Data sources Six electronic databases/registries including MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, Embase, SCOPUS, Web of Science) were searched up to 1 January 2018. Additionally, ongoing and unpublished trials were sought as well as a manual search also to January 2018. No restrictions on language or publication date were set.Study selection Only randomised controlled trials (RCTs) assessing active orthodontic patients that received any type of reminder or not, and the impact of the reminder on periodontal parameters and/or rate of attendance, were included.Data extraction and synthesis Two reviewers abstracted data independently after a customised data extraction form was piloted. Risk of bias (RoB) was assessed using the Cochrane collaboration risk of bias tool. The results for periodontal parameters were synthesised (random effects meta-analysis) as mean difference or standardised mean difference with 95% CIs. Effects on attendance rate and frequency of white spots were synthesised (random effects meta-analysis) using relative risks (RR) with their 95% CIs where possible.Results Fourteen parallel-group RCTs involving 2,078 participants were included with 1,059 participants in the meta-analysis). Studies in different parts of the world were included. Different reminder systems were identified (SMS, mail, automatic phone calls, mobile apps). Outcomes considered were: plaque scores (ten RCTs), gingival scores (six RCTs), appointment attendance (five RCTs), white spot development (four RCTs), and other outcomes (one RCT). Three studies were judged at high RoB, six were unclear and five were at low RoB (not included in the meta-analysis). Plaque indices measured over a short time period were significantly affected (SMD .38; 95%CI: -0.65 to -0.10), and over longer term .Patients receiving reminders (SMD -1.51; 95%CI: -2.72 to -0.30)were less likely to miss appointments (RR 0.39; 95%CI: 0.22 to 0.70) or develop white spots (RR 0.45; 95%CI: 0.31 to 0.65) .Conclusions In general terms there is moderate-to-high quality of evidence that reminders have a positive effect on oral hygiene, improved appointment adherence and the reduction of white spot development.