Data sourcesCochrane Oral Health's Trials Register, Cochrane Central Register of Controlled Trials, Medline Ovid and Embase Ovid (up to February 2017); ongoing clinical trials were searched in clinicaltrials.gov as well as the World Health Organization International Clinical Trials Registry. Reference lists of included studies and relevant systematic reviews were searched. No restrictions were placed on the language or date of publication and study authors were contacted when necessary.Study selectionRandomised and quasi-randomised controlled trials assessing open and closed surgical exposures in palatally displaced canines with no restriction on age, presenting malocclusion or type of orthodontic treatment. Unilaterally and bilaterally displaced canines were included in the review. The primary outcomes considered were sufficient eruption of the canine to allow orthodontic alignment without requiring additional surgery, post surgical complications and aesthetics.Data extraction and synthesisTwo authors independently screened titles and abstracts of all studies identified through the search and reviewed full articles against established inclusion criteria. Any disagreements between the authors were resolved by consensus or by consulting an expert. Risk of bias assessment was done using Cochrane Collaboration's tool and study authors were contacted for missing information. Dichotomous outcomes (success of surgery - yes or no) were expressed as risk ratio and 95% CI. Continuous outcomes (pain on VAS scale) were expressed as mean differences (MD) or standardised mean differences (if different scales were used).ResultsA total of three studies (six articles) representing 146 participants were included in the SR. One was an RCT while the other two were quasi-RCTs. With regards to successful eruption, there was no evidence of a difference between the open and closed groups (RR 0.99, 95% CI 0.93-1.06, P = 0.79). Other primary measures (including surgical complications or aesthetics) or secondary measures were either reported in just one trial or used different measures, so pooling of data was not possible.ConclusionsLimited available evidence suggests surgical exposure of palatally displaced canines is successful in bringing canines into alignment. However, data do not support one technique over the other (closed vs open). One trial was at low risk of bias while the others were at high risk of bias. This adds to the uncertainty of the conclusions.