduated scale is also provided for measuring angular displacements of the second plate relative to the dental articulator. A non restrictive description of preferred embodiments will now be given with reference to the appended drawings, in which: FIG. 1 is a side perspective view of a mounting device according to a possible embodiment of the present invention, showing one mounting device installed in a dental articulator and bearing a corresponding part of a dental cast. FIG. 2 is a front perspective view of the mounting device in FIG. 1 , showing an example of an angular displacement of the device with reference to the dental articulator. FIG. 3 is an enlarged front perspective view of the mounting device in FIG. 1 , showing an example of a relative sliding movement between the plates. FIG. 4 is a bottom view of the second plate of the mounting device shown in FIG. 1. FIG. 5 is a top view of the second plate shown in FIG 4. FIG. 6 is a bottom view of the first plate of the mounting device shown in FIG. 1. FIG. 7 is a side exploded perspective view of the mounting device shown in FIG. 1. The following is a list of the reference numerals, along with the names of the corresponding elements, that are used in the appended drawings and in the description. 10 dental articulator 12 dental cast 14 arms (of the dental articulator) 16 pivot screw (thumbscrew) 18 pegs 20 mounting device 20' mounting plate (PRIOR ART) 30 first plate 32 first side (of the first plate) 34 second side (of the first plate) 36 recesses 38 tenon 39 flange 40 second plate 42 first side (of the second plate) 44 second side (of the second plate) 46 pivot boie 48 opening 50 mortise 52 slot 60 first mechanism 2 first screw 4 threaded element 6 longitudinal opening (of the tenon 38) 0 second mechanism 72 second screw 74 holding element 76 slot 80 first graduated scale 80A, 80B vernier 82 second graduated scale 82A, 82B vernier Referring to FIG. 1 , th<)re is shown an example of a dental articulator (10). A two-part dental cast (12) is located between arms (14) of the articulator (10). FIG. 1 shows the lower part of the dental cast (12) held by a mounting device (20) according to a preferred embodiment of the present invention, while the upper part of the dental cast (12) is held by a conventional mounting plate (20') as found in the prior art. In both instances, they are connected to the corresponding arms (14) of the articulator (10) by means of thumbscrews (16). Of course, the positions of the mounting device (20) and the mounting plate (20') can be inverted. It is also possible to use two mounting devices (20) on the same articulator (10), one holding the upper part of the dental cast (12) while the other is holding the lower part thereof. These two mounting devices (20) may also be two different models, depending on the specific needs. There are several embodiments for the present invention, all of which allow at least one part of the dental cast (12) to be moved relative to the other. The embodiment shown in FIGS. 1 to 7 combines every element needed for building the various other embodiments. The mounting device (20) may be moved according to two main degrees of freedom, one being a rotation around the vertical axis (FIG. 2) and the other being a translation in the horizontal plane (FIG. 3). The various embodiments are subcombinations of these movements. The embodiment shown in the drawings will be first explained. As best shown in FIG. 7, the mounting device (20) comprises a first plate (30) superposed to a second plate (40) in a sliding relationship. The first plate (30) has a first side (32) and a second side (34) opposite the first side (32). The second plate (40) also has a first side (42) and a second side (44) opposite the first side (42). The first side (32) of the first plate (30) is interconnected to the first side (42) of the second plate (40) as further explained hereinafter. As for the second side (34) of the first plate (30), it preferably comprises a plurality of recesses (36) on which the corresponding part of the dental cast (12) adheres. The recesses (36) provide an increased surface for the plaster that holds the dental cast (12). The present embodiment of the mounting device (20) combines the aforesaid two degrees of freedom. The first degree of freedom is the relative sliding movement in one direction between the first (30) and the second plate (40). This direction is preferably the lateral direction with reference to the articulator (10) but any other may be chosen. The second degree of freedom is the relative rotation between the second plate (40) and the corresponding arm (14) of the articulator (10) on which the second side (44) of the second plate (40) is pivotally connected (see FIG. 2). Of course, the first plate (30) is also rotated at the same time since it is supported by the second plate (40). The pivot attachment between the second plate (40) and the corresponding arm (14) is preferably achieved by a threaded pivot bore (46) located on the second side (44) of the second plate (40). The pivot screw (16), projecting out of a hole in the corresponding arm (14), is screwed into to bore (46) but not too tight in order to allow the rotation. As best shown in FIG. 3, the first (30) and the second plates (40) are interconnected in a sliding relationship. This is preferably achieved by a dovetail-like tenon (38) projecting from the first side (32) of the first plate (30). The tenon (38) fits into a corresponding mortise (50). Additionally, a flange (39) also projects from the first side (32) of the first plate (30) and extends parallel to the tenon (38). The flange (39) fits into a corresponding slot (52). A first mechanism (60) is provided to selectively slide and lock in position the first plate (30) relative to the second plate (40). Preferably, the first mechanism (60) comprises a screw (62) operatively connected to the first plate (30), more particularly to the tenon (38) in which it extends longitudinally and only rotates on itself with reference to it. The screw (62) is in mesh with a corresponding threaded element (64) rigidly attached to the second plate (40). Because the screw (62) extends in the tenon (38), the tenon (38) has a longitudinal opening (66) to allow the screw (62) to reach the threaded element (64) and to allow the tenon (38) to slide in spite of the presence of the threaded element (64) (see FIG.6). The screw (62) may be operated by means of the thumbscrew knob. Providing the screw (62) with very fine threads generates a self-locking mechanism that will not move unless the screw (62) is operated on purpose. The rotation and lock ; ng of the device (20) with reference to the articulator (10) is achieved by a second mechanism (70). Preferably, as shown in FIG. 5, the second mechanism (70) comprises a screw (72) in mesh with a lateral side of the second plate (40) and operativ ely connected to a holding element (74). The holding element (74) is located at a free end of the screw (72) inside a slot (76) in the second plate (40). The holding element (74) is connected to a fixed location, for example to one of the alignment pegs (18) usually already provided on the articulator (10) (see FIG. 7). To prevent the other peg (18) from interfering, if any, there is provided a wide opening (48) in the second side (44) of the second plate (40) so that the latter may be pivoted freely within the desired range of angles. Like the screw (62) of the first mechanism (60), the screw (72) may be operated by means of a thumbscrew knob and providing it with very fine threads generates a self-locking mechanism that will not move unless the screw (72) is operated on purpose. In order to keep track of the translation and the rotation, the mounting device (20) may further comprise a first graduated scale (80) for measuring displacements of the first plate (30) relative to the second plate (40), and a second graduated scale (82) for measuring angular displacements of the second plate (40) relative to the dental articulator (10). Preferably, each of these scales (80,82) comprises a vernier (80A, 80B, 82A, 82B) to increase accuracy in the measurements. The embodiment described hereinabove comprises two degrees of freedom, but there are additional embodiments with only one degree of freedom. For instance, it is possible to provide only the second plate (40) without the first plate (30). In that case, the first side (42) of the second plate (40) has the recesses (36). Another possible embodiment is the one where the first (30) and the second plate (40) are provided, but only the first mechanism (60) is present, the second plate (40) being fixedly connected to the articulator (10) like in the prior art. Moreover, it is possible to superpose more than two plates and provide additional mechanisms to add other degrees of freedom, such as additional sliding directions in the horizontal plane.

Claims: CLAIMS: 1. An adjustable mounting device (20) for use with a dental articulator (10) of the type having two opposite arms (14), at least one arm (14) being provided with a pivot screw (16) and an adjacent peg (18), the mounting device (20) comprising: a first plate (30) having opposite first (32) and second sides (34); a second plate (40) having opposite first (44) and second sides (42), the first side (32) of the first plate (30) being superposed to the first side (44) of the second plate (40) and in sliding relationship therewith, the second side (34) of the second plate (40) comprising a threaded pivot bore (46) for receiving the pivot screw (16) of the dental articulator (10); a first graduated scale (80) for measuring displacements of the first plate (30) relative to the second plate (40); the device (20) being characterized in that it further comprises: a first screw mechanism (60) to selectively slide and lock in position the first plate (30) relative to the second plate (40), the first mechanism (60) comprising a first screw (62) operatively connected to one of the plates (30,40) and in mesh with a threaded element (64) rigidly attached respectively to the other of the plates (30,40) so that the first plate (30) is slid relative to the second plate (40) upon rotation of the first screw (62); a second screw mechanism (70) to selectively rotate and lock in position the second plate (40) relative to the dental articulator (10), the second mechanism (70) comprising a second screw (72) in mesh with the second plate (40) and operatively connected to a holding element (74) located at one free end of the second screw (72), the holding element (74) being connected to one peg (18) of the dental articulator (10) so that the second plate (40) is pivoted relative to the dental articulator (10) upon rotation of the second screw (72); and a second graduated scale (82) for measuring angular displacements of the second plate (40) relative to the dental articulator (10). 2. An adjustable mounting device (20) according to claim 1 , characterized in that the second side (44) of the second plate (40) comprises an opening (48) to accommodate a second peg (18) adjacent the pivot screw (16) of the arm (14) of the articulator (10) so that the second plate (40) be rotated freely within a range of angles. 3. An adjustable mounting device (20) according to claim 1 or 2, characterized in that each of the first (80) and the second graduated scale (82) comprises a vernier.

Inventors: LANDRY ALAIN, LANDRY, ALAIN
Applicants: LANDRY ALAIN, LANDRY, ALAIN
Application year: 1997
Main classification: A61C11
IPC codes: A61C11