Water fluoridation for the prevention of dental caries.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of prospective controlled studies
PubMed 26092033 · doi:10.1002/14651858.CD010856.pub2
What was done
The authors conducted a systematic review and meta-analysis of prospective studies with concurrent controls evaluating the effects of artificial or natural water fluoridation versus non-fluoridated water on dental caries across at least two time points. They also included controlled studies assessing dental fluorosis across varying water fluoride concentrations. Searches were conducted through February 19, 2015 across multiple electronic databases without language restrictions. Risk of bias was assessed with an adapted Cochrane tool. Quantitative synthesis evaluated differences in mean change scores for decayed, missing, and filled teeth in deciduous (dmft) and permanent (DMFT) dentition, proportions of caries-free individuals, and dental fluorosis risk.
What was found
A total of 155 studies met inclusion criteria, with 107 contributing data for quantitative synthesis: - Caries reduction: Initiation of water fluoridation resulted in a reduction in dmft of 1.81 (95% CI 1.31 to 2.31; 9 studies, 44,268 participants; 35% relative reduction vs. median control) and in DMFT of 1.16 (95% CI 0.72 to 1.61; 10 studies, 78,764 participants; 26% relative reduction). All pooled studies were at high risk of bias. - Caries-free proportion: Increased by 15% in deciduous dentition (95% CI 11% to 19%; 10 studies, 39,966 participants) and by 14% in permanent dentition (95% CI 5% to 23%; 8 studies, 53,538 participants). - Fluorosis risk: At 0.7 ppm fluoride, the estimated percentage with fluorosis of aesthetic concern was 12% (95% CI 8% to 17%; 40 studies, 59,630 participants), and any level of fluorosis was 40% (95% CI 35% to 44%; 90 studies, 180,530 participants). - Missing evidence: 71% of studies were conducted prior to 1975 (before widespread fluoride toothpaste use). No eligible studies evaluated caries prevention in adults, effects across socioeconomic status disparities, or the impact of stopping water fluoridation.
Why it matters
While water fluoridation historically reduced childhood dental caries, contemporary applicability is uncertain because modern populations have widespread exposure to other fluoride sources, and water fluoridation increases the risk of dental fluorosis.
Limits
The vast majority of included studies carried a high risk of bias (over 97% for fluorosis; all pooled caries severity studies) with substantial between-study heterogeneity. Most data predate 1975, limiting generalizability to modern settings. No eligible studies examined adult populations, cessation of fluoridation, or socioeconomic disparities.
Cited by
- context Approximately 80% of the United States population receives fluoridated municipal water, adding more fluoride to water than the rest of the world combined.