Seventeen studies were included: six randomised controlled trials (n=381) and 11 controlled clinical trials (n=640). Six were classed as low risk of bias, seven as medium risk and four as high risk of bias. All studies were analysed on a per-protocol basis.
Four studies reported subjective pain after initial placement of the brackets, at different time intervals. There were no statistically significant differences between self-ligating brackets and conventional brackets at four hours, 24 hours, 72 hours and seven days (three low-risk studies).
Other outcomes such as efficiency of initial orthodontic alignment, bond failure rate, plaque retention and periodontal health, torque expression and arch dimensional change, orthodontic space closure and apical root resorption were reported in the review. Some studies failed to report standard deviations and/or were at high risk of bias so meta-analysis was not possible.