The significance of sensitizing compounds in the denture base for the etiology of the burning mouth syndrome (BMS) has been studied in 53 denture-wearing persons, seven males and 46 females. Epicutaneous patch tests were performed with standard concentrations of benzoyl peroxide, dibutylphthalate, dimethyl-p-toluidine, formaldehyde, hydroquinone, methylmethacrylate, p-phenylendiamine and with cadmium sulfate, potassium dichromate, cobalt chloride and nickel sulfate. Furthermore, patch testing was performed with filings from the denture mixed with the patient's own saliva. In cases with an inflamed oral mucosa, the presence of hyphae of Candida albicans was assessed by a smear technique. Positive skin reactions were observed in 15 persons to dimethyl-p-toluidine, hydroquinone, formaldehyde, methylmethacrylate, p-phenylendiamine, potassium dichromate, cobalt chloride and nickel sulfate, including three cases with reactions to filings from their dentures, and one patient who after subsequent testing showed skin sensitivity to balsam of Peru. In 12 cases an etiological connection could be traced between the oral symptoms and the denture base, indicating that contact sensitivity to base materials or to allergens and microbial antigens on the denture plate plays a greater role in the pathogenesis of BMS in edentulous persons than previously suggested.

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Allergic contact dermatitis is mainly associated with xenobiotics and rarely with essential substances such as vitamins. Cronin (!) has surveyed previous case reports. Thiamine is vitamin Bl. Case ReportsCase no. 1. A 54-year-old nonatopic former grocer, employed in a pharmaceutical plant, filled and packed thiamine hydrochloride in a dusty process. After I month, he developed an itchy eczema on the forearms and dorsa of the hands, with some spread to the face.His condition did not improve with plastic gloves over most of the affected areas of the upper limbs, but disappeared on treatment with budesonide cream and 3 weeks off work. A severe flare-up followed immediately after resuming work, and he had to stop any work in contact with thiamine. He had had no recent oral intake of thiamine.Patch tests with thiamine 10%, 5% and I% aq. and thiothiamine 5% and I% aq. were applied with Finn Chambers® and read at 48 and 72 h, showing positive reactions to thiamine 10% and 5% aq.: thiamine I% aq. showed erythema only. Positive reactions were also recorded to thiothiamine 5% and 1% aq. A positive reaction was found to the inside of the used, but not the new, gloves. Testing with the European standard series was negative. Case no. 2A 32-year-old former baker had had to change his occupation due to rhinoconjunctivitis. Allergy was found to rye and a number of grass and tree pollens. 6 years earlier, he had for a short period been treated for atopic dermatitis. After 3 months of employment as a process worker in the same pharmaceutical plant as case no. I, he developed an itchy eczema on the hands and legs, which spread to the rest of the body. The eczema was exudative in places. On the dorsa of the hands and feet, it was severely infiltrated and more proximally, it had a reticular pattern.The patient was dismissed from work. The skin gradually cleared after treatment with betamethasone ointment. After discontinuation of topical treatment, however, an intermittent itchy dermatitis persisted on the dorsa of the feet, on the face, and occasionally at other sites. Further questioning revealed that daily he took oral vitamins containing thiamine.Patch testing (European standard series) showed positive reactions to formaldehyde and fragrance mix. He also reacted to thiamine hydrochloride 10% aq. The 2 former reactions were not considered relevant to the present dermatitis. Oral thiamine was discouraged.Patch testing of controls 10 other patients were tested with thiamine hydrochloride 5% and 10% pet. and aq. All patients had eczema but no known external contact with thiamine hydrochloride. They were all negative to all tests. DiscussionCases of allergic contact dermatitis due to thiamine have previously been reported among pharmaceutical workers. 2 patients filling ampoules developed allergic eczema of the hands and arms, and in I also of the eyelids (2). A girl filling vials developed ec-