Evaluation of Infrazygomatic Crest Bone Thickness for Extra-Alveolar Temporary Anchorage Device Placement: A...

The infrazygomatic crest (IZC) is a favorable site for extra-alveolar temporary anchorage device (TAD) placement during orthodontic treatment. However, anatomical variations in bone thickness necessitate individualized preoperative assessments to ensure safe and predictable TAD placement. This retrospective cone-beam computed tomography (CBCT) study evaluated IZC bone thickness at standardized levels and compared measurements according to sex and skeletal malocclusion.

A total of 150 pre-treatment CBCT scans (300 IZC sites) of patients aged 18-35 years were analyzed. Total bone thickness, cortical bone thickness, and available bone thickness were measured at 11 mm and 13 mm apical to the cementoenamel junction of the maxillary first molar along a 70^o insertion trajectory. Measurements were compared between sexes using independent t-tests and among skeletal malocclusion groups (Class I, II, and III) using one-way analysis of variance (ANOVA) with Tukey's post hoc test.

Measurements at 13 mm showed greater total (7.85 mm) and available bone thickness (6.37 mm) than those at 11 mm (6.42 mm and 5.14 mm, respectively). Males demonstrated significantly greater bone thickness than females at both levels (p<0.001). Skeletal Class III subjects exhibited the greatest total and available bone thickness, followed by Class I and Class II subjects (p<0.05), whereas cortical bone thickness did not differ significantly among the groups.

The IZC provided adequate bone for extra-alveolar TAD placement, with a 13 mm level offering greater bone availability. Significant variations according to sex and skeletal malocclusion supported individualized CBCT-based treatment planning to optimize the safety and predictability of TAD placement.