Cephalometric Evaluation of Cl. III Patients Treated with Chin Cap: A Self Controlled Clinical Trial

Statement of Problem: The prevalence of Cl. III malocclusion has been reported to be various among different races (3-5%). Early treatment of this malocclusion is highly recommended. This study was performed to determine the effect of chin cap in early treatment of Cl. III malocclusion on the nasomaxillary complex and mandible. In a cases control study, 40 Cl. III patients treated by upper jaw appliance and chin cap, on the basis of reverse overjet and/or concave profile, were chosen. The mean force was measured to be 200 gr on each side for 18 hours/day. The mean age was 8.5±2 years old while 55% were female and 45% were male. The analysis of cephalometric data before and after treatment were done considering the skeletal, dental and soft tissue variables. The mean treatment period was 22+12 months and was continued until 34 months. Cephalometric measurements showed the following changes: SNA=0.5±1.313, Co-Po.A=2.7±2.348, SNB=-1.7±1.555, GoGnSN=1.7±1.605, NPog-FH=1.1±2.466, LAFH=2.8± 2.772, Wit’s=2.7±1.872, ANB=1.1±1.331, IMPA=-3.1±4.298, 1 to NA=3.1±5.078 demonstrating an increase in anteroposteiror indices of maxilla, vertical change of mandibular growth and a change in the angle of anterior teeth of upper and lower jaws. Changes in upper and lower pharyneal space were not statistically significant. There was a negative correlation between the effect of chin cap therapy and age which was appeared in the early stages of its application.