A RADIOGRAPHIC STUDY ON THE MANDIBULAR CANAL

하악관에 관한 방사선학적 연구

The purpose of this study is to improve the availabilities of radiographic technics as diagnostic method related to mandibular canal in dental clinic. For this study 12 dry mandibles were used and 12 orthopantomograms were taken for measuring the gonial angle and the angle of mandibular canal to inferior border of mandible. 12 sites located between the 1st premolar to the 3rd molar region of 3dry mandibles were selected randomly, for measuring the vertical image magnification rates on three films; intraoral film, orthopantomogram, and computed tomogram, respectively and the thickness of cortical bone, and for observing bucco-lingually and supero-inferiorly location of the mandibular canal. The acquired results were as follows: 1. The means of the gonial angle and the angle of mandibular canal to inferior border of mandible were 123.9° and 143.5° And the two angles of dry mandible in alveolar crest stage were greater than in alveolar socket stage. 2. The vertical image length on intraoral film by paralleling technic was magnified by 3.07% on the average, the length on orthopantomogram by 18.49%, and the length on computed tomogram by 0.27%. 3. Observation of the bucco-lingually positional relationship of the mandibular canal was impossible by occlusal projection with the cross section technic and intraoral standard projection with the Clack's rule, however, possible by computed tomogram. 4. The thickness of the cortical bone of mandible was thickest in inferior border, and thicker by 6.59% at buccal side than at lingual side.