WO1995009581A1

WO1995009581A1 - Dental articulator

Info

Publication number: WO1995009581A1
Application number: PCT/FR1994/001178
Authority: WO
Inventors: Serge Sifaoui
Original assignee: Serge Sifaoui
Priority date: 1993-10-07
Filing date: 1994-10-07
Publication date: 1995-04-13
Also published as: FR2710832A1; FR2710832B1

Abstract

Dental articulator of the type comprising a horizontal baseplate having a first arm for fixing a mould of the lower jaw, a substantially vertical post secured to one of the base ends, a second arm for fixing the mould of the upper jaw being hinged to the upper end of said post. Each arm (2, 7) comprises means for fixing, on the face turned towards the other arm, a ball joint (20) of substantially hemispheric shape or a socket (25) of complementary shape, while each mould (22, 23) to be fixed to an arm is associated with a disk (24) comprising respectively a ball joint (25) or a socket (20), according to whether the arm (2, 7) has a ball joint (20) or a socket (25). According to the invention, the unit composed of a ball joint (20), a socket (25) and a mould (22, 23), is made integral by bonding after positioning of the mould. The vertical post (3a, 3b), on which is articulated the second arm, is telescopic and lockable in the desired position.

Description

DENTAL ARTICULATOR

The present invention relates to a dental articulator. A dental articulator is a mechanical device, the function of which is to reproduce the movements of the temporomandibular joint, for the purpose of making dental prostheses, or for the purpose of analyzing the occlusion between the upper teeth and from the bottom of a jaw, and generally between a mandible and a maxilla.

An articulator comprises two parts, articulated one on the other in the manner of the two jaws of a clamp, on each of which is fixed a plaster molding, reproducing respectively the shape of the maxilla and the shape of the patient's mandible, whose teeth are analyzed or for which a prosthesis should be produced. There are articulators that reproduce only the opening and closing movements of the mouth, which are called occluders. There are articulators, called semi-adaptable, which reproduce the opening and closing movements, as well as the lateral movements. It is these articulators which are the most used, because they reproduce more finely all the movements of a jaw. In practice, the mandible and maxilla are molded of the jaw to be analyzed, or which must be fitted with a prosthesis. From these moldings, in negative, plaster molds are produced positively reproducing the shape of the maxilla and the mandible respectively. It is advisable to fix these two moldings on the two branches of the articulator in order to analyze their movements, with a view to producing a perfectly adapted prosthesis.

A first solution consists in carrying out the fixing of each molding on one of the branches of an articulator by means of plaster. This fixation using plaster is carried out after coincidence of the two moldings, with the possibility of giving them, thanks to the malleable nature of the plaster, the desired orientation, in compliance with the rules of dentistry. However, this solution is not satisfactory, insofar as it is a long technique of implementation, which requires about thirty minutes for the fixing of the two moldings on the articulator, which is messy, since plaster forms dust, therefore requiring the use of a specific room, and which does not have great precision since, during its drying, the plaster undergoes an expansion which results in an occlusion error which can vary from 2 to 7 tenths of a millimeter in depending on the nature of the plaster used. However, according to the authors, the proprioception of the human tooth is requested by values varying from 5 to 20 microns. This plaster fixing technique, used for making prostheses, is not used in dental offices, given the time taken to fix the moldings and the dirty nature of the plaster. It has been imagined to produce articulators in which the fixing of each molding is carried out mechanically. To this end, each branch of the articulator comprises a cradle intended to receive a molding, with tightening means by screw, or by eccentric. However, it has been observed that, during the implementation of the tightening, the tightening action results in a displacement of each molding with respect to the desired position, so that one does not yet obtain the precision required. In addition, these mechanical fastening devices do not allow the implementation of a facial arch. However, it is interesting, for the precision of the work, to implement a facial arch whose function consists in positioning in space the upper jaw relative to the plane of Frankfurt. This plane, which is defined by the two condyles and the suborbital point, usually forms an angle with the occlusion plane of the order of 8 to 15 °, this angle being open towards the front.

Documents DE-A-2 922 087 and EP-A-0 21 1 788 each relate to a dental articulator comprising a horizontal base equipped with a first branch intended to be used for mounting a molding of a mandible, an arm substantially vertical fixed to one end of the base, at the upper end of which is articulated around a horizontal axis, a second branch intended to be used for mounting a jaw molding, each branch comprising means for fixing, on its face turned towards the other branch, of a ball joint of substantially hemispherical shape or of a cup of complementary shape, while each molding intended to be fixed on a branch is associated with a disc equipped respectively with a bowl or a ball joint, depending on whether the branch is equipped with a ball joint or a bowl. In these two articulators, the vertical positioning of the two moldings relative to one another is carried out mechanically, with large clearances, at the level of their attachment to the two branches.

The object of the invention is to provide an articulator of the semi-adaptable type, in which the fixing of the moldings on the articulator can be carried out without using plaster, in a precise manner, and very quickly. Another object of the invention is to make this articulator compatible with the use of a facial arch to position in space the molding corresponding to the upper jaw relative to the plane of Frankfurt.

To this end, the dental articulator which it relates to, of the aforementioned type, is characterized in that the assembly consisting of a ball joint, a bowl and a molding being secured by gluing after positioning the molding, and in that the vertical arm on which is articulated the second branch being telescopic, and biocable in the desired position.

It is thus possible to fix the two moldings corresponding respectively to the maxilla and the mandible, in the desired position, thanks to a latitude of adjustment in 3 dimensions. The height is adjusted by sliding the vertical arm, to take into account the thickness of the moldings, while the adjustments in the other planes are obtained by pivoting the ball joints inside the bowls.

In practice, the molding of the jaw is first of all carried out, with its inclination according to the occlusion plane, taking account of the angle between the occlusion plane and the Frankfurt plane. When the molding is in the desired position, it is fixed by gluing, which immobilizes it immediately and definitively thanks to the performance of the glue. The molding of the mandible is then positioned taking into account the position of the molding of the maxilla before being immobilized in the same way by gluing the patella, the cup and the molding with glue.

According to a characteristic of the invention, the means for fixing the two moldings on the two branches are offset with respect to each other, in a direction longitudinal to the two branches, those ass s to! - ^• ; first branch being closer to the vertical arm than those associated with the second branch. This offset is advantageous because it makes it possible to take into account the morphological offset of the maxilla relative to the mandible, and the inclination of the occlusal plane relative to the Frankfurt plane.

This longitudinal offset of the means for fixing the two moldings is of the order of 15 to 20 mm.

In order to avoid any risk of shifting of the moldings during their fixing to the articulator, the means of fixing on each branch of a bowl or a ball joint are constituted by a rod of triangular section integral with the bowl or the ball joint considered and by an opening of the same section made in the branch considered, perpendicular to the branch, that is to say substantially vertically, into which opens transversely a pressure screw oriented along a height of the opening in the direction of l 'one of the peaks.

When a rod of triangular section is tightened, one exerts a pressure on one of the sides of this one, which comes to be positioned in a safe way in the triangular opening at the level of the top of the triangle located on the side opposite to the base of the triangle into which the pressure screw opens.

Advantageously, each bowl has grooves made on its inner face and connecting its bottom to its peripheral edge.

These grooves allow the migration of the glue during the fixing operation of the assembly consisting of a ball joint, a bowl and a molding. In addition, insofar as a bowl is integral with a fixing disc on a molding, the common bottom of the disc and the bowl is drilled in the center of the bowl, and the disc has a number of radial grooves formed in its face opposite to that equipped with the bowl. This solution also promotes the bonding of a molding on the disc associated with it.

According to another characteristic of the invention, the second branch is mounted articulated at the upper end of the vertical arm by means of a piece in the form of a yoke which the latter comprises, two coaxial holes formed in the central part of the screed and in the rear part of the branch, used for the engagement of a rod blocking the second branch in a determined angular position.

In addition, the second branch comprises, at its front end, that is to say at its end opposite to its articulation axis, a through hole perpendicular to the plane of the branch and into which a pressure screw opens, this hole for the passage of a rod capable of ensuring the maintenance in the high position of the second branch, or of a rod carrying a fork of a facial arc.

This arrangement is interesting to take into account the inclination of the occlusion plane relative to the Frankfurt plane. The second branch can be considered to correspond to the Frankfurt plan.

This second branch is locked in an angular position determined by engagement of the rod in the coaxial holes made in the central part of the yoke and in the rear part of this branch. In the through hole provided at the front end is engaged a rod which carries a fork, the position of which has been determined by means of a facial arc. The inclination of this range gives the inclination of the occlusion plane with respect to the Frankfurt plane.

In any case, the invention will be clearly understood with the aid of the following description, with reference to the appended schematic drawing representing, by way of nonlimiting example, an embodiment of this articulator:

Figures 1 and 2 are two perspective views respectively during the mounting of the impression of a jaw; Figures 3 and 4 are two side views respectively at the end of mounting the molding of a jaw and during the mounting of the molding of a mandible;

Figure 5 is an exploded perspective view of a bowl and a ball joint for mounting a molding; Figure 6 is a view showing the method of fixing a ball inside a branch of the articulator.

The articulator according to the invention comprises a horizontal base equipped with a first branch 2 resting on a support by feet 1. At the rear end of branch 2 is mounted a vertical arm in two parts 3a and 3b, that 3a being integral with branch 2, and that 3b, being slidably mounted in part 3a, is biocable in the desired position using a screw actuated by a lever 4. At the upper end of the part 3b of the arm is disposed a horizontal yoke 5, the opening of which faces forward, at the end branches of which is articulated around a horizontal axis 6, a second branch 7 extending parallel to the first branch 2. There are provided, between the second branch 7 and the hinge axis 6, devices for simulate certain movements of the jaw, which are not described since they are not part of the invention.

The second branch 7 comprises, at its front end, that is to say at its end opposite to the articulation axis 6, a through hole 8 perpendicular to the plane of the branch, and into which opens a pressure screw 9. This hole is used for the passage of a rod 10, capable of ensuring the holding in the high position of the second branch 7, or of carrying the fork 12 with a facial arc. The lower end of the rod 10 is intended to bear on a plate 13 mounted on the first branch 2. It is also provided, to ensure the maintenance of the second branch 7 in a horizontal position, coaxial holes 14 and 15 respectively, formed in the central part of the piece in the form of a yoke, and in the rear end of the second branch 7. A rod, such as the rod 10, engaged in these two holes ensures, as shown in Figure 4, the maintenance of the second branch 7 in a horizontal position, independently of the support which can be provided to the front end of the second branch by the rod 10.

In each of the two branches 2, 7 is formed an opening 16 of triangular section, into which opens a pressure screw 17. This opening is of equilateral section, and the screw 17 opens in the middle of one of the bases, and is oriented towards the vertex opposite this base. Inside each opening 16 is intended to be engaged and blocked, by means of the pressure screw 17, a rod 18 which can be fitted with a support in the form of a plate 19, as shown in FIGS. 1 and 2, or bearing an element 20 in the form of a substantially hemispherical ball joint.

The moldings 22 of the maxilla and 23 of the mandible are each mounted on a support constituted by a disc 24 secured to a cup 25 having a hemispherical cavity complementary to that of a ball joint 20. In the cup 25 are grooves 26 which extend from the edge of the bowl to the bottom thereof, which has a central opening 27. On the underside of the disc 24 are formed a plurality of radial grooves 28. The molds 22 and 23 are fixed. , for each molding, by means of a ball joint and a 24-cup disc assembly 25, with the possibility of adjustment by tilting the cup 25 with respect to the associated ball joint 20, and locking in the position desired by bonding.

The implementation of this articulator is as follows.

First of all, a facial arc is used to measure the angle of the occlusion plane with the Frankfurt plane. To this end, a fork 12 is used which is associated with a rod 10. The facial arch not shown in the drawing comprises a main part situated in a plane corresponding to the plane of the second branch 7, plane from which s extends the rod 10, which carries the fork 12, which will tilt as a function of the inclination of the occlusion plane of the patient. The rod 10 and the fork 12 being removed from the facebow, are transferred to the second branch 7 with locking by the pressure screw 9. The assembly can be supported by a support 19, integral with a rod 18 of section triangular, itself fixed on the first branch 2. The molding 22 of the jaw is placed on the fork, after which a ball joint 20 is placed on the second branch 7, and a disc assembly 24-bowl 25, the disc 24 resting on the flat face of the molding. The molding being thus oriented, thanks to the fork 12, by forming with respect to the second branch 7 an angle which corresponds to the angle of the occlusion plane with the Frankfurt plane, it is proceeded to the fixing of the ball joint 20, cup 25 and disc 24, and molding 22 using glue. The migration of the adhesive is facilitated by the grooves 26, 28. Since it is a quick-setting adhesive, the fixing is carried out in a few seconds. The assembly is then in the position shown in Figure 3. It is proceeded, after opening the articulator, to disassembly of the support 19, of the fork 12, after which the rod 10 is removed from the hole 8, and engaged in the holes 14 and 15 formed at the rear of the articulator to maintain the second branch 7 in a horizontal position. A ball joint 20 is mounted on the first branch 2, in the triangular opening 16 thereof, after which the molding 23 of the mandible is positioned on a disc 24-cup assembly 25. After placing the molding 23 of the mandible in coincidence with that 22 of the maxilla, in particular by adjusting the height by sliding parts 3a and 3b of the vertical arm, the lower ball joint 20 is fixed in this position , of the bowl 25 and of the disc 24 associated with the molding 23. It is possible in this position to check the occlusion of the jaw, to cause the latter to carry out certain lateral movements or relative movements forward and backward, and thus making total or partial prostheses in excellent conditions. It should be noted that the fixing time of the assembly of the two moldings 22 and 23 is a few minutes, and is done with absolute precision, since there are no mechanical tightening means that risk modifying the correct positioning, or risk of expansion on drying, as is the case with plaster. In addition, the fixing operation is carried out very cleanly, which can allow its implementation in dental offices.

As it goes without saying, the invention is not limited to the sole embodiment of this dental articulator, described above by way of example, on the contrary it embraces all variants. Thus in particular that the means for fixing the ball joints 20 on the branches 2 and 7 could be different, or even that the positions of the ball joint and cup could be reversed, the bowls being integral with the branches 2 and 7, and the ball joints being integral with the moldings 22 and 23, without thereby departing from the scope of the invention.

Claims

1. Dental articulator, of the type comprising a horizontal base equipped with a first branch intended to be used for mounting a molding of a mandible, a substantially vertical arm fixed to one of the ends of the base, to the upper end which is hinged, around a horizontal axis, a second branch intended to be used for mounting a jaw molding, each branch (2, 7) comprising fixing means, on its face facing the other branch, d '' a ball joint (20) of substantially hemispherical shape or a cup (25) of complementary shape, while each molding (22, 23) intended to be fixed on a branch is associated with a disc (24) respectively equipped with a bowl (25) or a ball joint (20), depending on whether the branch (2, 7) is equipped with a ball joint (20) or a bowl (25), characterized in that the set consisting of a ball joint (20), a bowl (25) and a molding (22, 2c ant secured by bonding after position molding, and in this vertical arm (3a, 3b) on which is articulated the second branch .ant telescopic, and biocable in the desired position.

2. Dental articulator according to claim 1, characterized in that the fixing means (16) of the two moldings on the two branches are offset from one another, in a direction longitudinal to the two branches, those associated with the first branch (2) being closer to the vertical arm than those associated with the second branch (7).

3. Dental articulator according to claim 2, characterized in that the longitudinal offset of the fixing means of the two moldings is of the order of 15 to 20 mm.

4. Dental articulator according to any one of claims 1 to 3, characterized in that the means for fixing on each branch (2, 7) of a bowl (25) or of a ball joint (20) consist of a rod (18) of triangular section secured to the bowl (25) or the ball joint (20) considered and by an opening (16) of the same section formed in the branch considered, perpendicular to the branch, that is to say substantially vertically, into which opens transversely a pressure screw (17) oriented along a height of the opening in the direction of one of the vertices.

5. Dental articulator according to any one of claims 1 to 4, characterized in that each bowl (25) has grooves (26) formed on its inner face and connecting its bottom to its peripheral edge.

6. Dental articulator according to claim 5, characterized in that insofar as a bowl (25) is integral with a disc (24) for fixing on a molding, the common bottom of the disc and of the bowl is pierced (27 ) in the center of the bowl, and the disc (24) has a number of radial grooves (28) formed in its face opposite to that equipped with the bowl.

7. Dental articulator according to any one of claims 1 to 6, characterized in that the second branch (7) is articulated at the upper end of the vertical arm (3b) by means of a part (5) in the form of a yoke which the latter comprises, two coaxial holes (14, 15) formed in the central part of the yoke and in the rear part of the branch, serving to engage a rod (10) blocking the second branch (7) in a determined angular position.

8. Dental articulator according to claim 7, characterized in that the second branch (7) comprises, at its front end, that is to say at its end opposite to its axis of articulation, a through hole (8) perpendicular to the plane of the branch and into which opens a pressure screw (9), this hole serving for the passage of a rod (10) capable of ensuring the maintenance in the high position of the second branch (7), or a rod carrying a fork of a facial bow.