Evaluation of alveolar bone remodeling around maxillary and mandibular central incisors during orthodontic extraction treatment using Conebeam CT

Abstract

This study was conducted on adult patients who underwent orthodontic extraction treatment. Lateral cephalometric X-ray and Cone Beam Computed Tomography (CBCT) were conducted on the subjects before and after treatment. The buccal and palatal alveolar bone thickness of maxillary and mandibular central incisors at the 3 mm, 6 mm, and 9 mm apical levels from CEJ, the distance from CEJ to the buccal and palatal alveolar crestal bone, and the buccal and palatal alveolar bone area from CEJ to 9BT level were measured, and the changes in the measurement variables before and after treatment were analyzed. The subjects were divided into the tipping and torque groups according to the movement of anterior teeth observed in lateral cephalometric X-ray, followed by intra-group analysis and correlation analysis. The results of this study were as follows.1.After orthodontic extraction treatment, the 6BT and 9BT of the maxilla (p<0.01)(p<0.001) and the 6BT and 9BT of the mandible (p<0.05)(p<0.001) significantly increased. Meanwhile, the PT at 3 mm, 6 mm, and 9 mm apical levels from CEJ and PABA significantly decreased in both maxilla and mandible (p<0.001).2.After orthodontic extraction treatment, the BABL decreased by 0.22 mm (p<0.01), and the PABL decreased by 3.83 mm (p<0.001) in the maxilla. Meanwhile, the BABL decreased by 2.59 mm (p<0.01), and the PABL decreased by 5.82 mm (p<0.001) in the mandible. 3.In the case of Torque group, in the maxilla and mandible, the 6BT (p<0.01) and the 9BT (p<0.001) significantly increased, whereas the 3PT, 6PT, and 9PT significantly decreased in both maxilla and mandible (p<0.001). The PABL (p<0.001) in the maxilla and the BABL and PABL (p<0.01)(p<0.001) in the mandible significantly decreased. BABA in the maxilla (p<0.01) and mandible (p<0.05) significantly increased and PABA in the maxilla (p<0.001) and mandible (p<0.001) significantly decreased.4.In the case of Tipping group, no significant difference in the BT was found in the maxilla, but the 3BT (p<0.001) decreased and 9BT (p<0.05) increased in the mandible. 3PT, 6PT (p<0.001) and 9PT (p<0.01) significantly decreased in the maxilla and 3PT (p<0.05) and 6PT (p<0.01) significantly decreased in the mandible. In addition, BABL and PABL in the maxilla (p<0.05)(p<0.001) and mandible (p<0.001) significantly decreased. PABA (p<0.001) in the maxilla and BABA (p<0.01) and PABA (p<0.01) in the mandible significantly decreased.5.After orthodontic extraction treatment, the change of the axis of maxillary and mandibular incisors and the root movement were highly correlated with the alveolar bone thickness and area. In orthodontic extraction treatment for adults who have reduced alveolar regeneration compared to adolescents, incisors movement type should be determined considering alveolar bone thickness and periodontal condition before treatment. In the maxilla, as the resorption of the buccal alveolar bone is insignificant, and that of the palatal alveolar bone is significant but in the mandible the resorption of both buccal and palatal alveolar bone is significant. So, mandibular incisor retraction plan should be more carefully established.