Comparative examination of the localization of the terminal hinge axis

The following paper shows the identification of the terminal hinge axis using two different electronic axiography systems. The terminal hinge axis points were determined and compared in 26 subjects (5 male, 21 female, average age 38 ± 10.8 years) who had been selected from a patient population receiving occlusal splint therapy. This was done using a juxta-articular hinge axis tracing appliance (CADIAX® diagnostic) and an abarticular tracing appliance (Jaw Motion Analyzer®). For the statistical evaluation of the consistency between the different methods to determine the terminal hinge axis points, Pearson's correlation coefficient was determined. On average, the mean terminal hinge axis point values of both systems showed a good to very good correlation. The correlation coefficient determined for the respective coordinates indicates an average (x coordinate left: 0.53) to good (y coordinate left: 0.9) correlation of results. The hinge axis points established by the CADIAX diagnostic showed a higher reproducibility than the points determined by the Jaw Motion Analyzer system. The range of dispersion seems to depend upon the scale of the translational movement and upon the ability to control translational movements in hinge axis movement. The CADIAX diagnostic provides such rotation control during dynamic axis localization. The Jaw Motion Analyzer should have this type of control system added. Not all temporomandibular joints are able to perform translation-free hinge axis movements. Keywords: CADIAX diagnostic, hinge axis movements, Jaw Motion Analyzer, terminal hinge axis