Abstract:

Objective To evaluate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite. Methods A retrospective multicenter cohort study was conducted to investigate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲmalocclusion with anterior openbite. From 2010-2016, 122 patients from two domestic stomatological hospitals were included in our study. Patients were divided into four groups according to their treatment plans, namely, bilateral sagittal split ramus osteotomy (BSSRO), intraoral vertical ramus osteotomy (IVRO), BSSRO+Le FortⅠ, and IVRO+Le FortⅠ. All patients followed a standardized examination procedure at 6 and 24 months post-treatment. The observation indexes include overbite, mandibular plane angle, and intermaxillary angle. Results 1) The significantly reduced ratio of the overbite in the BSSRO+Le FortⅠand IVRO+Le FortⅠgroups were less than the BSSRO and IVRO groups at 6 and 24 months post-treatment. 2) The significantly increased ratio of the mandibular plane in BSSRO+Le FortⅠand IVRO+Le FortⅠgroups were less than BSSRO and IVRO groups at 6 and 24 months post-treatment. 3) The significantly increased ratio of the intermaxillary angles in BSSRO+Le FortⅠand IVRO+Le FortⅠgroups were less than the BSSRO and IVRO groups at 6 months post-treatment, while there was no stati-stical difference at 24 months post-treatment. Conclusion Bimaxillary surgery (BSSRO+Le FortⅠand IVRO+Le FortⅠ) is more effective than mandibular surgery to control vertical relapse.

Key words: skeletal class Ⅲ malocclusion, orthognathic surgery, open bite, overbite, mandibular plane angle, inter-maxillary angle