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| Title |
Exposure to Fluoridated Water Reduces the Incidence of Dental Caries in Primary Dentition Compared to Non-Fluoridated Water |
| Clinical Question |
In children with primary dentition, does exposure to fluoridated drinking water, compared to non-fluoridated water, result in a lower incidence of dental caries? |
| Clinical Bottom Line |
For children with primary dentition, exposure to fluoridated water is associated with a lower incidence of dental caries compared to non-fluoridated water. This is supported by consistent findings from a Cochrane systematic review of global studies, a meta-analysis of observational studies in an upper-middle-income country, and a large cross-sectional study of US children. Community water fluoridation is an accessible public health measure to reduce tooth decay, especially in populations with limited access to fluoride-containing products. |
| Best Evidence |
(you may view more info by clicking on the PubMed ID link) |
| PubMed ID |
Author / Year |
Patient Group |
Study type
(level of evidence) |
| #1) 39362658 | Iheozor-Ejiofor 2024 | Children, primarily aged 0-12 yrs, across multiple countries | Systematic review of non-randomized trials | | Key results | Iheozor-Ejiofor et al. (2024) conducted a Cochrane systematic review of 157 non-randomized studies comparing tooth decay outcomes in children in communities with and without water fluoridation. Tooth decay was quantified by the following outcomes: change in the number of decay, missing, and filled primary teeth or surfaces (dmft and dmfs, respectively) and changes in the proportion of caries-free participants. Of these studies, 22 were included in the meta-analysis evaluating the effects of initiation and cessation of community water fluoridation. In studies conducted after 1975, the initiation of water fluoridation showed a slightly greater reduction in dmft than non-fluoridated groups (MD 0.24, 95% CI -0.03 to 0.52; P = 0.09, I² = 26%; 2 studies, 2908 participants), however the difference was non-significant. Studies conducted before 1975 demonstrated a significant reduction in dmft among children in fluoridated communities (MD 2.10, 95% CI 1.71 to 2.49; P < 0.001, I² = 44%; 5 studies, 5709 participants). The greater effect observed in earlier studies is likely due to the limited access to fluoride-containing products at the time. Overall, the review suggests that community water fluoridation is associated with reduced dental caries in primary dentition, with stronger effects in populations without other significant fluoride exposure. | | #2) 34564916 | Belotti 2021 | 21,289 Brazilian children aged 3-12 yrs | Meta-Analysis | | Key results | Belotti et al. (2021) completed a systematic review of 574 observational studies on dental caries incidence in Brazilian children exposed to community water fluoridation, focusing on studies conducted after 1995. Caries incidence was measured by dmft index of primary teeth and caries prevalence. Sixteen articles were included in the qualitative analysis and 10 were included in the quantitative analysis. The meta-analysis revealed a significantly lower dmft score in fluoridated communities with a mean difference of -2.28 (95% CI -2.36 to -1.30) for children aged 5-8 yrs and -1.12 (95% CI -1.93 to -0.32) for children aged 3-12 years. Additionally, caries prevalence in primary dentition (3 to 8 years) was 1.4 times lower in fluoridated areas (ln[OR] −1.42; 95% CI −1.86; −0.99). Although fluoridated toothpaste is commonly used in Brazil, the study still found a significantly lower incidence of tooth decay in primary dentition in areas with water fluoridation. | | #3) 29900806 | Slade 2018 | 10,251 U.S. children and adolescents aged 2-19 yrs | Cross-sectional study | | Key results | Slade et al. (2018) analyzed data from U.S. children aged 2 to 17 years using the 1999-2004 and 2011-2014 cycles of the National Health and Nutrition Examination Survey (NHANES). The number of decayed or filled primary tooth surfaces (dfs) was assessed for children 2 to 8 years of age, and fluoride exposure was determined by the county-level water fluoridation reporting system. In ≥75% fluoridated counties, children ages 2- to 8-years had 1.3 fewer dfs per child (95% CL 0.6, 2.2), corresponding to a 30% reduction in caries in primary dentition (95% CL 11%, 48%). When adjusting for demographics and covariates, the prevented fractions of primary dentition were 30%-39%, demonstrating an association between community water fluoridation and reduced dental caries in primary dentition. | |
| Evidence Search |
(fluoridated water OR water fluoridation OR community fluoridation) AND (dental caries OR tooth decay) AND (primary dentition OR deciduous teeth OR preschool children) |
Comments on
The Evidence |
All three studies support the benefit of community water fluoridation in reducing dental caries in primary dentition; however, each of the studies has limitations. Iheozor-Ejiofor et al. (2024) included 157 studies, but only 22 were used in the meta-analysis and of these, 10 were found to be of “critical” risk of bias, 10 to be of “serious” risk, and 1 to be of “moderate” risk due to the lack of control for socioeconomic status, a crucial confounding factor. Additionally, ten of the studies were at “serious” risk of bias due to missing data. The inclusion of older studies raises concerns about the applicability to current populations who commonly use fluoride dentifrices; however, these studies could still have relevancy to countries who lack access to fluoride products. Belotti et al. (2021) completed a systematic review focused on Brazilian children. Although fewer studies were included, confounding bias was mitigated by the inclusion of demographic and socioeconomic variables in the analysis. The findings consistently reported a protective effect of water fluoridation on dental caries; however, the study was unable to establish causality. Nevertheless, the study’s focus on an upper-middle-income country with widespread fluoride use provides a valuable context to the discussion of community water fluoridation. Slade et al. (2018) provides a large nationally representative sample of U.S. children with a cross-sectional analysis. However, the study introduced potential misclassification bias due to the classification of fluoride exposure based on county data. Children were labeled as “exposed” due to their residence in a county with at least 75% water fluoridation, thus failing to account for the 25% who lack access. Conversely, some children in the non-fluoridated counties may have been exposed to fluoride. This study also failed to account for the increasing prevalence of bottled water consumption and the 15% of U.S. children who report not drinking tap water. Despite these issues, the study had a large sample size and accounted for confounding variables lending strength to the conclusions. These studies provided a different population of study and, thus, different prospective to the discussion, and reinforce the clinical value of community water fluoridation as a strategy to reduce decay in primary dentition. |
| Applicability |
Fluoridated water has consistently been shown to provide a protective effect against dental caries in primary dentition. Although each study presented limitations, together they support the caries-preventive benefits of fluoridated water in children. These findings are particularly relevant for populations with limited access to fluoride toothpaste or regular dental care and reinforce the importance of fluoridated water as a public health measure to reduce dental caries in primary dentition. |
| Specialty/Discipline |
(Public Health) (General Dentistry) (Pediatric Dentistry) |
| Keywords |
Fluoride; children; primary caries; prevention
|
| ID# |
3578 |
| Date of submission: |
06/24/2025 |
| E-mail |
JGL0399@gmail.com |
| Author |
Johanna Lindquist |
| Co-author(s) |
Joseph Lai |
| Co-author(s) e-mail |
josephlai21@yahoo.com |
| Faculty mentor/Co-author |
Kelly C Lemke, DDS, MS |
| Faculty mentor/Co-author e-mail |
lemkek@uthscsa.edu |
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) |
post a rationale |
| None available | |
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Comments and Evidence-Based Updates on the CAT
(FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) |
post a comment |
| None available | |
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