Abstract
The object of the present study was to establish a method of numerical expression for radiographic findings. It was attempted to digitize the shape of the lesions in the radiographs of two oral diseases, dentigerous cysts and ameloblastomas. The lesion of the dentigerous cyst is radiographically characterized by a unilocular and smooth margin and, in contrast, the lesion of the ameloblastoma by a multilocular and scalloping margin. The outlines of the lesions in the pantomograms were digitaized by an image analyzer using the opening method and expressed by the particle indices. The following results were obtained. First, the particle indices of the typical cases of dentigerous cysts ranged from 0.0 to 0.3. Second, the indices of the typical cases of ameloblastoma ranged from 1.0 to 4.0. Third, the indices ranged from 0.0 to 0.3 for the cases of ameloblastoma of which radiographs show oval-shaped or circular lesions. Thus, a correlation was satisfactory between the particle indices and the radiographic findings of the lesions. The results suggest that the particle index is clinically useful as a numerical expression of the shape of the lesion in the radiograph.
