Self-applied fluoride gels

Despite safety warnings dating back to the early 1980s (Ekstrand 1981), dentists are still prescribing fluoride gels for home use by patients at high risk of caries, including individuals with reduced salivary flow as a result of of cancer treatment. Patients prescribed self-applied fluoride gels should be aware that this method of fluoride delivery is particularly risky. Although self-applied fluoride gels generally contain less fluoride (5 mg of fluoride per milliliter) than professionally applied gels (12.3 mg/mL), the process of self-applying the gels can result in significantly more ingestion of the product. In one published case report, a 50-year old cancer patient developed fluoride poisoning, as evident by “gastric symptoms, difficulty in swallowing, leg muscle soreness and knee joint soreness.” (Eichmiller 2005). The dentists who authored of the report stated that:

“The combination of gastric problems, difficulty in swallowing, leg muscle pain, and pain in the knee and hip joints is a key indicator of fluoride toxicity, and patients using high-concentration home fluoride treatments should be monitored for these symptoms.”
SOURCE: Eichmiller FC, et al. (2005). Controlling the fluoride dosage in a patient with compromised salivary function. Journal of the American Dental Association 136(1):67-70.

In other research, scientists have found that ingesting small quantities of self-applied gels can significantly erode the gastric mucosa in the stomach (Spak 1990). Not only can self-applied fluoride gels cause systemic fluoride toxicity, there is a notable absence of evidence demonstrating their efficacy. As noted in one review:

“Relatively little information is available to document the efficacy of these self-applied fluoride gels. . . [J]ustification for the use of these self-applied fluoride gels is tenuous. . . . On the other hand, there is evidence to suggest that their use by preschool-age children increases the risk of developing dental fluorosis.”
SOURCE: Stookey GK. (1994). Review of fluorosis risk of self-applied topical fluorides: dentifrices, mouthrinses and gels. Community Dentistry & Oral Epidemiology 22(3):181-6.

Fluoride Varnishes

Fluoride varnishes are designed to bond fluoride to the surface of the teeth for days or weeks at a time. Most fluoride varnishes contain 5% sodium fluoride, or 22.6 milligrams of fluoride for each milliliter of varnish that is applied. While this is twice the concentration used in professionally applied fluoride gels (12.3 mg per milliliter), less varnish is used per treatment.  With fluoride gels, dentists generally apply about 4 to 8 mL of gel per treatment (48 to 96 mg of fluoride). With varnishes, dentists apply about 0.5 to 1.0 mL of varnish (11.3 to 22.6 mg of fluoride). Fluoride varnishes, therefore, introduce less fluoride into the mouth than fluoride gels. Moreover, because of their slow-release quality, varnish does not cause the same severe spike in blood fluoride levels that gels create. Nevertheless, varnishes do expose a child to significant levels of fluoride, as all of the fluoride that is introduced into the mouth with a varnish will be swallowed.

Fluoridated Salt

The use of fluoridated salt is becoming increasingly widespread across the globe. While the US & Canada do not yet have salt fluoridation programs, it is currently estimated that more people in the world are exposed to fluoridated salt than fluoridated water. Thus, this source of fluoride exposure is becoming increasingly important and insidious. Fluoridated salt usually contains about 250 ppm fluoride, which would result in a daily intake of 2.5 mg of fluoride per day for people consuming 10 grams of salt. A number of South American Countries allow salt fluoridation programs, including Bolivia, Columbia, Costa Rica, Dominican Republic, Honduras, Jamaica, Nicaragua, Panama, and Venezuela. A number of European countries also allow salt fluoridation, including: Austria, the Czech Republic, France, Germany, Slovakia, Spain, and Switzerland. As shown in the following table, however, the usage rates vary greatly in these countries.

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