Despite the widespread use of nickel-based alloys, claims for the safety of these alloys have not yet been accepted universally. The allergenic effects of nickel on dental patients and the potential toxic effects of nickel and beryllium on laboratory technicians continue to cause concern within the dental profession. The systemic response to metallic nickel and nickel compounds as a result of intraoral corrosion and dissolution of nickel-based restorations over extended periods have not been studied adequately. The dental profession may be overgeneralizing the relative safety of nickel alloys because of the lack of allergy-induced intraoral lesions observed in private practices. Additional animal studies are needed to characterize the acute and chronic toxicities of nickel compounds. The potential for dermatologic and systemic effects that may occur in patients and dental personnel because of exposure to cobalt alloys must not be overlooked. Although sensitivity reactions may be of some concern, the toxicity potential of cobalt-chromium alloys appears to be insignificant. Little research has been done to determine the carcinogenic potential of nickel in dental laboratory technicians. In addition, animal and human studies are needed to determine the effect of nickel and beryllium exposure on the reproductive system. In the interim, specific equipment and facilities that minimize dust and vapor exposure to dental technicians should be identified to reduce airborne concentrations of nickel and beryllium in commercial dental laboratories to levels well below those established by the Occupational Health and Safety Administration.(ABSTRACT TRUNCATED AT 250 WORDS)