Periodontal consequences of mandibular incisor proclination during presurgical orthodontic treatment in Class III malocclusion patients.

OBJECTIVE To test the hypothesis that periodontal changes are similar between proclined and minimal-changed mandibular incisor position groups during presurgical orthodontic treatment for Class III orthognathic surgery. MATERIALS AND METHODS The following measurements were performed before and after presurgical orthodontic treatment of 75 patients (proclination group, 39 subjects; minimal-change group, 36 subjects): clinical crown length, sulcus and bone probing depths, and width of attached gingiva from clinical examination; infradentale-to-MP (perpendicular distance of infradentale to mandibular plane) from examination of lateral cephalograms; and the distance between the cementoenamel junction and alveolar crest from examination of periapical radiographs. Data were compared between the two groups, and a regression analysis was performed to investigate factors affecting the periodontal changes. RESULTS In both groups, clinical crown length and bone probing depth increased during presurgical orthodontics (P < .05). Infradentale-to-MP and the width of attached gingiva decreased more in the proclination group than in the minimal-change group (P < .05). Proclination and protrusion of the mandibular incisors, and treatment duration affected the periodontal changes. CONCLUSIONS The null hypothesis was rejected. Proclination of the mandibular incisors for decompensation in Class III surgery patients seems to result in labial alveolar bone recession and a decrease in width of attached gingiva. However, the amount of the periodontal recession appeared to be clinically insignificant.