Overview
Fluoride gel is a professional, high-concentrated topical fluoride agent, containing from 2,425 to 12,500 ppm F (usually around 10,000 ppm F) based on sodium fluoride, acidulated phosphate fluoride or amine fluoride. Their effect is based on the reaction of high concentration fluoride with the tooth, forming a fluoride reservoir (calcium fluoride-like precipitate) on the surface of teeth that will slowly release fluoride overtime. The gels are flavoured but contain no abrasive cleaning agents or preservatives.
Use and Application
Fluoride gels are mainly intended for professional application using plastic/disposable trays or cotton swabs, 2-4 times per year. After 1 min, the excess of the gel is removed. The gel application in trays for 1 minute may be unpleasant for some patients. In some countries, fluoride gels may be prescribed by a dentist as part of a preventive program, and applied by the patient with the aid of a toothbrush once per week or month.
Effectiveness and Efficacy
Evidence from systematic reviews suggests an average prevented fraction of 28% in children and adolescents compared with placebo or no treatment [1]. There are few reports on the effectiveness of fluoride gel in the primary dentition and there is insufficient evidence to conclude whether or not there is difference in the efficacy of sodium fluoride vs. acidulated phosphate fluoride gels.
Safety
Fluoride gels are safe when used according to instructions. The main caution is on the amount used, especially when trays are used for application, to minimize ingestion. Fluoride gel application using trays is not recommended for children younger than six years. Nausea and vomiting can occur as a result of fluoride toxicity caused by excessive ingestion of the gel if not properly controlled. Dental professionals should be aware of the fluoride concentration in the applied product if they need to calculate for toxicity doses.
Cost Effectiveness
In parallel with professional fluoride varnishes, the use of fluoride gel in trays is a significantly more cost-effective measure amongst high-risk populations than in low-risk groups [2]. Studies on cost-effectiveness in adults are lacking.
Recommendations
Professional or self-applied fluoride gels should be considered as a professional fluoride option to increase fluoride exposure to individuals older than six years and assessed with increased caries risk.
Key Further Reading
1- Cochrane reviews of randomized trials of fluoride therapies for preventing dental caries.
Marinho VC. Cochrane reviews of randomized trials of fluoride therapies for preventing dental caries. Eur Arch Paediatr Dent 2009;10:183-91.
2- Randomised controlled trial of the efficacy of a high-fluoride gel self-applied by toothbrushing in children at high caries risk.
Stokes E, Ashcroft A, Burnside G, Mohindra T, Pine CM. Randomised controlled trial of the efficacy of a high-fluoride gel self-applied by toothbrushing in children at high caries risk. Caries Res 2011;45:475-85.

Guidance Document
ACFF Members can download the download the full reference document for Fluoride Gels.