Abstract: Objective: To provide some references of using micro-implant anchorage in adult of skeletal Class Ⅱ malocclusion by measuring the thickness of buccal cortical bone and the buccolingual bone of different insertion angle type in the maxillary second premolar and first molar area by cone-beam CT (CBCT). Methods: The maxillary posterior area of 30 adult patients (18<year<40) were scanned and reconstructed by CBCT. The cortical bone and the bone thickness were measured at 4, 6, and 8mm from the alveolar crest with 45°, 60°, 90° angle in maxillary posterior interdental area between first molar and second premolar. The data were analyzed statistically. Results: The cortical thickness of buccal bone in maxillary posterior interdental area was thicker at 8mm than 6mm. 4mm was the thinnest with the same insertion angle (P<0.05). The cortical bone thickness was the thickest with 45° insertion angle and the thinnest with 90° insertion angle at the same height level (P<0.05). Conclusion: The study suggested that the conical bone thickness is thicker when the implantation location was more away from the alveolar crest, and the insertion angle with 45° also can provides best cortical bone thickness at same height level.

Key words: Micro-implant, Insertion angle, Cortical thickness, CBCT