Dentofacial Deformity Corrected by Surgery-First Orthognathic Surgery: from Selection Criteria, Surgical Occlusion Setup, to Influence on Skeletal Stability and Treatment Outcomes

Project: National Science and Technology CouncilNational Science and Technology Council Academic Grants

Project Details


Background and Purposes: The surgery-first approach is becoming popular because of several advantages, such as reduced treatment time, efficient tooth decompensation, and early improvement in facial esthetics. However, previous reports majorly worked on selected patients with mandibular prognathism. The aims of this study are to (1) examine the orthodontists’ stated reasons for their decisions of non surgery-first bimaxillary surgery for correction of various types of dentofacial deformity, (2) evaluate the accuracy of surgical occlusion setup, (3) evaluate the occlusal contact and its relation to skeletal stability, and (4) evaluate the treatment outcomes. Design: Prospective cohort studies. Setting: University hospital Craniofacial Center and Dental Department. Patients and Methods: We plan to recruit 240 patients (age  18 years) with dentofacial deformities (80 skeletal Class II, 80 skeletal Class III, 80 face asymmetry) who are going to have bimaxillary surgery: surgery-first (50 skeletal Class II, 50 skeletal Class III, 50 face asymmetry) and non surgery-first (30 skeletal Class II, 30 skeletal Class III, 30 face asymmetry). All patients undergo orthodontic records (including study casts, panorex radiograph, cephalometric radiograph, facial and intraoral photograph, CBCT) before treatment, one week and 12 months after surgery, and questionnaires before and after treatment. The pre-treatment orthodontic records are examined independently by five experienced orthodontists for their treatment preference and the reasons for it. Computer-aided surgical simulation is used to evaluate the accuracy of surgical occlusion setup. CBCT images are analyzed to obtain position of the maxilla and mandible after surgery and its relation to occlusal contact. Treatment outcome is evaluated by pre- and post-treatment questionnaires and orthodontic records by two calibrated orthodontists using the comprehensive clinical assessment criteria. Data Analysis: Independent t-test, chi-square test, and multiple linear regression, are used when indicated. Statistical significance is assumed for a p value of less than 0.05.

Project IDs

Project ID:PC10508-0623
External Project ID:MOST105-2314-B182-030
Effective start/end date01/08/1631/07/17


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