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Technical field of the invention

The present invention relates to a System for the simulation of mandibular movement .

Prior art

There are known in the art system for the simulation of mandibular movements that provide image capturing means of the mandibular movements of a person (typically one or more video cameras), and markers that are used as reference to accurately display the mandibular movement.

The data thus acquired are then transferred, by means of an appropriate computer, to a robot which is used to mechanically reproduce the mandibular movement acquired through the capturing means . To display the reproduced mandibular movement, the robot is provided with seats for fixing a cast of the jaws of a person. The seat for the upper jaw is usually fixed whereas the seat for the lower jaw is movable so as to reproduce the captured movements.

As a result of the reproduction of the mandibular movements through the robot, it is possible to produce dental devices (prostheses) or the like that are adapted not only to the morphology of a person, but also to the movements of the person's lower jaw. Moreover, the system allows the movement data to be acquired so that the work can then be carried out without further involvement from the person.

A prior art system of this kind is illustrated, for example, in the document EP 0 910 997.

However, prior art systems can be improved in their acquisition accuracy and in the reproduction of the mandibular movements. For example, the system illustrated in EP 0 910 997 comprises a robot in which the cast of the lower jaw is moved by means of a "delta" kinematics, which includes six motors. This mechanism has the disadvantage of involving a non- negligible backlash between the motors and the related axes to be moved. Such backlash on six motors results in an accuracy loss in reproduction of the mandibular movements.

Another improvable aspect of known systems relates to the mechanical part of the robot, which also has an impact on the reproduction accuracy of the mandibular movements.

Brief summary of the invention

Therefore, the object of the present invention is to produce a system for the simulation of mandibular movements that is capable of reproducing the mandibular movements with greater accuracy with respect to known systems.

Within this task, a further object is to produce a system for the simulation of mandibular movements with a simplified mechanical part and suitable to reproduce the mandibular movements with greater precision .

These and other objects are achieved by a system for the simulation of mandibular movements according to claim 1.

The dependent claims define possible advantageous embodiments of the invention.

Brief description of the drawings

For a better understanding of the invention and appreciation of its advantages, some non-limiting examples of embodiment will now be described, with reference to the accompanying figures, wherein:

Fig. 1 is a perspective view of a robot according to a possible embodiment of the invention;

Fig. 2 is a side view of the robot of Fig. 1;

Fig. 3 is a perspective view of another component of the system; and

Fig. 4 is a plan view of the component of Fig. 3. Description of embodiments of the invention

The system for the simulation of mandibular movements according to the invention comprises a robot, suitable to reproduce the mandibular movements of a person, an analysis part, to record and analyse the mandibular movement of a person, and a transfer part to transfer the mandibular movement recorded by the analysis part to the robot.

The analysis part comprises a video camera and at least two markers to apply to the dental arches of the person. These markers, which are preferably two (one for each of the dental arches), are connected to a related bite splint which has been developed from plaster casts of the dental arches of the person.

An example of robot of the system according to the invention is indicated in the accompanying figures with the reference numeral 1. The robot 1 can be of the type indicated in the introduction of the present description.

The robot 1 comprises a first fix base 2 suitable to support a cast of the upper dental arch, and a second fix base 3 designed to support a cast of the lower dental arch (Fig. 1) . Preferably the fix bases 2, 3 are arranged horizontally. The first fix base 2 is arranged above the second fix base 3. The robot 1 further comprises a movement assembly 10 of the fix bases 2, 3, which comprises six motors 11A-C, 12A-C (Figs. 1 and 2). Three motors are travel motors 11A-C, suitable to translate an object along a direction, and the other three motors are rotation motors 12A-C, suitable to rotate an object about an axis .

Advantageously, the first fix base 2 is fixed while the second fix base 3 is movable, so as to best imitate the mandibular movements. Naturally, the movable fix base is connected to the movement assembly 10.

According to the present invention, the three rotation motors 12A-C are arranged so as to form a gyroscopic structure. That is, they are arranged so as to form a gyroscope.

More precisely, the movement assembly 10 comprises a first support 13, a second support 14 and a third support 15. One of the fix bases 2, 3 (advantageously the second, as illustrated in the figures), is fixed on the first support 13; the first support 13 is mounted rotatable on the second support 14 so as to rotate about a first axis Al and is connected to a first rotation motor 12A; the second support 14 is mounted rotatable on the third support 15 so as to rotate about a second axis A2 perpendicular to the first axis Al and is connected to a second rotation motor 12B; and the third support 15 is in turn mounted rotating on a first platform 16 so as to rotate about a third axis A3 perpendicular at least to the second axis A2 and is connected to the third rotation motor 12C.

In the example illustrated, the first support 13 and the third support 15 have a flat body 13A, 15A shaped as an elongated strip, and two connection elements 13B, 15B perpendicular to the flat body 13A, 15A. The second support 14 instead has a body 14A in a shape of a quadrilateral with the sides perpendicular two by two, and provided with four connection panels 14B perpendicular to the plane of the body 14A, each preferably in substantially central positions of each of the sides of the body 14A (Fig. 1) .

The connection elements 13B of the first support 13 are connected rotatable to two connection panels 14B of the second support 14 facing each other, and the connection elements 15B of the third support 15 are connected rotatable to the other two connection panels 14B of the second support 14.

It is understood that the first axis Al and the second rotation axis A2 are always perpendicular to one another, and that the second rotation axis A2 and the third rotation axis A3 are always perpendicular to one another. Preferably, the second rotation axis A2 is horizontal and the third rotation axis A3 is vertical (as illustrated in Fig. 1) .

According to a particularly preferred embodiment, the three rotation axes Al, A2, A3 of the three rotation motors 12A-C intersect at an intersection point. This intersection point can be used as a reference point to reproduce the mandibular movements, as will be better explained below.

Within the context of the present invention, axis of a rotation motor means the axis about which this motor rotates an object, such as one of the supports 13, 14, 15.

The first platform 16 is connected to the three travel motors 11A-11C so as to be movable along three directions, preferably perpendicular to one another, and even more preferably parallel to the three rotation axes Al, A2, A3 of the three rotation motors 12A-C.

More precisely, the first platform 16 is mounted sliding vertically, by means of a specific guide 17, on a second platform 18, which is in turn mounted sliding horizontally and along two directions on a base 19. The guide 17, the second platform 18 and the base 19 are comprised in the movement assembly.

In the example illustrated, the second platform 18 is suitably connected to the first and to the second travel motor 11A, 11B, which are orientated horizontally and perpendicularly with respect to each other, while the first platform 16 is connected to the third travel motor 11C, orientated vertically (Figs . 1 and 2) .

The system for the simulation of mandibular movements further comprises a numerical control suitable to control the robot 1 and to operate the six motors 11A-C, 12A-C to reproduce the recorded mandibular movement . Preferably the numerical control has a program and a computer.

It should be noted that the robot further comprises a support member 30 suitable to support, in a fixed position, one of the fix bases 2, 3. Preferably the support member 30 supports, in a fixed position, the first fix base 2, suitable to support the cast of the upper dental arch.

Figs. 3 and 4 illustrate a structure 20 for developing bite splints with the markers 4A, 4B, which are used to record the mandibular movements of the person, as explained above.

The markers 4A, 4B are at least two, one for each of the dental arches. Given that in the system in question one of the casts is fixed and the other is movable, it is understood that a first marker 4A will be fixed and a second marker 4B will be movable. Preferably, this second movable marker 4B is used as a reference point for analysis, and quantification, of the mandibular movements.

For this purpose, the structure 20 comprises at least a first seat 21, for the movable cast of the dental arch, and a second seat 22, for the second movable marker 4B. Preferably the movable cast of the dental arch is the cast of the lower dental arch. The distance between the centre of the first seat 21 and the centre of the second seat 22 is the same as the distance between the centre of the movable fixing base 2, 3 of the robot 1 and the point in which the three rotation axes Al, A2, A3 of the rotation motors 12A-C of the robot 1 intersect. In this way, this intersection point will be the reference point in the robot to reproduce the recorded mandibular movements.

In the example illustrated in Figs. 3 and 4, the markers 4A, 4B comprise a square shaped flat plate, and are connected to the bite splints through respective arms 5A, 5B.

Preferably the markers 4A, 4B comprise a central protrusion, not represented in the figures, which allows determination both of the distance between the markers 4A, 4B and the video camera that films the mandibular movements, and of the angle of the rotations of the same markers 4A, 4B. For example, the central protrusion can be hemi-spherical . Alternatively, it is possible to provide several protrusions on the markers 4A, 4B.

Advantageously, the structure 20 further comprises a third seat 23 for the first fixed marker 4A, so as to be able to adjust the position in relation to the second marker 4B. The second seat 22 and the third seat 23 can be obtained in a same body 24, as illustrated in Figs. 3 and 4.

Even more preferably, the second seat 22 and the third seat 23 are coplanar, so that when the bite splints are produced the two markers 4A, 4B are also coplanar when the two bite splints touch, i.e., when the person clamps or closes the dental arches.

In this regard, it is advantageous to provide a cover 25 suitable to cover the body 24, and therefore the second seat 22 and the third seat 23, and to maintain the two markers 4A, 4B coplanar (Fig. 3) . In this way, it is possible to provide software for analysis of the mandibular movements that measures the coplanarity of the markers 4A, 4B. Naturally, it is possible to use other types of software for analysis and quantification of the mandibular movements.

A procedure for simulating of the mandibular movements through the system described above will be explained below.

Firstly, a plaster cast is made of the dental arches of a person.

Subsequently, the bite splint is constructed on the structure 20 with the aid of the casts previously produced .

This is followed by a step of recording and analysing the mandibular movements of the person. The person is made to wear the bite splints produced and provided with the markers 4A, 4B as previously described, and the mandibular movements are recorded by means of the video camera. The video, with the mandibular movements, is preferably recorded in a file on a computer. Simultaneously or subsequently, the program for analysis and quantification of the mandibular movements is used.

It should be noted that, according to a preferred embodiment, in this step analysis and quantification of the mandibular movements are performed thanks to the video images and an artificial vision program. An example of procedure for quantifying the distance and the angle of the markers has been previously described .

Finally, by means of the file acquired and the result of the analysis, the robot 1 is controlled to reproduce the mandibular movements recorded in the previous step.

The person skilled in the art may make numerous additions and modifications to the described embodiments of the System for the simulation of mandibular movements according to the invention, or may replace the elements with other functionally equivalent elements, all without departing from the scope of the appended claims .