Alveolar Bone and Root Length Changes Following En-masse Retraction with Corticotomy assisted Orthodontic Treatment

Abstract

Introduction: Corticotomy is an effective method of accelerating the orthodontic treatment and has been proposed to increase the volume of the alveolar process and decrease root resorption. Patients with dentoalveolar protrusion usually have thin alveolar bone and bony defect. Pushing the tooth against the thin cortical bone may cause alveolar bone defect and root resorption. So retraction of the anterior teeth combined with corticotomy of the alveolar bone can offer an effective alternative option that minimize the risk of movements of the anterior teeth and root resorption. Objectives: To compare alveolar bone and root length before and after en-masse retraction with corticotomy in bimaxillary protrusion patient. Materials and methods: 14 subjects were selected from patients who required the removal of first premolars in upper and lower arches, en masse retraction and corticotomy as a part of their orthodontic treatment. Cone beam computed tomography analysis was used to compare alveolar bone width at crestal, mid- root and apical level, alveolar bone height at mesial, distal, labial and lingual sides and root length changes between pretreatment and postretention in all anterior teeth Result: Maxillary and mandibular labial bone thickness increased 0.58 mm., 0.65 mm, respectively .Maxillary lingual bone thickness decreased 0.18 mm, but found increased 0.27 mm. in mandibular lingual bone thickness. No significant alveolar bone height changes were found in all anterior teeth. Maxillary and mandibular alveolar bone height decreased 0.19 mm., 0.18 mm. respectively. Significant root resorption occurred in all anterior teeth. Average root resorption in all anterior teeth was 1.01 mm. Conclusions: Corticotomy not only accelerates the orthodontic treatment but also provides the advantage of increased alveolar width. This study showed an average increase in alveolar bone width following corticotomy. However, there were also sites, maxillary lingual bone thickness, in which there was a decrease in alveolar width. No significant alveolar bone height changes were found. But significant root resorption occurred in all anterior teeth