[Validation of the technique of TMJ 3D analysis based on computer tomography]

The main aim of the study is devoted to optimization of the technique of 3D analysis of TMJ parameters, analysis of the causes of possible errors.

The technique of 3D analysis of the width of the articular gap, the size of the condyle, the height and slope of the distal slope of the articular tubercle in the Avantis3D software (Russia) according to computed tomography is presented. The influence of repeated manual corrections of the condyles and articular fossa contours, shifting of the sectors measuring center, the position of starting point of the measurement sectors, and different algorithms for determining the longitudinal axis of the condyles on the accuracy of TMJ parameters detection.

The study showed that any artificial displacement of the center of measurement sectors, which coincides with the longitudinal axis of the condyle, leads to significant value changes of the parameters. In this regard, the exact determination of the longitudinal axis of the condyles, independent of the human factor, is of particular importance. The greatest inaccuracy and variability of the results of measuring the parameters of the TMJ, as shown by the study, is associated with the possible manual correction of the contours of the surfaces of the condyles and articular fossa. The study did not find a noticeable difference in measurements if the sectors starts from the top of the articular tubercle or from the line parallel to the Frankfurt horizontal. As the optimal settings of the developed method was determined, it was used to determine the average values of the TMJ parameters for patients with a conventional «norm», as well as for patients with TMJ dysfunction. A noticeable and statistically significant difference was found between the groups only for upper and posterior width of the joint space.

The average values of the intra-articular spaces width were justified, and can be used as the basis for the virtual assignment of the lower jaw reconstructive position for prosthetic or orthodontic treatment.