Water Fluoridation and Dental Caries Prevention Globally: A Systematic Review and Meta-Analysis

Fluoridation of community water supplies constitutes one of the most effective public health interventions for preventing dental caries. In recent years, questions have been raised about its effectiveness and safety. This study aims to systematically review and summarize the existing evidence on community water fluoridation (CWF) and dental caries in permanent and deciduous teeth. Five databases and 3 gray databases were searched for relevant studies. Paired reviewers independently screened the studies, extracted data, and assessed their methodological quality. Standard mean differences (SMDs) for dmf(s)/DMFT(S) (decayed, missing, and filled teeth/surface) and odds ratios (ORs) for caries prevalence were measured between exposure or not to CFW for deciduous and permanent teeth. Subgroup analysis was performed to explore whether the study design, continent, or decade of publication changed the point estimates. Seventy-four studies were included in the qualitative analysis: 57 cross-sectional, 13 before-and-after, and 4 cohort studies. Thirty-two studies provided sufficient data for meta-analyses. The overall SMD of DMFT and dmf in those exposed to CWF compared with unexposed were −0.32 (95% confidence interval [CI]: −0.48 to −0.17, I 2 = 96%, P < 0.01) and −0.30 (95% CI: −0.39 to −0.21, I 2 = 88%, P < 0.01), respectively. The prevalence of caries was smaller in those exposed to CWF for both the permanent (OR = 0.52, 95% CI: 0.43 to 0.63) and deciduous (OR = 0.60, 95% CI: 0.48 to 0.76) dentitions. Study design, continent, or decade of publication satisfactorily explained the heterogeneity between studies. Communities where water was fluoridated experienced less caries and differences expressed in terms of SMD and prevalence (OR) where of high magnitude, both in children and in adults. The results of the meta-analyses revealed significant differences in caries experience and prevalence in favor of CWF, which represents an effective and comprehensive public health intervention for caries prevention, especially in the primary dentition. Knowledge Transfer Statement: Based on the published literature, the results of this study show that fluoridation of community water supplies is still an effective public health intervention to prevent dental caries, both in children and adults, despite the widespread availability of fluoride-containing dental products, especially toothpaste. This result adds to the existing evidence to support its incorporation into public oral health policies.