For prevention of dental caries, a 17-year-old boy had intermittently used a gel containing different fluoride compounds over a period of 2 years. In the last 2 months, 1 to 2 days after application, he had developed itchy perioral erythematous papules and plaques, with vesicles of the oral mucosa. The lesions healed within 1 to 2 weeks, followed by perioral scaling. Other dentifrices were tolerated well.
Patch tests were carried out with the European standard series, drug and ointment series and the 2 gels that the patient had used, diluted with 0.9% NaCl solution and tested at 1:1, 1:10, 1:100, 1:1000, and 1:10,000. At D1, D2, and D3, positive reactions (++) were observed to one of the gels at all dilutions. The ingredients of this gel, Elmex Gelee®, obtained from GABA International LLC., were then patch tested. Only component A, which was decoded as amine fluoride, showed a strongly positive reaction (++ at D1, +++ at D2 and D3). For patch testing, we used the same concentration of amine fluoride as was present in the gel (3.724% aq.), which contains the 2 amine fluorides olaflur (N’-octadecyl-trimethylenediamine-N,N,N’-tris-(2-ethanol)-dihydrofluoride) and dectaflur (9-octadecenylaminhydrofluoride).
The application of fluoride-containing toothpaste, gels, or drugs is commonly used to prevent caries. They contain several components with allergenic properties, such as abrasive and cleansing agents, colophony, flavourings, binding agents, preservatives, thickeners and colourings (1-3). There is no previous report of contact allergy to amine fluoride. Fluoride can also cause non-eczematous skin reactions: urticaria, perioral dermatitis, acne-like eruptions, or ulcerous stomatitis (4-7).
In addition, concentrations of fluoride above 0.5% may give non-specific pustular patch test reactions (1). However, we diluted the gel far below this value. Furthermore, 5 healthy control subjects did not show any reaction to amine fluoride at this dilution.