WO2009141798A2

WO2009141798A2 - Analysis method of the mandibular motor function

Info

Publication number: WO2009141798A2
Application number: PCT/IB2009/052136
Authority: WO
Inventors: Silvestro Roatta; Marco Testa; Mara Rolando
Original assignee: Universita' Degli Studi Di Torino
Priority date: 2008-05-21
Filing date: 2009-05-21
Publication date: 2009-11-26
Also published as: WO2009141798A3; ITTO20080379A1

Abstract

A method comprising the operations of acquiring first and second signals representative of a mandibular movement, representing such signals on a predetermined reference Cartesian plane (XY), respectively on an axis X and an axis Y, through a first plurality of points (110), and individuating a second plurality of points (52), each having predetermined coordinate values, in the first plurality of points (110). The method further comprises the interpolating operations of the second plurality of points (52), creating a closed curve, randomly generating a third plurality of points (54), each having predetermined coordinate values, and representing the third plurality of points on the reference Cartesian plane (XY). Finally, the method according to the invention comprises the acquiring operations of at least one third signal representative of a mandibular movement and representing it on the reference Cartesian plane (XY) through a mobile point (108), the mobile point (108) reproducing the trend of the third signal on the Cartesian plane (XY).

Description

Analysis method of the mandibular motor function

The present invention relates to a method for the analysis of the mandibular motor function as defined in the preamble of claim 1.

To date, physiotherapy is widely used to treat subjects suffering from temporomandibular joint disorders. These disorders are characterized by an altered mobility and pain of the joint and related tissues. Particularly, pain affects the ability of the muscles to exert force and to perform a correct control of the mandibular movement. Such alteration not only acts at the peripheral level, but also involves higher centres, which adapt to the dysfunctional condition by implementing compensation mechanisms which, in turn, are often pathogenetic. A correct behaviour therapy, characterized by a training program which the patient can perform also at his/her own home, and which brings into play the programming and control of the movement, is to be considered as a fundamental and indispensable moment for an efficient intervention in the musculoskeletal disorders such as the temporomandibular disorder. In the latter case, to date this approach is used only in few clinical settings, and the relative literature is still very scarce.

At the moment, automatic methods for the rehabilitation and the objective assessment of the motor functions of the mandible in patients suffering from TDM are not known.

There are apparatuses providing information about the electric activity of the superficial masticatory muscles, such as the electromyographs, and about the mandibular movement, such as the kinesiographs; however, such instruments are not capable of providing objective and reliable information about the articular-muscular performances of the temporomandibular region and the efficiency of the voluntary control of the mandibular movement.

Therefore, object of the present invention is to propose an automatic method for the objective and quantitative assessment of the mandibular motor control.

This and other objects are achieved by a method for the analysis of the mandibular motor function whose characteristics are defined in claim 1. Particular embodiments are the subject of the dependent claims, whose content is to be understood as integral or integrating part of the present description.

Further object of the invention is represented by a system for the analysis of the mandibular motor function and a program for processor as claimed.

Further characteristics and advantages of the invention will result from the following detailed description, provided merely by way of non-limiting example, with reference to the annexed drawings, in which:

- Fig. 1 is a flow chart of the operations performed by the method according to the invention;

- Fig. 2 is a schematic representation of a system adapted to implement the method according to the invention; and

- Fig. 3 is a representation of a mask generated by the method according to the invention.

The method according to the invention is arranged to be performed by a system adapted to process groups or modules of programs stored on a disk or accessible on the Internet.

In Fig. 1 is illustrated a flow chart of the operations performed by the method according to the invention.

The method comprises a first step 1 of acquisition of the mandibular movements as described below, with reference to Fig. 2.

A patient is made to sit on a chair provided with a head support, and he/she is made to wear a kinesiograph 100, for example the Myotronics model K7, which measures the displacement of a magnet 101, which is glued to a reference lower incisor tooth, relative to an antenna 102 secured to the kinesiograph 100 and integral to the patient's head. Then, the kinesiograph 100 measures the head-reference incisor tooth relative displacement, and provides the three -vertical, anteroposterior, latero-lateral- coordinates for this movement in the form of three analogical signals. Alternatively, force transducers are used, particularly two of them, such as, for example load cells, which are arranged on the lower premolar teeth, respectively the right and the left ones. Said transducers are adapted to provide signals representative of the force exerted between the lower teeth and the corresponding upper teeth when the maxilla and the mandible are compressed.

The signals are acquired by an electronic processor 104, provided with an acquisition card 105, which processes them so as to provide in output on a screen 106 images representative of mandibular movements or levels of force developed.

Returning to Fig. 1, the step 1 comprises the acquisition by the processor 104 of signals representative of coordinates of the maximum mandibular movement in a front plane, represented on the screen 106 in the form of a reference Cartesian plane XY, having its origin in a position corresponding to the position of said reference incisor tooth when the patient's mouth is closed (centric occlusion position).

Particularly, the right-left displacements (laterality movements) and the top-down displacements (opening-closure movements) are acquired, reported on the axes X and Y, respectively, of said reference Cartesian plane. In this manner, a projection of the mandibular movement on the front plane is obtained.

Alternatively, it is possible to acquire the back-and-forth displacements (anteroposteriority movements), which are reported on the axis X, in combination with the opening-closure movements reported on the axis Y, thereby obtaining a projection of the mandibular movement on the sagittal plane.

Alternatively, it is possible to represent the laterality movements on the axis X and the an- terposteriority movements on the axis Y, thereby obtaining a projection of the mandibular movement on the horizontal plane.

Alternatively, it is possible to acquire the two signals coming from the force transducers and to bring them on the axis X and the axis Y, respectively, thereby obtaining a represen- tation on a horizontal plane of the level of force exerted between the maxilla and the mandible.

The processor 104 uses said coordinates X and Y to define the position of a cursor 108 on the screen 106: the cursor movement reflects in real time the mandible movement.

The physiological range of motion (ROM) of the mandible on the frontal, sagittal or horizontal plane is called mask. An example of a mask 50 according to the invention is illustrated in Fig. 3.

In step 2, the processor 104 processes the movements acquired in step 1, and creates said mask 50, as described herein below.

The subject is asked to perform his/her maximum mandibular movements: starting from the closure position (centric occlusion), to bring, while gritting teeth, the mandible to the right, then, while holding it at the right side, to bring it to the maximum opening position. Proceed by closing the mandible again, while holding it at the left side, to finally go back to the starting point, while gritting teeth. The cycle is repeated for a preset number of times, for example 4, and the processor 104, by acquiring the signals coming from the kinesiograph 102, reproduces a plurality of curves 110 on the screen 106, each curve 1 10 corresponding to the path performed by the mandible in one cycle.

Alternatively, the subject is asked to compress the maxilla against the mandible first at the right end, then at the left end. The cycle is repeated for a preset number of times, for example 4, and the processor 104, by acquiring the signals coming from the force transducers, reproduces a plurality of points on the screen 106.

The processor 104 extrapolates from said plurality of curves 1 10 a plurality of reference points having either the value of the coordinate X or the value of the coordinate Y, respectively, higher than respective uppermost threshold XTH_I and uppermost threshold YTHI values, or lower than respective lowermost threshold X_JH2 and lowermost threshold YTH2 values. Fours points 52 are illustrated in Fig. 3, which are an example of said plurality of ref- erence points.

Alternatively, the processor 104 acquires only said plurality of reference points 52, instead of acquiring said plurality of curves 1 10.

The processor 104 interpolates said plurality of reference points 52 with a closed curve, thereby obtaining the mask 50. Said mask 50 is stored in a memory 112 of the processor 104 (see Fig. 2).

Alternatively, the mask 50 coincides with one of said plurality of curves 1 10.

In step 4 (see Fig. 1), the processor 104 randomly generates at least one target point 54 (see Fig. 3), having a preset position.

Said target point 54 is generated within a portion 56 of the screen 106 identified by the mask 50. Alternatively, said target point 54 is generated externally relative to said portion 56.

The patient, during displaying of the target point 54, must try to move his/her mandible so as to reach it with the cursor 108 and to keep the position for a predetermined holding time interval T, for example 10 seconds, having at least one first initial sub-interval Q and a second final sub-interval R.

Alternatively, the patient has to compress the maxilla against the mandible so as to reach the target point 54.

In step 6, the processor 104 calculates an instantaneous positioning error as a difference between an initial position of the maxilla (identified by the cursor 108 position on the screen 106) and the position of the target point 54 (target-cursor distance).

In step 8, the rapidity to react and reach the target point 54 is calculated as the reaching time interval elapsed from when the target point 54 appears on the screen 106 until it is reached by the cursor 108. The target point 54 is considered as reached when the cursor 108 coordinates are contained within a neighbourhood of the target point having a predetermined radius, for example lmm.

In step 10, the processor 104 calculates a reaching error as the integral of the target point 54 - cursor 108 distance divided by said reaching time interval.

Alternatively, such reaching error is calculated as the quadratic mean error.

In step 12, a holding error is calculated as the average of the distances between the target point 54 and the cursor 108, measured during the second final sub-interval R.

Advantageously, the positioning, reaching and holding errors are normalized, in a per se known manner, relative to a dimension of the mask, calculated as the area contained within the closed curve representing the mask 50.

Alternatively, a plurality of target points 54 is generated in step 4, having a predetermined probability distribution, for example uniform random. Said target points 54 are sequentially displayed on the screen 106, each remaining on the screen for a predetermined time, for example 10 seconds.

It shall be apparent that, the principle of the invention remaining the same, the embodiments and the implementation details can be varied considerably relative from what has been described and illustrated purely by way of non-limiting example, without thereby departing from the protection scope of the present invention as defined by the annexed claims.

Claims

1. Analytical method of the mandibular motor function, comprising the operations of:

- acquiring first and second signals representative of a mandibular movement;

- representing said first and second signals on a predetermined reference Cartesian plane (XY), respectively on an axis X and an axis Y of said reference system (XY), through a first plurality of points (1 10);

- identifying a second plurality of points (52) in said first plurality of points (110), each having predetermined coordinate values;

- interpolating said second plurality of points (52) to thereby create a closed curve;

- randomly generating a third plurality of points (54), each having predetermined coordinate values;

- representing said third plurality of points on said reference Cartesian plane (XY);

- acquiring at least one third signal representative of a mandibular movement;

- representing said third signal on said reference Cartesian plane (XY) through a mobile point (108), said mobile point (108) reproducing the trend of said third signal on said Cartesian plane (XY).

2. The method according to claim 1 , further comprising the step of calculating an instantaneous positioning error as the difference between an initial position of said mobile point (108) and the position of at least one point of said third plurality of points (54).

3. The method according to claim 1 or 2, further comprising the step of calculating a reaction rapidity as the reaching time interval elapsed from when at least one point of said third plurality of points (54) is represented on the reference Cartesian plane (XY) until it is reached by said mobile point (108).

4. The method according to claim 3, further comprising the step of calculating a reaching error as the integral of the distance between at least one point of said third plurality of points (54) and the mobile point (108) divided by said reaching time interval.

5. The method according to claim 3, further comprising the step of calculating a reaching error as the quadratic mean error of the distance between at least one point of said third plurality of points (54) and the mobile point (108).

6. The method according to any one of the preceding claims, wherein said first and second signals representative of a mandibular movement comprise a laterality signal and an opening-closure signal, respectively, relative to said mandibular movement.

7. The method according to any one of the claims 1 to 6, wherein said first and second signals representative of a mandibular movement comprise an anteroposteriority signal and an opening-closure signal, respectively, relative to said mandibular movement.

8. The method according to any one of the claims 1 to 6, wherein said first and second signals representative of a mandibular movement comprise a laterality signal and an anteroposteriority signal, respectively, relative to said mandibular movement.

9. The method according to any one of the claims 1 to 6, wherein said first and second signals representative of a mandibular movement comprise two force signals, respectively, representative of the level of force exerted between the maxilla and the mandible.

10. An analytical system of the mandibular motor function, adapted to implement the method as claimed in any one of the claims 1 to 10.

1 1. A processing program or group of programs, runnable by a processing system, comprising one or more code modules for the implementation of a method for the analysis of the mandibular motor function according to any one of the claims 1 to 10.