Limits of perceptibility of condyle displacements on temporomandibular joint radiographs.

The present study investigated to what extent condyle positions have to be different from each other in order to be clearly detectable under clinical conditions on serial radiographs of the temporomandibular joints in identical projection. For that purpose of ten test subjects serial radiographs in optimal lateral oblique and identical projection were made with various positions of the joint. The joint was brought to these positions by displacement of the mandible to an exactly known extent with a special device. Evaluation showed that mean differences between condyle positions of 0.61 +/- 0.16 mm can be recognized clearly. It was statistically proved that this value did not depend upon the experience of an examiner in reading radiographs but upon the technical quality and the interpretability of the radiographs as well as upon the radiographic dimension of the posterior joint space.