Effect of artificial community water fluoridation on dental health. An evidence review

This systematic review collates the evidence on the positive and negative effects of artificial community water fluoridation (CWF) on dental caries and fluorosis between 1948 and 2023. In addition, the review attempts to establish if there are dose response relationships between CWF levels (from 0.5ppm to 1.2ppm) and dental caries, or between CWF levels and dental fluorosis. Finally, the use of other sources of topical fluoride in combination with CWF by children aged under 6 years is investigated.

The certainty of the evidence for all dental caries outcomes and the intervention CWF is low or very low. The majority of dental caries outcomes in primary dentition indicated a reduction in cavitated caries that favoured CWF areas over the fluoride deficient areas. The findings for permanent dentition outcomes indicated a reduction in cavitated caries for all except one outcome and the reduction favoured the CWF areas over the fluoride deficient areas.

The certainty of evidence for the prevalence of fluorosis across countries with CWF is very low. The prevalence of dental fluorosis in permanent teeth of 10‒15-year-old children living in CWF areas, using Dean’s Index of Fluorosis, ranged from 1.3% to 47.7%. The prevalence of dental fluorosis in permanent teeth of schoolchildren and young people living in CWF areas, using the Tooth Surface Index of Fluorosis, ranged from 18.3% to 69.2%, and was using the Thylstrup and Fejerskov Index. The vast majority of cases had very mild or mild dental fluorosis. The prevalence of dental fluorosis increased over time in Brazil, Ireland, and the USA, and this increase was observed both in areas with and without CWF. This meta-analysis indicated that children living in CWF areas had three times higher adjusted odds of dental fluorosis than children living in fluoride-deficient areas.

Eight studies in CWF areas identified a relationship between oral hygiene practices related to the use or misuse of fluoride toothpaste commenced during the first 6 years of life and dental fluorosis, indicating low certainty evidence that there may be a relationship between exposure to fluoride toothpaste and how it is used, and the outcome of dental fluorosis in permanent teeth.
The association between the use of fluoride mouth rinses together with CWF, when children living in areas with CWF were aged under 6 years, and dental fluorosis is mixed and the evidence is very low certainty.