Measurement of mandibular bone mineral content using the dental panoramic tomogram

The aim of this study was to determine whether bone mineral content could be estimated densitometrically using dental panoramic tomograms. A nickel stepwedge was attached to the film cassette to give a reference image on the radiographs. Four mandibles were radiographed and the optical density of a number of sites on the bone images measured. The calcium and phosphate content of the mandibles at these sites was measured by chemical analysis, using 3 mm diameter full thickness cores. The radiographically derived equivalent nickel thickness of the mandibular test sites was significantly correlated with calcium content (r = 0.62. P = 0.013), phosphate content (r = 0.633, P = 0.011), and dry bone weight (r = 0.541, P = 0.036), provided correction for soft tissue thickness was made. A clinical study is justified to determine whether the technique has sufficient accuracy to provide sequential data on individual patients and whether it may useful as a simple method of screening patients for mandibular osteoporosis.