Estimation of Mandibular Buccal Shelf Cortical Bone Thickness at Variable Sites, Heights and Angulations in Three Different Growth Patterns-A Cone Beam Computed Tomography Study.

OBJECTIVES

To compare mandibular buccal shelf cortical bone thickness in different skeletal growth patterns for temporary skeletal anchorage device placement using Cone Beam Computed Tomographic imaging (CBCT).

METHODS

Forty-two CBCT scans were selected and separated into three groups: Horizontal, normal and Vertical, based on cephalometric angular and linear measurements. Five sites were examined on left side of the mandible-Distal of first molar, Interdental between the first and second molar, Mesial, Middle and Distal of lower second molar. Buccal shelf cortical bone thickness (in mm) at 5 and 7 mm height from alveolar bone crest and at 70 and 80 degree angulation from the occlusal plane were measured in all the three groups.

RESULTS

Significant variance (p < 0.001) in thickness of cortical bone was seen among the three groups: higher in horizontal followed by vertical and normal groups and higher at 7 mm height from alveolar crest and 80° angulation distal to mandibular second molar in each group. Overall, the findings demonstrated a consistent trend of greater cortical bone thickness in females compared to males at several sites, particularly in the posterior mandibular region.

CONCLUSION

Based on the results, placing a buccal shelf bone screw is safer and more stable in horizontal individual, compared to normal and vertical individual because of greater cortical engagement. At a site distal to 2nd molar, at a height of 7 mm from alveolar bone crest and angulating at 80° gives the best cortical bone engagement, which in turn increases the primary stability and decreases the chances of failure of buccal shelf implant. Across all growth patterns, posterior mandibular inter-radicular areas (7 M, 7 Mi, and 7D) exhibit greater variability in cortical bone thickness between genders with increased bone thickness in females compared to males.