The said articulators normally comprise two parts one of which can move with respect to the other and which can be attached to the upper and lower arches respectively of the dental prostheses which it is intended to construct.

By making these attachments, and then keeping one of the parts fixed while moving the other in such a way as to simulate the relative motion between the two arches attached to them caused by chewing movement, a dental technician can adjust the position and shape of the crown of teeth which is to form a prosthesis.

In articulators according to the present state of the art, both in those cases where the part attached to the lower dental arch is fixed and the other is moved with respect to it, as e. g. in patent application DE 4 330 297 Al or patent US-A-4,886,453, and in the case where the opposite operation is performed, that is keeping the part attached to the upper dental arch fixed, such as e. g. in patent US-A-5,586,884 and European patent application 84810444.4, the relative motion between the two parts of the articulator, and as a consequence between the dental arches of a prosthesis, is brought about only by means of several translational movements performed in vertical or horizontal planes.

Even if these translational movements are compounded together, and all known systems for regulating and recording the said translational movements are used at the same time, it is never possible, for obvious geometrical and anatomical reasons, to achieve a

satisfactory simulation of the chewing movement which the teeth in the prosthesis will actually perform in a patient's mouth cavity. ~ This is due to the fact that a mandible moves in three planes in space, that is in the horizontal, sagittal and transverse planes, as it performs composite translational/rotational movements of its condyles in the cavities of their corresponding joints, cavities which also contain a deformable meniscus which further governs the resulting motion of the condyle as the compression upon it, and therefore the movement of the mandible, varies.

After having worked for years in the field of dental technology, and having discovered the existence of the limitations and inconveniences mentioned in articulators of the known type, the inventor of this invention has conceived one in which the two said upper and lower parts which comprise it are attached together by means of one spherical joint.

This conformation, together with other significant arrangements which will be described below, make it possible to prepare prostheses in which the relative positions between opposing and/or adjacent teeth are already optimally defined at the time when the prosthesis is constructed, and which therefore do not require performance of the long and time-consuming work of adjustment which up to now has had to be performed in order to make a prosthesis usable without the occurrence of impacts or interference between the apical portions of the teeth in the two opposing arches.

The subject matter of this invention in fact comprises an articulator as described in the precharacterizing clause of attached claim 1, characterized by the characterizing clause of the same claim.

A description of a preferred embodiment of an articulator according to the invention, in which the characteristics and advantages achieved with it are more particularly pointed out, will now be provided.

In the course of the above description, reference will also be made to the appended figure, which shows a side view of the said embodiment of the articulator according to the invention.

If the abovementioned figure is considered, it will be seen from it that articulator 1 according to the invention comprises an upper fixed part and a lower moving part represented by two U-shaped arms 2,3 connected together with the open parts opposite and facing each other.

To ease interpretation of the drawing, the letters H, G, E, D are associated with U-shaped arm 2 mounted above, and letters O, N, M, L refer to uniform-shaped arm 3 mounted beneath.

These arms 2,3 are attached together by means of a spherical joint 7 comprising an essentially spherical head 8 which is attached to one of them housed in a substantially hemispherical matching cavity 9 provided in the other.

In the example illustrated, said head 8 is attached to lower arm 3 and said substantially hemispherical matching cavity 9 is provided in upper arm 2, but a reverse arrangement of the parts (not shown) may also be constructed by means of technical arrangements which are well known to those skilled in the branch of mechanics.

Spherical head 8 is kept in contact with cavity 9 of matching shape by means of a metal blade 13 acting as a bracket with the projecting part pressing against it downwards.

This arrangement is preferred in that, while keeping the parts stably in contact with each other, it guarantees full adjustment of the joint to a great variety of kinematic situations with some elasticity, but other arrangements may also be adopted without incurring any special difficulty.

The two dental arches 4,5 of a dental prosthesis 6 are attached at the two opposite ends O, H, of arms 3,2 respectively so that they can approach each other simulating the configuration adopted during chewing.

Lower U-shaped arm 3 has its sides connected together so that they can rotate with respect to each other in <BR> <BR> <BR> order to reproduce precisely the angle a of the mandible found in the patient.

As will be seen in the figure, horizontal side MN of lower arm 3 is hinged on the end of vertical arm LM, and its position is fixed by known means (e. g. using fixing bolts or clamps) when the desired aperture of angle a has been achieved by screwing up or unscrewing a threaded contact point 15 which presses against the underside of said side MN of arm 3, opposed by the tensile force applied by an opposing spring 14.

Of course devices for the micrometric recording of all the sides of the two arms 2,3 may be applied and used in accordance with known methods. A further arrangement provided by the inventor consists of the fact that the horizontal side GE of upper fixed arm 2 comprises two segments 2m, 2p which are hinged together in such a way that one can rotate with respect to the other about a vertical plane.

Their position can then be fixed even only by the mere friction generated in hinge 2n through the effect of the action of springs or mechanical equivalents (not shown in the figure).

With the arrangement of the various parts of an articulator according to the invention described here it is possible to adapt the geometry of the various component parts of a dental prosthesis in a perfectly ergonomic way, thus avoiding the patient long and irksome periods of physical discomfort.

With the object of having a graphical record which illustrates the movement between the two dental arches 4,5 during their relative motion performed in the course of chewing, the inventor has made provision for fitting a pen 10 to lower moving arm 3 of articulator 1 which is dimensioned and positioned in such a way as to trace a line which reproduces the trajectory of its relative movement with respect to fixed arm 2 when said arm 3 is moved in a transverse direction, a trajectory which is defined by the relative gliding of the opposing teeth of the prosthesis which are in contact with each other.

Once the course of the typical lines for the various possible modes of chewing have been established experimentally, it is easy to see from the lines drawn by pen 10 whether or not there are individual points of interference between the teeth or irregularities in the contact between them, identifying the position of these precisely and accurately.

It is then possible to act immediately and precisely on the cause of the said disadvantages, ensuring an ergonomic positioning and modelling of the opposing and/or adjacent teeth in the prosthesis on which one is working.

Said pen 10 is attached to lower arm 3 by means of an interposed flexible and elastic member, such as e. g. a steel blade 12 in the situation illustrated, so as to guarantee continuous contact between point 10 and horizontal surface 11 on which it traces the said lines even when there is relative vertical movement between

the two arms 2,3 as a result of sliding between the apical points of the crowns of the teeth in the two arches 4,5 of prosthesis 6.

In the case in point, the said horizontal surface is a plate 11 attached to the plane supporting articulator 1.

It is obvious that a variety of embodiments of an articulator according to the invention which differ from that described hitherto by way of example can be obtained.

The shape, method of attachment and relative positioning between the various parts which make it up can in fact be modified by a designer in accordance with design requirements.

Embodiments of an articulator so obtained, but always inspired by the teaching contained in the attached claim 1, nevertheless fall within the scope of the protection conferred by this patent application.