Fluoride in Preventive Dentistry: Topical vs. Systemic Applications

Study Notes

Fluoridation of water supplies is the most effective public health measure for preventing dental caries, according to the WHO (2005).
The controlled addition of fluoride compounds to the water supply aims to bring its concentration to an optimal level to prevent caries.
The optimal level of fluoride in water is 0.7-1.2 milligrams (mg) of fluoride ion per liter, which is equivalent to 1 ppm (part per million).
The US set a level of 0.7 ppm in 2015.
The optimal level of 1 ppm reduces caries by 50%.
The recommended level of fluoride varies depending on climate, with 0.7 ppm suggested for hot climates and 1.2 ppm for cold climates.

Topical fluorides strengthen teeth already present in the mouth, making them more caries-resistant.
Self-applied topical fluorides include toothpastes, gels, and mouth rinses, which can reduce caries by 27% in permanent teeth and 20% in primary teeth.
Professionally applied topical fluorides include higher-strength rinses, gels, and foams, fluoride varnishes, and silver diamine fluoride.
Fluoride varnishes can reduce caries by 37% in primary teeth and 43% in permanent teeth.
Gels can reduce caries by 20% in primary teeth and 28-38% in permanent teeth.

The application schedule for SDF is uncertain, but the recommendation is to monitor caries lesion arrest after 2-4 weeks and consider reapplication.
The effectiveness of one-time SDF application in arresting dental caries lesions ranges from 47% to 90%.
Increasing the frequency of application can increase the caries arrest rate.
A side effect of SDF is black staining of carious lesions and soft tissue.

Fluorosis is a potential risk of fluoride use, occurring when excess levels of fluoride are ingested during tooth development.
The degree of fluorosis depends on the total dose of fluoride from all sources, timing, and duration of fluoride exposure.
Fluorosis varies in appearance from white striations to stained pitting of enamel.
Fluorosis cannot occur once enamel formation is complete and the teeth have erupted, regardless of intake.
To reduce the risk of fluorosis, parents of children younger than 6 years should supervise toothbrushing, and fluoride supplements and mouth rinses should be limited to children.

Excessive use and intake of fluoride can lead to fluorosis.
The optimal dose of fluoride is 0.05-0.07 mg F/kg.
The certainly lethal dose (CLD) is 16-32 mg F/kg, and the probably toxic dose (PTD) is 5 mg F/kg.
Treatment of fluoride toxicity depends on the suspected ingestion amount, with hospital admission and administration of products that slow absorption required for higher doses.

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