[Biocompatibility of dental materials. Choice of testing methods: to do or not]

Three methods used to study the biocompatibility of dental materials are compared in this article. A glass-ionomer cement, Vitrabond, was studied, using gutta-percha as the control material. Specimens were standardized according to an original procedure. Unsterilized Vitrabond implants were used, because UV rays modify the material. Intraperitoneal Vitrabond implants increased the macrophage population in rats after 24 hrs. This was caused by the surgical trauma and indicates that this method is unreliable. The intramuscular placement of Vitrabond provoked well defined lesions after a week. The use of histochemical techniques on frozen muscle demonstrated that the concentration of succinic deshydrogenase and acid phosphatase enzymes were altered when compared to the control lesions. A comparison of enzymatic lesions and an evaluation of the areas of cellular growth inhibition during in vitro experiments using a computer image analyzer leads to quantitative conclusions that Vitrabond is a cytotoxic material. The simultaneous use of histochemical techniques on muscle tissue and cell culture in vitro enhances the validity of methods used to evaluate the biocompatibility of dental materials. These methods may be used to test the toxicity of various materials. Nevertheless, for a more complete evaluation of these materials, the allergenicity and carcinogenicity potential of these products should be evaluated, prior to the final verdict as to their biocompatibility.