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How to Discuss Longevity of Fluoride Varnish

How should I answer a patient who wants to know how long the benefits of fluoride varnish last?

How should I answer a patient who wants to know how long the benefits of fluoride varnish last?

Fluoride varnish has become a widely utilized, professional topical application for treating dentinal hypersensitivity and preventing caries. While fluoride varnish has United States Food and Drug Administration approval for treating sensitivity, caries prevention is an off-label use. When answering this question for our patients, we need to review the mechanism of action for topical fluorides and the current evidence in the literature.

The three main benefits of topical fluoride application are: decreasing the demineralization of enamel, increasing the remineralization of enamel, and inhibiting bacterial activity.1 Many manufacturers are adding minerals, such as calcium and phosphate, to their fluoride varnish formulations with the thought that they may increase bioavailability in the oral cavity, saliva, and biofilm, and, in turn, increase fluoride release and enhance the remineralization process.2

In the 2013 American Dental Association (ADA) executive summary of the updated clinical recommendations and supporting systemic review on topical fluoride for caries prevention, the panel authors discuss recommendations for professionally applied fluorides, which included prescription-strength and home-use topical fluorides.3 The full report can be accessed at:

For fluoride varnish specifically, the panel recommended the application of 5% sodium fluoride at least every 3 months to 6 months for patients with elevated caries risk, which encompassed varying age groups (younger than 6, ages 6 to 18, those older than 18, and adults at risk of root caries). The report did not distinguish between moderate caries risk and high caries risk, but stated that patients at low caries risk may not need additional topical fluoride supplementation.3 However, fluoride varnish with mineral enhancements were not reviewed in the 2013 ADA report. The American Academy of Pediatric Dentistry also recommends that children at high caries risk receive a fluoride varnish application every 3 months to 6 months.4

Before applying fluoride varnish, clinicians should review the post-treatment instructions with the patient. Generally, patients should not eat or drink anything that is hot, sticky, hard, crunchy, or alcoholic for 4 hours to 6 hours after placement. By following these instructions, the sticky rosin (adhesive derived from pine trees) can adhere longer to the dentition until it is later brushed off or removed. Research studies have demonstrated that fluoride varnish has “long-lasting efficacy” in caries prevention.5,6 An advantage of fluoride varnish application is that it can be placed directly on exposed root surfaces or sensitive areas of the enamel.

For patients with elevated caries risk, I would suggest following the ADA guidelines, which recommend that fluoride varnish be placed at least every 3 months to 6 months. It has yet to be determined in the research if more frequent applications of fluoride varnish  provide additional benefits. In vivo  (using human subjects) research is needed to investigate the efficacy and longevity of fluoride varnish formulations with mineral enhancements, which will help to guide future clinical recommendations.2,7–9

Clinicians should consider evidence-based research, clinical experience, patients’ unmet needs and preferences, and patients’ caries risk levels in their decision making.3 While there is no specific timeframe as to how long fluoride varnish may last, we know from the existing literature that it offers many benefits with more frequent and consistent intervals of application, especially for those populations most vulnerable to dental caries.


  1. Featherstone, JD. The science and practice of caries prevention. J Am Dent Assoc. 2000;131:887–899.
  2. Shen P, Bagheri R, Walker GD, et al. Effect of calcium phosphate addition to fluoride containing dental varnishes on enamel mineralization. Aust Dent J. 2016;61:357–365.
  3. Weyant RJ, Tracy SL, Anselmo TT, Beltran-Aguilar ED. American Dental Association Council on Scientific Affairs Expert Panel on Topical Fluoride Caries Preventive Agents. Topical fluoride for caries prevention: executive summary of the updated clinical recommendations and supporting systematic review. J Am Dent Assoc. 2013;144:1279–1291.
  4. American Academy of Pediatric Dentistry. Fluoride Therapy. In: The Reference Manual of Pediatric Dentistry. Chicago: American Academy of Pediatric Dentistry; 2018:262–265.
  5. Carey CM. Focus on fluorides: update on the use of fluoride for the prevention of dental caries. J Evid Based Dent Pract. 2014;(14 Suppl):95–102.
  6. Arruda AO, Senthamarai Kannan R, Ingelhart MR, Rezende CT, Sohn W. Effect of 5% varnish applications on caries among school children in rural brazil: a randomized controlled trial. Community Dent Oral Epidemiol. 2012;40:267–276.
  7. Majithia U, Venkataraghavan K, Choudary P, Trivedi K, Shah S, Virda M. Comparative Evaluation of application of different fluoride varnishes on artificial early enamel lesion: An in vitro study. Indian J Dent Res. 2016;27:521–527.
  8. Al Dehailan L, Martinez-Mier EA, Lippert F. The effect of fluoride varnishes on caries lesions: an in vitro investigation. Clin Oral Invest. 2016;20:1655–1662.
  9. Al Dehailan L, Lippert F, Gonzalez-Cabezas C, Eckert GJ, Martinez-Mier EA. Fluoride concentration in saliva and biofilm fluid following the application of three fluoride varnishes. J Dent. 2017;60:87–93.
The Ask the Expert column features answers to your most pressing clinical questions provided by Dimensions of Dental Hygiene’s online panel of key opinion leaders, including: Jacqueline J. Freudenthal, RDH, MHE, on anesthesia; Nancy K. Mann, RDH, MSEd, on cultural competency; Claudia Turcotte, CDA, RDH, MSDH, MSOSH, on ergonomics; Van B. Haywood, DMD, and Erin S. Boyleston, RDH, MS, on esthetic dentistry; Michele Carr, RDH, MA, on ethics and risk management; Erin Relich, RDH, BSDH, MSA ,on fluoride use; Kandis V. Garland, RDH, MS, on infection control; Mary Kaye Scaramucci, RDH, MS, on instrument sharpen­ing; Kathleen O. Hodges, RDH, MS, on instrumentation; Karen Davis, RDH, BSDH, on insurance coding; Cynthia Stegeman, EdD, RDH, RD, LD, CDE, on nutrition; Olga A.C. Ibsen, RDH, MS, on oral pathology; Martha McComas, RDH, MS, on patient education; Michael W. Roberts, DDS, MScD, on pediatric dentistry; Timothy J. Hempton, DDS, on periodontal therapy; Ann Eshenaur Spolarich, RDH, PhD, on pharmacology; and Caren M. Barnes, RDH, MS, on polishing.Log on to​​asktheexpert to submit your question.

From Dimensions of Dental Hygiene. March 2021;19(3):46.

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