Stereographic assessment of mandibular canal in relation to the roots of impacted lower third molar using multiprojection narrow beam radiography.

The position of the mandibular canal in relation to the superimposed roots of 173 impacted lower 3rd molars was evaluated radiologically. A multiprojection narrow beam radiography (MNBR) technique recently developed for oral radiography was applied in this study. This method enables stereoscopic examination of the area of interest. The mandibular canal was located bucally to the roots of 105 (61%) teeth, lingually to the roots of 57 (33%) teeth, and between the roots of 6 (3%) teeth. The relationship of canal to roots of 5 (3%) teeth was not possible to determine. Disagreement between radiological assessment and clinical observation was found in 4 (5%) of 80 operated teeth. The canal was visible at operation in 23 (29%) cases, which was predicted at stereographic examination in 21 (91%) cases. The MNBR stereographic technique is a useful method with high sensitivity (0.83) for evaluating the bucco-lingual relationship of the mandibular canal to the roots of a 3rd molar.