Clinical and panoramic assessment of marginal bone loss. A cadaver study.

The purpose of this study was to investigate the reliability of panoramic tomography for the assessment of marginal alveolar bone loss. The study was conducted with 20 human cadavers, in relation to 123 of their teeth. Panoramic tomograms of the cadaver dentitions were taken using a Zonarc radiographic apparatus. Root lengths and bone losses were measured mesially and distally from the panoramic tomograms. Bone loss was also measured by surgical exposure of the marginal bone. Root length was also measured after extraction of the tooth. After allowing for the vertical magnification, radiographic bone loss values were found to be about 0.8 mm (27%) less than clinical values. This difference was statistically significant only in the incisor area. It was almost significant in the premolar region. It is therefore concluded that panoramic tomography is sufficiently reliable for clinical assessment of alveolar bone loss but that the bottom of periodontal pockets always tends to be somewhat deeper than the radiographically visible defect.