1993 Volume 5 Issue 1 Pages 48-61
The aim of this study was to clarify the portion forming the contour of the mandibular head by temporomandibular joint (TMJ) frontal projection, and to clarify whether the shape of the mandibular head by TMJ frontal projection conformed to that by Yale's classification.
The projections evaluated in the present study were Grant-Lanting, modified Grant-Lanting, Clementschitsch, transmaxillary, Takaku, and Zimmer projections.
Lateral roentgenographic cephalography at maximal opening of the mouth was performed in the following two groups: 20 healthy volunteers with an inter-incisal opening more than 40mm, and 20 patients of cranio-mandibular disorders with an inter-incisal opening less than 35mm. The mean vertical angulation identical to the central X-ray beam of each TMJ frontal projection against the mandibular occlusal plane was obtained from those cephalograms.
The tangential point of the central X-ray beam in each TMJ frontal projection to the contour of the mandibular head was examined as the portion forming outline of the mandibular head in the lateral view of 58 mandibular heads of human dry skulls.
The shape of the mandibular head by TMJ frontal projection and that by Yale's classification were compared by using photographs of the same human dry skulls.
The results of the study were as follows:
1) The portion forming the contour of the mandibular head by frontal projection was within the posterior surface of the mandibular head, and the lower portion of the posterior surface was depicted as the mouth opened more widely.
2) The condylar contour by frontal projection showed the outline of the posterior surface of the mandibular head, and did not conform to the shape of the mandibular head by Yale's classification.
