Long-term changes in the anterior alveolar bone after orthodontic treatment with premolar extraction: A retrospective study.

Abstract

To evaluate the morphometric changes in maxillary and mandibular anterior alveolar bone after orthodontic treatment and retention for 18-24months by cone-beam computed tomography (CBCT). Thirty-four adolescent patients (12 males and 22 females; mean age: 14.29±1.24years) diagnosed with bimaxillary dentoalveolar protrusion and with extractions of the 4 first premolars were included. The labial and lingual (palatal) alveolar bone thickness, height and root length of the maxillary and mandibular anterior teeth were assessed using CBCT imaging at the pre-treatment (T1), post-treatment (T2) and retention phases (T3). Voxel-based superimpositions of the T2 and T3 images were performed, and the distances of incisal and apical movement between T2 and T3 were measured to determine whether relapses occurred. After orthodontic treatment, the labial and lingual (palatal) bone height decreased significantly (P<.05) and the labial thickness at the crestal (L1), midroot (L2), and apical levels (L3) had no significant change, while the lingual (palatal) bone thickness at all three levels decreased significantly (P<.05). After 18-24months of retention, the lingual (palatal) height and the lingual (palatal) thickness at the crestal (L1) level increased significantly (P<.05). There were no obvious incisal and apical movements of the anterior teeth between T2 and T3 (P>.05), indicating that no relapses occurred. Even though lingual (palatal) alveolar loss occurred due to the orthodontic treatment, the cervical alveolar bone seemed to recover over time. Therefore, appropriate camouflage treatment can be used in patients with bimaxillary dentoalveolar protrusion, and this treatment will not irreversibly deteriorate periodontal health and affect the orthodontic treatment stability.