Fluoride in Preventive Dentistry: Topical vs. Systemic Applications

Community Water Fluoridation

• 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

• 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.

Silver Diamine Fluoride (SDF)

• 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

• 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.

Fluoride Toxicity

• 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.