Root proximity and cortical bone thickness effects on the success rate of orthodontic micro-implants using cone beam computed tomography.

OBJECTIVE: To evaluate factors (root proximity and cortical bone thickness) affecting the success rate of orthodontic micro-implants (OMIs) using cone-beam computed tomography (CBCT) images.

MATERIALS AND METHODS: We examined 172 OMIs (1.2-1.3 mm in diameter, 8 mm in length) implanted into the maxillary buccal alveolar bone of 94 patients (33 men, 61 women) with malocclusion. Root proximity and cortical bone thickness were measured, and the correlations between these measurements and OMI success rates were evaluated.

RESULTS: The overall success rate was 90.7% (156/172). The success rate increased as the distance between the root surface and OMI increased, showing a highly significant statistical correlation (P < .05). As the cortical bone thickness increased, the success rate increased, showing a slight, nonsignificant correlation (P > .05). Thus, the success rate of OMIs was affected more significantly by root proximity than cortical bone thickness.

CONCLUSIONS: When inserting OMIs, increasing the distance from the OMI to the root surface will significantly improve success rates.