Evaluation of bone thickness changes associated with en masse retraction facilitated by corticotomy and piezocision using cone beam computed tomography

Objective: The purpose of this study was to assess the bone thickness changes accompanied en-masse retraction assisted by corticotomy and piezocision by using CBCT (cone beam computed tomography). Subjects and Methods: Twenty subjects having Class I malocclusion with bimaxillary protrusion were included in the study. The patients were randomly divided into two equal groups; group I: flap group and group II: piezocision group. CBCT images were obtained before treatment (T1) and after space closure (T2). The alveolar bone thickness was assessed on the labial and lingual sides at the cervical, middle and apical thirds of the roots of the upper and lower anteriors. Results: Group I demonstrated a significant increase in the cervical labial bone thickness of the upper incisors while no significant change was detected in group II. Both groups revealed a significant decrease in the bone thickness of the cervical labial third of the lower anteriors. The labial bone thickness of the middle third showed no significant change except the upper left lateral incisor which revealed a significant decrease in group I. The labial bone thickness at the apical third showed no significant change in both groups. For both groups, the lingual bone thickness showed a significant decrease for all anteriors in the cervical and middle thirds. The apical third revealed no significant changes except the canines which showed a significant decrease in group I. Conclusion: En-masse retraction aided with either corticotomy or piezocision in bimaxillary protrusion cases showed significant bone thickness changes on the labial and lingual sides.