Abstract: Objective: To evaluate and compare buccal thickness of cortical bone and root proximity for optimal mini-implants placement at interradicular sites between canine and the first premolar. Methods: Twenty-nine Cone Beam CT images were randomly selected from Hospital of Stomatology, Wuhan University. Thickness of cortical bone and root proximity between canine and first premolar at the apical level of 3, 4, 5, 6 and 7 mm from the alveolar crest was measured for further statistical analysis. Results: The thickness of buccal cortical bone at both maxillary and mandibular interradicular sites between canine and the first premolar was greater than 1mm. This thickness in the maxilla increased as the level went up from 3mm to 7mm, differed from that in the mandible, which was the least at the level of 4mm and increased from the level of 5mm to 7mm. The root proximity in both maxilla and mandible was greater than 2mm and increased as the level went up from 3mm to 7mm. Both the thickness of cortical bone and root proximity showed no significant difference at all levels between maxilla and mandible. Conclusion: The interradicular sites between canine and first premolar from the apical level equal to or greater than 3mm from the alveolar crest are the ideal sites for mini-implants placement.

Key words: Oral and maxillofacial Cone Beam CT, Mini-screws, Cortical bone thickness, Root proximity, Anchorage