Cephalometric evaluation of skeletal changes following Twin-Block functional appliance therapy

Abstract

The question whether the correction of Class II malocclusion is dental or skeletal has not been answered yet. The purpose of this study was to clinically evaluate the pre and post treatment dental and skeletal changes followed by growth modification. Method and material: This study conducted in Tabriz University of Medical Sciences, Dental Faculty n 1389-90. The study included 12 boys (12-15 years) and 18 girls (10-13years) treated in a private orthodontic clinic in Tabriz using a modified type of twin block appliance. The pre- treatment and post-treatment of lateral cephalograms of the patients were traced and 18 hard tissue measurements were measured. The SPSS 17 analytic software and paired t-test were used to compare the averages before and after treatment. P-Values less than 0.05 were considered significant. Results: In postero-Anterior Jaw relationships, although SNA and SNB angles did not showed significant changes by themselves however, cumulative action resulted a significant reduction of ANB angle by 1.67 degree( p=0,0001). The reduction of ANB angle beside a significant reduction of Convexity angle by 3.56 degree (p=0.0001) could describe the improvement of skeletal Class II correction in most of the patients. Vertically, an increase of LAFH/TAFH by 0.53% was noted significant. (p=0.002) but other variables such as Basal angle, FMA, Y-axis, Gonial angle and Inclination Angle remained unchanged and did not showed statistically significant increase (P>0.05). Dentally, the inclination of Upper incisors (U1-NA) were decreased by 2.65mm but this was not significant (p>0.05). The inclination of lower incisors (IMPA and L1-NB) was not changed significantly (p> 0.05) The overjet was decreased by 4.183 mm that was significant (p=0.049). Conclusion: The skeletal and dental changes are both responsible for successfully treated Class II malocclusions mandibular deficiency by proper designed Functional appliances.