Optimal sites and angles for the insertion of orthodontic mini-implants at infrazygomatic crest: a cone beam computed tomography (CBCT)-based study.
Qinxuan Song, Fan Jiang, Maolin Zhou, Tianle Li, Shizhen Zhang, Lu Liu, Lingling Pu, Wenli Lai, Long Hu
Abstract
BACKGROUND AND OBJECTIVES: Both cortical and overall bone thicknesses of the infrazygomatic crest (IZC) were measured to determine the optimal areas for mini-implants into the IZC. The impact of insertion sites, heights and angles, sex and age on bone thickness were evaluated. MATERIALS AND METHODS: In this study, cone beam computed tomography (CBCT) images of 32 patients were included. The cortical bone thickness (CBT) and overall bone thicknesses (OBT) of IZC were measured at different insertion sites between the maxillary first and second molars (site 61, 62, 63, 67, 71, 72 and 73), different heights (0 to 12 mm from alveolar bone crest) and different angles (0 to 90 degrees from the reference line). RESULTS: OBT was the thickest at site 63, followed by site 73. For each site, the insertion height where OBT was the thickest decreased with the increase of angle CBT and OBT were significantly influenced by sex and age. The percentage of root contact was significantly influenced by insertion heights and angles, not by sites. The recommended regions in the IZC for mini-implants were mapped. CONCLUSIONS: Both CBT and OBT in the infrazygomatic crest were influenced by insertion sites, heights, and angles. Sex and age had an impact on CBT and OBT. The optimal insertion heights and angles were 12 mm to 18 mm from the occlusal plane, and 40 to 70 degrees for mini-implants at IZC.