The oblique radiographic technique for bone height measurements on edentulous mandibles: A preclinical study and an introduction to the clinical use

Abstract

Objective. The aim of this study was to quantify the effect of mandibular angulation, position, and shape of the edentulous mandible on the distortion of its image on lateral oblique radiographs in a preclinical study. Suggestions for the clinical use of this technique are made. Study design. Five edentulous dry mandibles were used, varying in size from small to wide and equipped with metal bars in and on top of the mandible. The mandibles were radiographed at 9 different positions by tilting the mandible around the intercondylar axis and by using the oblique projection technique in a cephalostat. Results. The length of the images of the metal bars varied significantly when we tilted the mandibles from 20 degrees to –20 degrees. As a result of the effects of magnification and distortion, the image size varied from between 0.96% and 1.06% of the real size. Neither the size of the mandible nor the position of the bars was related to the degree of magnification. Conclusion. The oblique projection technique has limited geometric errors in depicting the edentulous mandible. For evaluative bone height measurements in patients with extremely resorbed mandibles treated with dental implants, it is a promising technique if the patient (specifically the mandible) can be positioned reproducibly in the apparatus. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:522-9)