RESUMO
PURPOSE: We sought to verify the cortical thickness and presence of tooth roots and inferior alveolar canal where miniplates are placed using the Champy technique to treat parasymphyseal fractures between the canine and premolar. We also studied these anatomic features at the same level anteriorly and posteriorly to the mental foramen. MATERIALS AND METHODS: A total of 80 dry, normal adult dentate human hemimandibles (40 male and 40 female) were studied. Verification was performed at 3 levels-above (S), below (I), and at the same height as the mental foramen (F). At each level, the thickness and proximity of the tooth roots and inferior alveolar canal were checked at 4 points; two anteriorly (4.5 and 9 mm) and 2 posteriorly (4.5 and 9 mm) to the mental foramen. RESULTS: The cortical bone was significantly thicker at level F (Fa2, 2.37 mm; Fa1, 2.43 mm; Fp1, 2.86 mm; Fp2, 2.89 mm) than the corresponding level S points (Sa2, 2.00 mm; Sa1, 2.11 mm; Sp1, 2.30 mm; Sp2, 2.45 mm) and level I points (Ia2, 2.11 mm; Ia1, 2.17 mm; Ip1, 2.39 mm; Ip2, 2.43 mm). Regarding the thickness and risk of injury, no difference was found between the points at levels S and I, where the miniplates are normally fixed with monocortical screws. No relationship was seen between the points at level F and the tooth roots or inferior alveolar canal. In contrast, a relationship between the points at level S and the tooth root and between the points at level I and the inferior alveolar canal was found. CONCLUSIONS: Above and below the mental foramen, the cortical bone for miniscrew anchorage was up to 3 mm thick. At the level of the foramen, the cortical plate will provide better anchorage and the insertion of miniscrews will be free of any risk of injuring the tooth roots or inferior alveolar canal.