Evaluation of skeletal changes in mandibular ramus height, corpus length, and mandibular angle changes following twin block appliance therapy using cone-beam computed tomography: A clinical prospective study

Aim and Objectives: This study aims to evaluate the skeletal changes in mandibular ramus height, corpus length, and mandibular angles changes following twin block (TB) functional appliance therapy using cone-beam computed tomography (CBCT). Methodology: Fifteen patients with skeletal Class II, growing of 9–14 years of age with mandibular retrognathism, were treated with TB functional appliance treatment. Pretreatment CBCT and posttreatment CBCT were taken (T0) before treatment and (T1) at the end of the 12 months following TB therapy. The data obtained are analyzed and compared for the skeletal changes in ramus height, corpus length, and mandibular angle changes following therapy. Student's paired t-test was used compare the pre- and post-treatment periods. Results: The test results demonstrate that the Ramus height (mm) in posttreatment period was significantly increased as compared to pretreatment period. The mean increase of 1.23 mm in the ramus height between pre- and post-treatment period was statistically significant at P < 0.001, and that the corpus length (mm) in posttreatment period was significantly increased as compared to pretreatment period. The mean increase of 3.35 mm in the corpus length between pre- and post-treatment period was statistically significant at P < 0.001, and demonstrate that the mean gonial angle (degrees) in posttreatment period was significantly increased as compared to pretreatment period. This mean increase of 3.18° in the gonial angle between pre- and post-treatment period was statistically significant at P < 0.001. Conclusion: TB appliance therapy increases the ramus height, and corpus length stimulating the growth of condyle in backward and upward direction and increases the gonial angle by backward rotation of mandible.