Cephalometric changes following rapid maxillary expansion and facemask therapy in class III malocclusion

Treatment of patients with class III malocclusion is one of the most challenging problems in orthodontic practice. This problem which causes functional and esthetic problems can result from prognathism of mandible or deficiency of nasomaxillary complex or a combination of both. It has been estimated that the incidence of this type of malocclusion in Iranian population is between 7.22 – 19.5 percent. The importance of early identification and treatment of this malocclusion is significant. The aim of this study was to determine the cephalometric changes following combined use of rapid maxillary expansion and facemask therapy in class III malocclusion. Methods & Materials: In this quasi experimental prospective clinical trial, 15 Iranian patients (6 males and 9 females with a mean age of 8.6 years) were selected. They were first treated with rapid maxillary expansion for 14 days prior to facemask delivery. Then facemask therapy was initiated untill normal canines and molars relationship and a normal overjet were achieved. Cephalometric means (consist of 11 angular and 8 linear measure) before and after treatment were calculated and compared with paired t-test to determine significant differences. Cephalometric analysis showed following changes: SNA=1.3±1.6, SNB=-0.5±1.6,ANB=1.7±2.3,Gonial Angle=-1.4±4.1,Articular Angle=-6±27.5, SNPog=-0.7±1.7, Inclination Angle=2.3±7.3, Y axis Angle=1.5±3.4, Mandibular Plan Angle=2.3±3.3, Occlusal Plan to SN=1±5.4, NSAr=0.8±2.3,PFH/AFH=0.8±1.9,N┴FH to A=1.1mm±1.9, N┴FH to Pog=1mm±4.6, Maxilla length=2.3mm±2.9, Mandible length=0.4mm±0.8, Overjet=3.8±2.7,Overbite=-0.8mm±1.5, Wit’s appraisal=2.4±2.5. This results indicate that facemask and rapid maxillary expansion improve class III malocclusion by increase in maxillary growth in anterioposterior dimension and a slight limitation of mandibular growth.