DATA SOURCES: Studies were identified using searches with Medline, the Cochrane Library and Google Scholar. STUDY SELECTION: Studies were screened independently and were included if they evaluated the effect of one or more chewing gums containing at least one polyol (xylitol, sorbitol, mannitol or maltitol) on caries development, provided they supplied original data generated by means of a comparative design (experimental or observational) and were published in English. Studies were excluded if only an abstract was available or they described only the pharmacodynamic or pharmacokinetic properties of polyols or did not include a no-treatment arm in the study. Randomised trial quality was assessed using the Jadad scale, and the US Preventive Services Task Force criteria to grade the internal validity of individual nonrandomised studies. DATA EXTRACTION AND SYNTHESIS: Data were extracted independently with only the final outcomes of a study being recorded. It was decided that surface rather than tooth level data would be recorded. Incremental caries was converted to prevented fraction (PF; the proportional reduction in dental caries in experimental groups relative to control groups) for meta-analysis. The studies were grouped according to type of polyol and a separate meta-analysis performed. Data were pooled using both a random and a fixed-effects model and heterogeneity assessed using I2. RESULTS: Of 231 articles identified 25 studies were initially selected with 19 being included in the review [six randomised controlled trials (RCT) of which four were cluster RCT, nine controlled clinical trials (CCT) and four cohort studies]. Two RCT had a Jadad score of three or higher. The mean preventive fraction for the four main gum types are shown in the table 1, results of all except the sorbitol -mannitol blend were statistically significant. Sensitivity analyses confirmed the robustness of the findings. CONCLUSIONS: Although research gaps exist, particularly on optimal dosing and relative polyol efficacy, there is consistent evidence to support the use of xylitol- and sorbitol-containing chewing gum as part of normal oral hygiene to prevent dental caries.