Burhan 2015.

Methods	Location: Damascus, Syria Number of centres: 1. Al Baath University, Syria Recruitment period: registered patients in pending records Funding source: not specified Trial design: parallel group RCT
Participants	Inclusion criteria: skeletal Class II division 1 malocclusion resulting from the retrusion of the mandible (SNB angle < 78°); convex facial profile; ANB angle > 4°; good mouth health; no previous orthodontic treatments; pubertal growth spurt peak at the beginning of the treatment, which was assessed using hand–wrist radiographs according to the Fishman method Exclusion criteria: none specified Age at baseline: Bite Jumping Appliance group 11.5 years (SD 1.0), Twin Block 11.8 years (SD 0.9) Number randomised: 44 (22 in each group) Number evaluated: 40
Interventions	Gp A (n = 20): Bite jumping appliance – removable functional appliance Gp B (n = 20): Twin Block appliance – removable functional appliance
Outcomes	Using cephalometric radiograms, the dentoalveolar and skeletal effects resulting from both appliances were detected.
Notes	Duration of active treatment – 12 months + recruited period (not reported) Sample size: to determine the appropriate sample size, the Minitab software was used with two‐sample t‐tests, a selected study power of 80%, a significance level of 0.05, and a detected difference of 1°. The used standard deviation (SD) of 1.09° was based on a pilot study of 10 cases (five in each group). The appropriate sample size was 20 patients in each group. This number was increased to 22 participants to compensate for the potential dropouts.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer‐generated randomisation list was used to randomly divide the patients into two equal groups.
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding of assessment was performed by (ASB) coding names of patients on pre‐ and post‐treatment cephalograms, and tracing and measurements were performed by (FRN), so that the group each participant belonged to was unknown when the records were evaluated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	BJA group ‐ recruited 22, completed 20 (loss 10%) TB group ‐ recruited 22, completed 20 (loss 10%) Reasons for discontinuation: BJA group ‐ failed to return for follow‐up appointments (n = 2) TB group ‐ failed to return for follow up appointments (n = 1); uncooperative patients (n = 1)
Selective reporting (reporting bias)	Low risk	All variables reported
Other bias	Low risk	No other source of bias identified