Comparison of alveolar bone loss around incisors in normal occlusion samples and surgical skeletal class III patients

To test the hypothesis that there is no difference in vertical alveolar bone loss and alveolar bone thickness around maxillary and mandibular central incisors in normal occlusion samples and skeletal Class III malocclusion patients.

The study sample comprised 20 Korean normal occlusion subjects (mean age, 22.1 years; group 1) and patients with skeletal Class III malocclusion with anterior open bite (mean age, 22.4 years; group 2). Three-dimensional (3D) cone beam computed tomography (CBCT) images were taken before orthodontic treatment, and sagittal slices chosen at the labio-lingually widest point of the maxillary and mandibular right central incisor were evaluated, respectively. The amount of vertical alveolar bone loss and/or alveolar bone thickness of the labial and lingual plate at the root apex were measured.

Group 2 had statistically significant more vertical bone loss than group 1 (P < .05). Alveolar bone at the apex was significantly thinner in group 2 (P < .05), except for the maxillary incisors. Mandibular incisors showed greater alveolar bone loss than was seen in maxillary incisors in both groups, especially at the lingual side in group 2 (P < .05). Overall, alveolar bone thickness at the apex was wider than cementoenamel junction (CEJ) width, except for the mandibular incisors in group 2, for which the percentage was 81.33%.

The hypothesis is rejected. Special care should be taken to avoid aggravating preexisting alveolar bone loss in the anterior teeth, especially in the mandible, in skeletal Class III patients, who may be more vulnerable to alveolar bone loss during orthodontic treatment.