Comparative Effect of Twin-Block Appliance on Skeletal and Dental Indices in Patients with Skeletal Class Ii Malocclusion and Different Vertical Growth Patterns

Abstract

Aim: Malocclusion is a skeletal complication that requires orthodontic treatment, and class II malocclusion has been observed in many patients, for which twin-block appliance can be a treatment of choice. Due to scarcity of studies in this regard, the current study was carried out to evaluate the effect of this appliance on different vertical skeletal growth patterns as well as its prognosis. Materials and Method: In this retrospective study, the medical files of 66 patients with class II malocclusion treated by twin-block appliance by a faculty member orthodontist at Isfahan University of Medical Sciences were obtained, from which 37 files were selected via simple random sampling based on the determined criteria. The patients' lateral cephalometric radiographs before and after treatment were traced manually and analyzed afterwards. Based on Mandibular Plane Angle (MPA) index, they were divided into two groups, including normal facial growth pattern and vertical facial growth pattern. Result: In patients with normal facial growth pattern, only two cephalometric variables, overjet and ANB, showed statistically significant difference from among ten studied cephalometric variables. In patients with vertical facial growth pattern, SNB, overjet, N Perp/Pog, LAFH and ANB showed significant changes from among the ten cephalometric variables ( p<0.05). However, taking the length of treatment into consideration, SNA and SNB cephalometric variables were reported to be significant. Conclusion: Functional appliances are a good treatment of choice for patients with log faces and can be quite effective in controlling patients' MPA and vertical dimension, cause growth manifestation in anterior-posterior and vertical aspects of patients with vertical facial growth pattern and have equal or even more treatment effect on patients with vertical facial growth pattern than onthose with normal facial growth pattern.