Introduction: Skeletal Class II malocclusion repair is a frequent orthodontic strategy, and the twin block appliance has been used more and more frequently to treat Class II malocclusions in growing children. In order to solve Class II division 1 malocclusion in developing patients with a retrognathic mandible, this study was planned to evaluate the dental, skeletal, and soft tissue implications of employing the twin block appliance. Materials and methods: A treatment group comprising fifteen skeletal Class II developing patients with retrognathic mandibles, who were planned for treatment utilizing the twin block appliance had cone beam computed tomographic radiographs taken before (T1) and after (T2) the correction of skeletal class II malocclusion. Their mean age was 10.8 ± 1.2 years. A second skeletal Class I control group with matching ages to the experimental group (11 ± 1.1 years) had two CBCT radiographs with an interval period matching to T1 and T2 of the first group. Using a paired t-test, dental, skeletal and soft tissue changes were compared at T1 and at T2 for both groups. Unpaired T-test was utilized to compare between both groups. Conclusion: Growing patients with skeletal Class II malocclusion characterized by retruded mandible can be efficiently treated with the twin block device. Both Jaws have undergone skeletal and dentoalveolar alterations, which together account for this efficacy. The soft tissue profile was also enhanced.