Abstract: [Objective]The aims of this study were to measure the buccolingual alveolar bone thickness between the maxillary central incisors by using cone beam computed tomography and to explore the optimal insertion height and angle for orthodontic mini-implant placement. [Material and Methods] Three-dimensional reconstruction was performed on CBCT images of 80 normal persons aged 12-25 years .For each subject ,the buccolingual alveolar bone thickness of 12 insertion paths on the median sagittal plane was measured at four different levels of 14.0,16.0,18.0 and 20.0mm from the reference plane and three angles of 60°,75°, and 90° with the surface of the cortical bone. [Result]Mean buccolingual alveolar bone thickness of every site was greater than 7 mm. At the same height level, the bone thickness is the largest at the angle of 60°, the difference was statistically significant. Male has greater bone thickness than female at most sites. [Conclusion]The orthodontic mini-implant with 6mm length in the bone can be placed between the maxillary central incisors. In clinical application, there was more alveolar bone with the insertion angle of 60°.The insertion height is recommended according to clinical needs and the patient's soft tissue condition.

Key words: Maxillary central incisor, Nasopalatine Canal, Orthodontic mini-implant, Cone Beam Computed Tomography