Dentoskeletal effects of the Bite-Jumping Appliance and the Twin-Block Appliance in the treatment of skeletal Class II malocclusion: a randomized controlled trial.

OBJECTIVES: The current parallel group, randomized controlled trial aimed to compare the dentoalveolar and skeletal changes resulting from treatment using two popular functional appliances: the Bite-Jumping Appliance (BJA) and the Twin-Block Appliance (TBA). STUDY DESIGN: This study is designed as a parallel-group, randomized controlled trial. MATERIALS AND METHODS: Patients were screened from the patients who were seeking treatment at the Department of Orthodontics, Al-Baath University. Eligibility criteria included skeletal Class II division 1 malocclusion resulting from the retrusion of the mandible. A computer-generated randomization list was used to randomly divide the patients into two equal groups to be treated with either the BJA or the TBA. Blinding was applicable for outcome assessment only. Forty-four patients (22 male and 22 female) aged 10.2-13.5 years were randomized in a 1:1 ratio to either the BJA or the TBA groups, and four patients were lost to follow-up (two from each group). Lateral cephalometric radiographs were obtained before treatment and after 12 months of active appliance therapy. Inter-group differences were evaluated with two-sample t-tests, and intra-group differences were assessed with paired-sample t-tests at the P <0.05 level. RESULTS: Forty patients (20 in each group) were available for the statistical analysis. Baseline characteristics were similar between groups. Similar changes were observed in the sagittal plane, including a significant increase in the SNB angle. No significant changes were observed in the maxilla. The lower incisors were significantly proclined, and the upper incisors significantly retruded. In the vertical plane, BJA induced mandibular clockwise rotation, and the SN:MP angle increased by 2.14 +/- 2.97 degrees (P = 0.002). Conversely, no significant changes took place in this angle in the TBA group 0.75 +/- 2.37 degrees (P = 0.096). Similarly, Jarabak ratio decreased significantly in the BJA group by -1.78 +/- 0.85% (P = 0.002) and increased significantly in the TBA group by 1.26 +/- 0.76% (P = 0.032), with significant differences between the two groups (P </= 0.001). No serious harm was observed. LIMITATIONS: A limitation of this research is a lack of an untreated control group. However, the resulting differences between the two groups can be attributed to the appliance differences, which fulfil the aim of the current research. CONCLUSIONS: Each of the two appliances is recommended for the functional treatment of skeletal Class II malocclusion resulting from the retrusion of the mandible. The BJA is recommended when clockwise rotation is desired, whereas the TBA is recommended to inhibit vertical development. REGISTRATION: This trial was registered at the Department of Orthodontics, Al-Baath University, Number 16, on 6/25/2012. PROTOCOL: The protocol was not published before trial commencement. FUNDING: No funding or conflict of interest to be declared.