Comparison of the effects of twin force bite corrector appliance in upper second molar extraction and nonextraction cases

The purpose of this study was to evaluate the dentoskeletal effects of Twin Force Bite Corrector appliance, a fixed functional appliance that is used in the treatment of class II malocclusions, on patients requiring the extraction of maxillary permanent second molars and non-extraction cases by using cephalometric radiographs. The sample consists of 45 Class II patients with lack of growth potential were divided into two groups. 23 of these 45 patients (19 females, 4 males, mean age 14.93 ± 1.35 years) had their upper second molar teeth extracted as a part of their orthodontic treatment plan and, 22 patients (13 female, 9 male, mean age 14.25 ± 1.71 years) were treated without tooth extraction and Twin Force Bite Corrector appliance was used in both groups to correct Class II malocclusion. . Lateral cephalometric radiographs were taken at the beginning of the treatment (T0) and immediately after the removal of the Twin Force Bite Corrector (T1). A significant decrease in SNA angle was observed on patients whose orthodontic treatments were performed with tooth extraction. (p <0.05), SNP and SNPog angles showed a statistically significant increase in patients treated without tooth extraction (p <0.01). The retrusion of upper incisor was found statistically significant in the tooth extraction group (p <0.01). It was found that the improvement in maxillo-mandibular relationship was due to protrusion of lower incisors and retrusion of upper incisors and the changes were mostly dentoalveolar in nature rather than skeletal. Clockwise rotation was observed in the occlusal plane and changes were observed in the vertical measurements related to this plane, however, no change in SN-GoGn angle was observed. There was no significant difference in the the amount of first molar distalization in either treatment groups. When the treatment effects were compared; no statistical difference was found between any of the parameters between the extraction and the non- extraction treatment groups. In both treatment groups, the dento-skeletal effects of the Twin Force Bite Corrector appliance and the duration of treatment were found to be similar. Key Words: Class II malocclusion, Twin Force Bite Corrector, Upper second molar tooth extraction.