T he rising cost of gold and precious metals has been instrumental in the development of nonprecious alloys in dentistry, including many nonprecious alloys that contain nickel. In recent years, nickel hypersensitivity in humans has been of growing concern among dentists. Contact with nickel by susceptible individuals may produce a spectrum of hypersensitive reactions. Dermatitis and urticaria, the primary manifestations of nickel hypersensitivity, may be found in the area of contact as well as distant from the nickel source.‘s2 Urticaria and dermatitis of the hands, neck, and eyelids are commonly reported hypersensitive reactions to nickel.’ Nickel is a known carcinogen and nickel ions are released from nickel-containing alloys in the oral environment.3a4 It is not known, however, whether the release of nickel ions from dental alloys is high enough to be clinically significant. If so, as a result of the potential alteration in endocrine functions, changes in vital functions such as blood pressure, pulse, and temperature might be expected. Nickel-containing alloys have been linked to a decrease in the number of T-lymphocytes in humans.4 Normal immune function depends on a balance of T4 helper lymphocytes that label foreign cells and microorganisms and T8 suppressor lymphocytes that prevent white blood cells from affecting normal cells.4B 5-8 Indeed, metal allergies from dental alloys have been implicated as a possible cause of the oral lesions of lichen planus.” Nickel contact dermatitis is commonly observed, with some references claiming as high as a 28% positivity in nickel sulfate patch tests among the general population.” The incidence of nickel allergy is higher in women (31.9%), presumably because of sensitization from nickel-containing jewelry. lo With increased use of nickel in nonprecious dental alloys, it would be logical to expect