Early Treatment of Class III Patients To Improve Facial Aesthetics and Predict Future Growth

The objective of this study is to determine the profile changes in Class III patients treated with protraction facemask and propose the use of serial cephalometric radiographs and a Growth Treatment Response Vector (GTRV) analysis to predict excessive mandibular growth. Serial cephalometric radiograph of 40 Class III patients who were treated with protraction facemask were included in the study. Cephalometric radiograph was taken at the initiation of treatment (T1) and 6 months after maxillary protraction (T2). Changes in skeletal and soft tissue profiles were determined using well-known cephalometric analyses. Data were analyzed using a Student t test. To determine the GTRV ratio for the successfully and unsuccessfully treated cases, post-treatment records were used to divide patients into successfully and unsuccessfully treated groups. The criteria for successful treatment included a positive overjet of greater than 1 mm at the follow-up visit. Horizontal growth changes of the maxilla and mandible were determined by superimposition of the follow-up radiograph on the post-treatment radiograph. The GTRV ratio was calculated using the formula GTRV = Horizontal growth changes of the maxilla / Horizontal growth changes of the mandible. Results show that early treatment with protraction facemask can improve the skeletal and soft tissue facial profiles. The lip posture was improved. The normal incisal relationship (overjet) that was achieved had a significant impact on the soft tissue overlying both the upper and lower incisors, resulting in improved lip competence and posture. The mean GTRV ratio for the successful group was found to be 0.49 with a range of 0.33 to 0.88. Class III patients with mild to moderate skeletal malocclusion and a GTRV ratio that falls within this range can be successfully camouflaged with orthodontic treatment. The mean GTRV ratio for the unsuccessful group was found to be 0.22 with a range of 0.06 to 0.38. Patients with excessive mandibular growth together with a GTRV ratio that falls below 0.38 should be warned of future need for orthognathic surgery. * Professor and Chair, Department of Orthodontics, West Virginia University, Morgantown, West Virginia, USA † Professor Emeritus, The University of Hong Kong and former Dean and Chair Professor and Head of the Department of Children's Dentistry and Orthodontics of the Faculty of Dentistry, University of Hong Kong