The use of fluoride as caries prophylactic does not pose a health risk

Caries-prophylactic use of fluoride is regarded as safe.

Aida Mulic               Jon E. Dahl
Senior Scientist  Managing Director

Fluoride skepticism “FluUro”. The use of fluoride as caries prophylactic does not pose a health risk, Professor Jon E. Dahl, stated at the annual convention for the Norwegian dental association. He discussed the kinetics and the general toxicity of applied fluoride. A negligible amount of fluoride is absorbed through the oral mucosa; however, about 90% of a swallowed dose is taken up in the blood and distributed. Between 30 and 50% of the absorbed fluoride is deposited in the teeth during their formation and in the bones. Fluoride that is not taken up in the hard tissues is secreted by the kidney (40-60%) or the gut (about 10%).

Acute toxicity may occur on intake of more than 5 mg of fluoride per kg body weight. (Table 1). This corresponds to such a large dose of that accidental poisoning can be ruled out. Skeletal fluorosis is a bone disease caused by excessive accumulation of fluoride in the bones. It is seen in countries where there is natural high level of fluoride in the drinking water, such as China and India, and it is not relevant for the Nordic countries. Studies from areas with water fluoridation do not provide evidence that the daily uptake of fluorides presents any health hazards.

Table 1: Examples of added amount that trigger acute toxicity reactions in children and adults

AgeWeightAmount toothpaste
(1450 ppm F-) 75 mL
Tablets (0,5 mg)
1 yr10 kg1/2 tube100
5 yrs20 kg1 tube200
12 yrs30 kg1,5 tubes300
Adult70 kg3 tubes700
High risk patients need fluoride supplement.

The “FluUro” session at the convention concluded with senior scientist Aida Mulic who discussed the recommended use of fluorides. According to Mulic, the effect of local fluoride treatment depends on concentration of fluoride, length of time of application, frequency of treatment, the pH of the fluoride product, and the presence of metal fluorides (tin or titanium) used in combination with NaF.

Table 2: Overview of available fluorid prophylactics and their concentration of F- (ppm)

Fluorid prophylacticF-(ppm)
Daily fluorid rinse (0,2% NaF)920
Duraphat® toothpaste5000
Fluor Protector1000
Fluorid varnish 2% NaF9200
Duraphat® varnish with 5% NaF22600
Fluoride can be administered either by at home or by a professional. For the majority of children, adolescents and adults, the use of fluoride toothpaste twice daily, has the most important effect in preventing caries. However, for patients at risk such as those with dry mouth syndrome or with high caries activity, we have more to offer. (Table 2) Fluoride toothpaste with a high concentration of fluoride (e.g. Duraphat toothpaste®, 5000 ppm) has a well-documented effect. These patients are also recommended the daily use of 0.2% NaF solution and fluoride tablets.

Regarding professional treatment offered at the dental clinics, fluoride varnish (5% NaF / 2% NaF) applied at least twice a year gives caries reduction of 42-46%. Although the scientific evidence for the use of fluoride gel is limited, this treatment is recommended for a limited period for patients with severe dental caries for a limited period until the caries situation is under control.

Clinical implication: Caries prevention by daily use of fluoride containing toothpaste is documented as safe and effective.