Purpose: This patient-level meta-analysis aimed to evaluate the efficacy of rapid palatal expansion to treat nocturnal enuresis among children.

Materials and Method: A sensitive search of electronic databases of PubMed (since 1966), SCOPUS (containing EMBASE, since 1980), Cochrane Central Register of Controlled Trials, CINAHL and EBSCO till Jan 2014 was performed. A set of regular terms was used for searching in data banks except for PubMed, for which medical subject headings (MeSH) keywords were used. Children aged at least six years old at the time of recruitment of either gender who underwent rapid palatal expansion and had attempted any type of pharmacotherapy prior to orthodontic intervention were included. 

  Results: Six non-randomized clinical trials were found relevant, of which five studies had no control group. Eighty children were investigated with the mean age of 118 (28.12) months ranged from 74 to 185 months. The median time to become completely dry was 2.87 months [confidence interval (CI) 95% 2.07-2.93 months]. After one year, the average rate of becoming complete dry was 31%. The presence of posterior cross bite [relative risk (RR): 0.31, CI 95%: 0.12-0.79] and signs of upper respiratory obstruction during sleep (RR: 5.1, CI 95%: 1.44-18.04) significantly decreased and increased the chance of improvement, respectively. Meanwhile, the other predictors did not significantly predict the outcome after simultaneous adjustment in Cox regression model. 

  Conclusion: Rapid palatal expansion may be considered when other treatment modalities have failed. The 31% rate of cure is promising when compared to the spontaneous cure rate. Though, high-level evidence from the rigorous randomized controlled trials is scarce (Level of evidence: C).