Objective:To explore the relationship between stable micro-implant anchorage and the bone thickness and density by analyzing the cone-beam computed tomography（CBCT）data of the adolescents with class Ⅲ malocclusion who underwent successful micro-implant anchorage implantation for maxillary protraction. Methods:A total of 20 patients with successful anchorage implantation for maxillary protraction were selected as experimental group

and 20 patients with failed implantation as control group. The density of the cortical bone and cancellous bone and the thickness of the maxilla on both sides before and after the implantation were measured and analyzed using NNT software based on the data of CBCT. Results:In the experimental group

the density of the cortical bone was（1 078 ± 280.5）HU

the density of the cancellous bone was（395.4 ± 149.6）HU

and the bone thickness was（6.4 ± 1.3）mm; in the control group

the density of the cortical bone was（764.0 ± 180.4）HU

the density of the cancellous bone was（356.4 ± 164.2）HU

and the bone thickness was 3.9 ± 1.4 mm. There were significant differences in the density of the cortical bone and the bone thickness between the experimental group and the control group（P <0.05）

while no significant difference was found in the density of the cancellous bone. Conclusion:The cortical bone density and thickness of the maxilla are significantly higher in the adolescents with class Ⅲ malocclusion who have successful micro-implant anchorage implantation for maxillary protraction than in those with failed implantation

which suggests that CBCT data should be analyzed and studied before the micro-implant anchorage implantation in adolescents

in order to reduce the risk of failure and increase the success rate of implantation.