Radiologic diagnosis of enostosis in the mandible

Abstract

Enostosis occurs from the inner surface of cordal bone and grows into the cancellous bone. This lesion has not been understood in detail. Three-dimensional images by cone-beam CT for dental use can be useful to diagnose this lesion. Although osteosclerosis, focal condensing osteomyelitis, and dysplastic lesions of the jaw bone occur near the root of tooth, their shape and aspect observed on rotational panoramic radiographs are often similar to enostosis. Therefore we attempted to differentiate these lesions from enostosis using radiographic features. Enostosis is usually not extracted; therefore the diagnosis of enostosis is actually done by cone-beam CT for dental use (3DX multi-image microCT; Morita, Kiyoto, Japan), which can precisely observe the relationship between the lesion and adjacent cortical bone. Forty radiopaque lesions diagnosed as enostosis from their radiographic features by 3DX images were used in the study. The radiographic features of these 40 lesions were investigated using panoramic, periapical and occlusal radiographs. The appearance of 40 lesions was observed according to occurrence site, relationship with the roots of teeth by these radiographs, relationship with the mandibular canal, and the shape of lesions by 3DX images. Fifty percent of the cases of enostosis were located in the premolar region in the mandible and observed osteosclerosis-like images surrounding the mental foramen or mandibular canal on 3DX images. Twelve cases of enostosis arose from buccal cortical bone, 23 from lingual cortical bone, and 5 unclassified. On the rotational panoramic radiographs, 40% of the enostosis masses made contact with tooth roots, 40% were located in the body of the mandible, and the remainder were edentulous. The enostosis presented as an ovoid radiopaque lesion on the rotational panoramic radiographs, and their internal structure showed either uniform radiopacity or not. Lamina dura of adjacent teeth nearby the lesion showed clearly. Neither rotational panoramic radiograph nor occlusal radiograph can exactly diagnose the location and state of the enostosis. 3DX images can diagnose this lesion in detail.