[Alterations in the size, shape and position of the condylar surfaces in the orthopantomograph. In vitro study]

Although the orthopantomograph has some disadvantages comparing with other techniques in the study of the TMJ, is useful sometimes for visualization of extensive osseous changes of the condyles. This study was done in order to study the exact site of the radiographic representation of the condylar surfaces in the orthopantomograph and to evaluate the degree of alteration of their size and shape. In two dry skulls (one edentulous and the other with complete dentition) a lead foil was placed in each one of the five surfaces of the condyles. The orthopantomographs were taken and the site of the radiopaque lead foil was evaluated for the radiographic representation of each surface. Also the degree of the alteration of the size and shape of the condylar surfaces was determined by the calculation of the two dimensions of each surface, in the skull and in the radiograph. The results of this study showed that all five condylar surfaces are contributing for the radiographic image of the condyle and always in an exact position each of them. The greatest distortion of the size and shape is taken place in the upper surface of the condyle and finally that the orthopantomograph cannot give us exact and accurate representation of the shape or the morphology of the condyle.