Tomographic mapping of buccal shelf area for optimum placement of bone screws: A three-dimensional cone-beam computed tomography evaluation

Abstract

Introduction: Buccal shelf bone screws have become increasingly popular as a preferred method of skeletal anchorage in the mandibular arch. Anatomic variations and clinical experience suggest that width and slope of the bone at buccal shelf vary in different population groups, with some individual variations. Aims and Objectives: The objective of this study was to evaluate angulation of the bone screw of mandibular buccal shelf area, total bone width, thickness of the cortical bone, and proximity to neurovascular structures. Materials and Methods: Cone-beam computed tomography scans were used to obtain measurements of the buccal shelf region of 35 patients (18 females, 17 males; mean age, 23.6 years). Measurements were taken at three locations (L1, L2, and L3) and total bone width was measured at two levels from the cementoenamel junction (CEJ, H1 and H2). Bone screws were virtually placed and their proximity evaluated from digitally traced inferior alveolar neurovascular bundle. Results: Permissible angulation for placement of buccal shelf bone screw considering the safety distance from the root and avoiding excessive buccal projection to minimize cheek irritation was found to be 74.48 (SD ± 4.26). Total bone width was maximum at the distobuccal cusp of mandibular second molar (L3H2; 6.40 ± 1.35) when measured at the level of 8 mm from the CEJ. Bone screws were well within the safety range from causing any iatrogenic damage to the inferior alveolar neurovascular bundle at all the three aforementioned locations. Conclusion: Thus, area buccal to the mandibular second molar region seems to be the most favorable site for placement of buccal shelf bone screws in Indian patients.