Radiographic examination of the mandibular (glenoid) fossa in ancient and modern man

OBJECTIVE: To compare the morphology of the mandibular (glenoid) fossa between ancient and modern Japanese. METHODS: There were 221 specimens from the ancient period and 206 specimens from the modern period. Radiographs of the mandibular fossa were obtained using a modified Schuller technique and were studied. The length, depth, and area of the mandibular fossa and angulation of the frontal slope of the mandibular fossa on the radiographs were automatically computed. In addition, morphological changes of the mandibular fossa in the ancient or modern periods on radiographs were evaluated in order to assess tendency of temporomandibular joint disorder (TMD). RESULT: The ratio of mandibular fossa having morphological alternation in the modern period was greater than that in the Yayoi. Differences in the length and area between the right and left sides became progressively larger from the Yayoi to modern periods. The angulation of the anterior slope of the mandibular fossa in the modern period was smaller than that in other periods. CONCLUSION: The morphology of the mandibular fossa was shown to have changed and asymmetry has increased from the Yayoi to modern periods. It can be speculated that this change in morphology of the mandibular fossa in the modern period is the result of an increase of TMD.