Data sourcesMedline, Embase, Cochrane CENTRAL and OpenGREY databases without language restriction until March 2016 plus manual searching of four specific journals and consideration of reference lists.Study selectionStudies evaluating different methods of periodontal treatment in Down syndrome patients measuring at least two periodontal parameters at different periods of assessment. Titles, abstracts and full texts were considered by two independent reviewers and a third where discussion did not reach consensus. Randomised controlled trials were evaluated using the Cochrane risk of bias tool. The observational studies were evaluated using an adapted version of the Newcastle-Ottawa Scale.Data extraction and synthesisData extraction was carried out independently by two reviewers and organised into evidence tables. No meta-analysis was undertaken, however a narrative synthesis was presented.ResultsNine studies met the inclusion criteria; four longitudinal studies, one prospective case series and four clinical trials which included two cross-over studies and a controlled trial. The studies showed marked heterogeneity in terms of methodology, intervention and outcome measures. All studies, however, included assessment of different plaque and gingival indices.Three studies investigated outcomes after scaling and root planing, one of which compared surgical and non-surgical approaches. Periodontal pockets of 1-3 mm were statistically significantly improved with non-surgical treatment in comparison with pockets greater than 4 mm which showed greater reduction with surgical treatment. Six studies investigated different forms and uses of chlorhexidine, three of which investigated its use as an adjuvant to mechanical debridement and one which also included plaque disclosing as an intervention. Chlorhexidine was shown to be most effective when used daily as a 1% gel for toothbrushing. The use of a plaque disclosing tablet and fluoridated tooth paste, however, showed further improved outcomes with regards to plaque control.ConclusionsEight of the nine studies included showed improvement in the primary outcomes of improved plaque and gingival bleeding indices. Professional intervention and periodontal maintenance significantly reduced plaque and gingival indices, irrespective of the treatment performed. Increased frequency of interventions was associated with better outcomes, especially in younger age groups.