Study designs of evaluations included in the review
Studies with a control group were eligible for inclusion if they followed up patients for at least 1 year post-active treatment. All of the included studies followed up participants for more than 5 years following the end of full active treatment.
Specific interventions included in the review
Studies of RME were eligible for inclusion if they did not use surgical or other simultaneous treatments that could influence the outcomes. The included studies compared RME with control treatments and, in one study, full fixed appliances (no further details were reported).
Participants included in the review
Inclusion criteria were not specified in terms of the participants. Where stated, the mean age of the participants in the included studies ranged from 11.8 to 13.6 years (the age range in one study was 11 to 17.4 years). Overall, 53% of the participants were female.
Outcomes assessed in the review
Studies that measured long-term (at least 1 year) transverse, anteroposterior and vertical skeletal changes using facial radiographs (anteroposterior and lateral cephalograms) were eligible for inclusion. Studies that did not report the measurement error or specify the retention period or type, or in which the appliance was modified significantly compared with the traditional RME design, appear to have been excluded.
How were decisions on the relevance of primary studies made?
Two researchers screened abstracts and titles, while three researchers independently screened full papers for inclusion. Any disagreements were resolved through discussion.