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.