Leaching and cytotoxicity of formaldehyde and methyl methacrylate from acrylic resin denture base materials.

Acrylic resin dentures have the potential to elicit irritation, inflammation, and an allergic response of the oral mucosa. Studies of substances leachable from acrylic resins, their cytotoxicity to cultured cells, and means of reducing their leaching were systematically conducted. Under in vivo and in vitro conditions, formaldehyde and methyl methacrylate were significantly leached into human saliva and saliva-substitute buffer, especially from autopolymerized resins. Both leachable substances showed cytotoxic potentials in the range of their leaching concentrations. Formaldehyde was cytotoxic at lower concentrations than methyl methacrylate. Preleaching in water reduced subsequent leaching of both formaldehyde and methyl methacrylate, and the amount of reduction depended on an increase in the preleaching temperatures. Immersion of acrylic resin dentures in hot water (50 degrees C) before insertion is recommended, especially for autopolymerized resins used either for rebasing or as denture base materials, to minimize the risk of adverse reactions in patients who wear acrylic resin dentures.

[A case of nickel-induced stomatitis]. / Un caso di stomatite da nickel.

Some patients with prostheses or dental material containing nickel have been diagnosed as suffering from stomatitis. These lesions of the oral mucosa are sometimes difficult to interpret since allergies are not always taken into consideration. The paper reports a case of stomatitis due to nickel allergy and describes the diagnostic procedure [correction of iter] followed in order to diagnose the true nature of the pathology.

Contact allergy to denture materials in the burning mouth syndrome.

Several factors may be responsible for stomatitis in general and the burning mouth syndrome in particular. The results of patch testing are reported in 4 patients with burning mouth symptoms thought to be due to sensitization to denture material. 2 patients reacted to substances in Luxene dentures, but the allergens were not identified. In a 3rd patient, sensitization was found to monomeric methyl methacrylate. The other patient gave positive patch tests to epoxy resin (and bisphenol A), probably present in glue used for repair of dental plates. To obtain a complete diagnosis in cases of suspected contact stomatitis due to allergens in dentures, a reliable standard test series is required.

Allergic stomatitis from dental impression compounds.

Two women experienced a severe stomatitis following brief contact with Impregum, a dental impression material. In one patient it was shown that the sensitizer was the catalyst 2,5 dichlorobenzene sulfonate. This dental impression material is widely used in the United States, and has been reported as a sensitizer in Europe. The catalyst in Scutan, another dental impression compound sometimes used instead of the methacrylates, has also been reported in Europe as being a sensitizer.

Experimental Candida-induced denture stomatitis in the Wistar rat.

An experimental model of yeast-induced denture stomatitis has been set up in the rat by inoculating Candida albicans on the fitting side of a maxillary acrylic plate retained by an orthodontic band around the incisors. Thirty-eight Wistar rats were used in two series of experiments with an observation period of 2 weeks. In each of the series there were one control and three experimental groups. Control rats were left untreated, while rats of the experimental groups wore either uninoculated or inoculated plates, or had their palatal mucosa smeared with the yeast. For cytologic examination the palate was scraped in Series I and the fitting side of the plate in Series II. After 1 week a generalized simple inflammation had developed in the palate of most animals of the experimental groups. It was most severe and persistent in rats with inoculated plates. Histologic signs of inflammation and hyphal formation were also most pronounced in this group. Hyphae did not invade the epithelium. Except for an initial loss of body weight, which was restored by day 10 or 12, the rats tolerated their plates. The Wistar rat seems to be well suited for experimental studies on denture stomatitis.

Biological properties of denture base resins.

The biocompatibility and clinical efficacy of dental materials have been and continue to be a major concern of the dental profession. There are some cases of dental materials that have demonstrated problems with biocompatibility, for example, silicone soft liners. Although rare, allergic stomatitis caused by denture base resin is another example. High purity, very large polymer size, and nonoccurrence in nature significantly contribute to the acceptance of polymers used as biomaterials. New Federal Food and Drug Administration law and requirements of the specification and testing program of the American Dental Association will control the biocompatibility and clinical efficacy of dental biomaterials presently available to the dental profession.