BONE HEIGHT MEASUREMENTS ON PANORAMIC RADIOGRAPHS - THE EFFECT OF SHAPE AND POSITION OF EDENTULOUS MANDIBLES

Objective. The aim of this study was to quantify the effect of mandibu lar angulation, position, and shape of an edentulous mandible on the d istortion of its image in panoramic radiographs. Study design. Five ed entulous dry mandibles varying in size from small to wide and equipped with metal bars in and on top of the mandible were used. The mandible s were radiographed at nine different positions by tilting the mandibl e posteriorly around a transversal axis, using an orthopantomograph. R esults. The length of the images of the bars on top of the mandible in creased significantly by tilting the mandibles from +20 degrees to -20 degrees. The magnification factor of the images of the intrabony bars in the mandible was the largest at 0 degrees and decreased significan tly by both decreasing or increasing the inclination. The size of the mandible was not related to the magnification factor. Conclusion. For both diagnostic and evaluation purposes of the edentulous mandible, th e panoramic radiograph is not a reliable radiographic technique unless meticulous precautions are taken for reproducible positioning of the patient in the apparatus.