Abstract: Abstract: Objective To evaluate bone thickness of the infrazygomatic crest (IC) to analyze the risks for mini-screws insertion in adults with different vertical skeletal patterns. Methods The sample collecting CBCT of 67 adult patients with different vertical skeletal patterns who visited Affiliated Stomatological Hospital of Nanjing Medical University from 2016 to 2020. The bone thickness of the IC was evaluated at 70° and 65° angulations on the coronal slice in the mesial buccal root (MB) and distal buccal root (DB) of the maxillary left first molar and the region between the first and second molars (PR) on the left side. Results Bone thickness of the IC decreased from the mesial buccal root of the maxillary first molar to the region between the first and second molars. There were no statistics difference of bone thickness in IC between different skeletal patterns in the three selected measurement planes. Conclusion CBCT may be necessary to install mini-screws in the IC correctly. The best site to install mini-screws is buccal to the first molar mesial buccal root and at 70° angulation which will reduce the risk of invade the maxillary sinus.

Key words: vertical skeletal patterns, miniscrews, infrazygomatic crest, CBCT