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Fluoride supplements effective in reducing caries in permanent teeth but associated with risk of fluorosis

Steven Armstrong DDS, PhD .


Systematic Review Conclusion

There is weak and inconsistent evidence that fluoride supplements prevent dental caries in primary teeth and consistent evidence that they prevent caries in permanent teeth; however, there is an increased risk for mild-to-moderate dental fluorosis associated with the use of supplements.

Critical Summary Assessment

A thorough systematic review of 12 trials finds evidence that fluoride supplements prevent caries but may be associated with the increased risk of fluorosis.

Evidence Quality Rating

Good Evidence

Structured Abstract

Clinical Questions:

Does the use of fluoride supplements in children aged zero to 16 years 1) prevent dental caries, and 2) increase the risk of dental fluorosis in the absence of other identifiable causes?

Review Methods:

The authors comprehensive searched 4 electronic databases from 1941 to 2006 to identify studies of longitudinal randomized design with an experimental group of zero- to 16 year-olds using tablet, lozenge or drop fluoride supplements. Studies that included other sources of systemic fluoride (water, salt or milk) and nonrandomized designs were excluded. By repeating the search strategy, the authors updated a previous systematic review on the risk of fluorosis in children who ingested fluoride supplements. (1) A quality assessment was independently performed by the authors of all included studies to rate bias potential.

Main Results:

The initial search identified 911 nonduplicate reports, 85 of which the authors fully reviewed to identify 20 clinical trials that met, a priori, the inclusion criteria for caries prevention effectiveness. There were 7 trials that evaluated dosage schedules issued by the American Dental Association in 1997. Eleven reports on those trials yielded the following results: infants aged 6-months to < 3 years old experienced a 47% decrease in dmfs (1 study); children aged 3 to < 6 years experienced a zero to 43% reduction in caries in their primary teeth but none in their permanent teeth (2 studies); children aged 6 to 16 years old experienced 6% to 61% caries reduction in permanent teeth (6 studies) with one study showing a 39% reduction 4 years after supplement use was terminated. Nine studies that used other fluoride supplement regimens found no benefit in prenatal usage. However, these studies also reported caries reductions of 22% to 70% and 42% to 63% in the primary and permanent teeth, respectively, of children aged zero to 5.5 years whose supplement use started at birth. Also, children who started supplement use at the age of 12 showed no caries reduction benefit. In their quality assessments of the included studies, the authors reported that 7 trials had high rates of participant withdrawal and 5 additional studies were moderately biased due to lack of reported study details. Five additional studies evaluating risk of dental fluorosis were identified, which reconfirmed their association with fluoride supplement usage. Only qualitative analyses could be presented due to heterogeneity of subjects, outcomes and duration of follow-up.


The authors of this systematic review, found that the evidence is weak to support the effectiveness of supplements in caries prevention in primary teeth. In permanent teeth, the daily use of supplements prevents dental caries. The use of supplements during the first six years of life, especially during the first three years, is significantly associated with an increased risk for dental fluorosis.

Source of Funding:

American Dental Association


Importance and Context:

Dental caries remains the most common chronic disease in children. The ADA recommends dietary fluoride supplements for children aged 6 months to 16 years of age as a means of caries prevention if there is a suboptimal level of fluoride in their drinking water. Because these recommendations vary from those of other dental organizations and groups, the ADA commissioned this systematic review to optimize supplement indications and dosage levels for maximum caries prevention while minimizing the risk for dental fluorosis.

Strengths and Weaknesses of the Systematic Review:

The authors performed a comprehensive search of the literature to identify and select 20 reports from 12 clinical trials that addressed focused questions using accepted methods. A thorough and critical quality assessment of these trials was conducted to rate potential degree of bias. Because of study heterogeneity, the authors did not report an overall statistical result for the clinical questions addressed.

Strengths and Weaknesses of the Evidence:

Twenty reports of 12 trials were available on the effectiveness of fluoride in caries prevention. Seven trials used dosage schedules similar to the 1997 ADA recommendations; however, only 1 such trial studied children 6 months to 3 years of age. These and the remaining studies were rated as having moderate or high bias due to inadequate reporting, lack of allocation concealment, and high rates of subject withdrawal. The applicability of these results to the current U.S. population may be limited because the majority of studies were conducted before use of fluoridated dentrifices and community water fluoridation became widely prevalent. Accurately determining the risk of fluorosis from supplements is difficult due to exposure to other fluoride sources, significant variability in study designs, and variability in how fluorosis is measured.

Implications for Dental Practice:

Fluoride supplements have been shown to lower the incidence of caries in permanent teeth. There is weaker evidence of their effectiveness in primary teeth. Prescription of supplements also is associated with an increased risk for mild- to-moderate dental fluorosis. Therefore, clinicians should consider both the need for caries prevention and the risk for fluorosis on a patient-by-patient basis. The decision to prescribe a supplement should be based on the patient’s caries risk status, all known exposures to fluoride sources as well as the patient’s ability for successful compliance. The ADA will publish its recommendations in 2010, which may be viewed at REFERENCES: [1] Ismail AI, Bandekar RR. Fluoride supplements and fluorosis: a meta-analysis. Community Dent Oral Epidemiol 1999;27(1):48-56.

Critical Summary Publication Date:


These summaries are not intended to, and do not, express, imply, or summarize standards of care, but rather provide a concise reference for dentists to aid in understanding and applying evidence from the referenced systematic review in making clinically sound decisions as guided by their clinical judgment and by patient needs. American Dental Association © 2019