[Hirtz's incidence in the study of the manducatory apparatus. Application to temporomandibular joint affections (author's transl)].

Radiological examinations have always been considered of secondary importance during diagnostic investigations of temporomandibular joint affections because of the frequency with which negative results were obtained. For most authors its only value has been to establish a differential diagnosis from other lesions of the manducatory apparatus in which clinical manifestations are comparable. A systematic study of the manducatory apparatus in patients with temporomandibular joint affections was carried out by taking two films, one with the month open, the other with the month closed, according to Hirtz's incidence. The results showed that abnormalities of varying degrees of severity were present relatively frequently. They usually involved the temporomandibular joint, either morphologically or physiologically. The multiplicity of the abnormalities observed, their character, and their frequency raise the problem of defining their role in the genesis of the disorders described and strongly suggests that the place of radiological investigations in the diagnostic tests for temporomandibular joint affections has to be reconsidered. The examination described would be, because of its simplicity, the basic investigation in the radiological study, with other studies possibly following on later to complement it.