Axiography allows the three-dimensional study of condylar movements in the perspective of diagnosis of cranio-mandibular dysfunctions (CMD) and real adjustment of the semi-adaptable articulator.

Conceived by Cammpion in 1902, Robert Lee was responsible for updating this principle of study.

This technique, according to Cardonnet and Clauzade (1987), must be used as soon as a joint problem is suspected and is one of the means of choice for the differential diagnosis of temporomandibular disorders of articular origin, such as reducible dislocations, irreducible dislocations. Among the proposed methods for the recording of mandibular kinematics, the Lundeen [1,2] axiography developed by Slavicek represents a technically validated methodology for recording condylar displacements [3]. Axialized recording of condylar displacements eliminates the rotational movement to preserve only the translation movements. This recording allows the choice of the condylar slope to program the semi-adaptable articulator.

The comparative study of Frongia between the MRI examination and axiographic plots in the diagnosis of TMJ internal disturbances, did not find any different contradictory result hence it is a very interesting diagnostic tool at the same rank as the MRI examination, the latter is less used in the diagnosis of CMD because of the higher cost and the acquisition of images is in a static position of opening and closing mouth [4].

The prevalence of signs and symptoms of craniomandibular dysfunction is relatively high, the results obtained exceed on average 50% of the general population. The percentages obtained differ according to the studies: according to Bonjardim et al. (2009), 50% of the general population has at least one sign of TMJ disorders, according to Pedroni et al. (2003) cited by Robin et al. (2006), 68% and the prevalence increases to 75% in the study by Nassif et al. (2001).

-The noise or the deviation at the mouth opening represents 30% to 50%.

-The limitation of mouth opening represents only 4% to 10%.

-75% have at least one sign of DAM.

-41% have a muscular DAM.

-33% present an articular DAM.

-Only 7% are sufficiently severe to require treatment.

CMD are of interest to both sexes regardless of age, with female pre-dominance and age range between 15-45 y old [2].

It is a descriptive clinical study carried out on 20 dented and edentulous partial patients whose age is 31 y, selected following the presence of the signs and symptoms of TMJ disorders (noise, algie, dyskinesia), the criteria of inclusion were the absence of prior orthodontic treatment or prosthetic device; all were subjected to a clinical examination completed by a mechanical axiography.

The data were collected through para-condylar flags which were subsequently examined for the equivalent of twenty plots.

The apparatus used is the Quick axis of the Fag firm which consists of a facial bow on its sides of the ear tips that are placed in the external auditory canals of the patient with a frontal bar on which attaches an occlusal splint intended for the lower arch, the latter will be filled with a high polyvinylsiloxane, taking care to position its stem parallel to the medial sagittal plane of the patient. A sagittal arch recording arm on which the record stylus and the tambour are fixed at the right and left paracondylar registration flags.

A facial bow with its nasal support and elasticized back strap

The frontal bar should be parallel to the transverse face of the face bow in the horizontal and frontal plane.

The recording stylus is fixed on the locator arm in contact with the corresponding recording area at the intersection of the two horizontal and frontal axes, thus materializing the arbitrary hinge axis: this is the point ‘0’.

The help of a dental assistant is essential to correctly place the axiograph on the patient; the total duration of this operation is about 10 min.

The patient was subsequently asked to perform opening and closing movements and a propulsion movement from the centred position, having previously interposed articulated paper between the stylus and the paracondylian flag, a plot will be obtained at the end of this phase which will be analyzed later (Figures 1-4).

The value of the condylar slope is calculated once the para-condylar flag has been recovered, it is enough to draw a tangent joining the starting point and the steepest point of the recorded path (the para-condylar flag being numbered from 0° to 70°).

Axiography is a non-invasive para-clinical examination of the mandibular kinematics and more precisely of condylar displacements thus allowing the real programming of the posterior determinants of the semiadaptable articulator.

It was Slavicek [3] who showed interest in studying the pathology of the disc joint. The slope of the tracings relative to the reference axio-orbital plane (franking plane) of our study is between 38° and 70° calculated from the first 5 millimetres of condylar excursion, the angle of Bennett is calculated according to the Hannau formula B=h/8+12. We also noticed that the return movements do not necessarily end at the reference point (hinge axis) (Figures 5-12).

Axiography allows

-Arbitrary localization of the hinge axis.

- Three-dimensional visualization of the recordings.

-Storage tracks.

-Calculating the angle of the condylar trajectory and the angle of Bennett, it is enough to draw a tangent at the most declivitous point of the recording.

-Is the only way available to the practitioner to record mandibular kinematics?

-Descriptive of the different traces obtained.

The criteria for interpreting routes are based on

-Their amplitudes: important, average or reduced.

-Their characteristics: rectilinear concave convex or changeable.

-Reproducibility: partial or total superposition in the same patient

-Their mode: symmetry or not on the right side with the left side and on the same patient.

-The comparison is made between the so-called physiological trace taken into consideration from the beginning of the study and pathological traces obtained.

The physiological trace is very rare and is characterized by

-Easy locating of the real hinge axis, the patient comes back at the end of closing movement,

-The amplitude of the plot is greater than 15 mm/16 mm.

-The plot is concave upwards

-The traces are repetitive and superimpose.

-The movements are harmonious, regular, without stop or jump.

-At the end of the movement the plot is net without loop (Figure 5).

The different pathological patterns

In the case of ligament distension: The line is often split and overloaded with small jerky movements.

Reducible disc dislocation: Different expressions of this articular pathology are visualized by the axiography whence its diagnostic interest, the cracking can be at the beginning, middle or the end of the movement of opening/closing mouth with a click of go and back (the earlier the cracking is, the better the prognosis), the hinge axis is unstable because it is located in the bilaminary zone (Figures 7 and 8).

The irreducible disc dislocation acute: The axiographic examination shows a short rectilinear plot associated with overlays (Figure 10).

Chronic irreducible disc dislocation: The axiographic plot may resemble the physiological pattern, except that the concavity tends to disappear, in this case the value of the angle of the condylar slope tends to decrease (Figure 12).

Once the positive diagnosis is made, a treatment plan is planned to treat the musculo-articular pathology.

The study of the plots obtained (shape, angulations) are consistent with those that exist in the literature, the work of Dupas performed jointly on the mechanical Axiograph Quick axis and SAM [5-13] (Figures 9 and 11).

Despite the absence of an axiographic mapping of condylar trajectories and pending further studies, axiography is of very significant diagnostic importance, indeed, as and when it is used, the practitioner will master its rational use.

The authors do not declare any conflict of interest in relation to this article.