P. RAMMELSBERG, H.C. MAY, P. POSPIECH, W. GERNET. (Department of Prosthodontics, University of Munich, Germany)
During the last decade numerous attempts were made to use recordings of mandibular movements to improve the accuracy of diagnosis of craniomandibular disorders. The lack of controls, missing calculations of sensitivity and specificity as well as inaccurate golden standards reduced the scientific value of former investigations [MOHL 1990]. Objective of this study was to evaluate the diagnostic value of 3-D computed axiography to detect anterior disk displacements (ADD) of the TMJ. 65 patients with MRI (magnetic resonance imaging) confirmed diagnosis of ADD with reduction and 27 patients with ADD without reduction were examined by 3-D computed axiography. 44 healthy volunteers with normal disk position and joint function served as controls. A descriptive analysis of the axiographic opening/closing cycle revealed significantly higher rates of abrupt deviations, accelerations/ decelerations, and crossings for ADD with reduction compared to healthy volunteers (Wilcoxon U-test p<0.001). However, a considerable number of asymptomatics presenting abnormal axiographic curves, and a high rate of patients without abnormal curves complicated diagnosis based on axiography. A new axiographic index integrating all descriptive criteria, reduced the number of false positive diagnosis to 10% , and the number of false negative diagnosis to 14% . ADD without reduction was characterized by significantly shorter opening curves. The optimum split point at 11 mm, resulted in 10% false positive and 20% false negative diagnosis. However, the diagnostic value of computed axiography was reduced by the significant influence of the clicking or limited joint on the contralateral TMJ. We conclude that unilateral ADD with and without reduction can be detected with an acceptable sensitivity and specificity by use of 3-D computed axiography, if a substantial variability is taken into consideration.