Orthodontic tooth movement: Bone formation and its stability over time

IntroductionOrthodontic tooth movement can lead to the creation of bone. The purposes of the study were to investigate the amount of bone formed in orthodontic patients during treatment (maxillary canine distalization) and retention and to assess the long-term stability of the new bone.MethodsThe sample consisted of 80 patients with 128 missing lateral incisors who were treated with distalization of the maxillary canines. They were examined at the beginning of orthodontic treatment (T1), at the end of treatment (T2), 2 years after treatment (T3A), and 5 years after treatment (T3B). The influence of the canine’s inclination and its distance from the central incisor at T1 on the amount of bone created and the bone mass stability over time were assessed. Vestibular width of the alveolus was measured on casts at the level of the bone ridge and 5 mm apically from the alveolar ridge. Canine inclination to the alveolar ridge was recorded, as well as the height of the alveolar ridge.ResultsDuring treatment, T1 to T2, the alveolar ridge width was reduced by 4%, and the height decreased by 0.26 mm; during the retention periods (T2-T3A, T2-T3B), the alveolar ridge reduction was 2% on average, with individual variances, and height decreased by 0.38 mm on average. No correlation was found between canine inclination or between the canine distance from the central incisor at T1 and the amount and stability of the bone created by the orthodontic movement.ConclusionsThe bone created through orthodontic tooth movement was stable in both the horizontal and vertical directions. Changes in the width of the alveolus were not related to the amount of bone at the place of agenesis at T1. When the canine erupts next to the central incisor, favorable conditions affect the formation of the bone mass through distalization of the canine at the site of the missing lateral incisor.