Assessment of the mandibular buccal shelf for orthodontic anchorage: Influence of side, gender and skeletal patterns.

Objectives: To evaluate bone height and thickness in the mandibular buccal shelf region and to compare differences between anatomical sites according to gender, side and vertical and sagittal skeletal patterns.

Settings And Sample Population: Multislice computed tomography (MSCT) images of 94 subjects (51 females and 43 males) were previously obtained as part of preoperative planning for orthognathic surgery.

Methods: Measurements were performed in three different regions of the mandibular buccal shelf: mesially, towards the central groove and distally to the second molars. Bone thickness measurements were obtained perpendicularly 3, 5 and 7 mm below the bone crest towards the mandible outer cortex. Bone height was measured 3 mm away from the bone crest perpendicularly to the outer cortex of the base of mandible.

Results: There was an increase in bone thickness in the posterior and basal directions. The increase in bone thickness ranged from 1.8 to 7.1 mm. Greater bone height was found in the anterior direction. The increase in bone height ranged from 17.5 to 22.5 mm. Hypodivergent and Class III subjects showed significantly greater bone thickness (P < .05). Significantly greater bone height was found mesially to the second molar in Class III subjects compared with Class I subjects (P < .05) and in hyperdivergent males compared with hypodivergent males (P < .05).

Conclusions: The region distal to the second molar is the most appropriate for the insertion of extra-alveolar mini-screws in terms of bone thickness. Hypodivergent and Class III subjects showed greater bone thickness in the mandibular buccal shelf region.