A study of nickel allergy.

N ickel is a potentially allergenic material. It is one of the most common causes of allergic contact dermatitis, particularly in women. l-5 Nickel can also be considered an occupational allergen. Nickel contact dermatitis is common among industrial workers, especially in those industries that use nickel as a raw material. It has been demonstrated that U.S. S-cent coins contain approximately 25% nickel and that they can induce eczematous contact dermatitisbm8 A great number of daily use objects that contain nickel and can therefore cause contact dermatitis have been rep0rted.j. 6. “, !” It has been demonstrated also that nickel-containing metallic orthopedic implants are linked to the produc?ion of sensitization dermatitis.‘i-1’ The “nickel itch” dermatitis caused by jewelry worn on the body or by occupation in nickel industries such as electroplating represents about 5% of all eczema in humans.14 .4s these alloys become more popular in dentistry, the frequency of allergic reactions should become more significant in the susceptible population and may result in inconvenience and expense for the patient who wears a prosthesis that contains the allergenic substances. The ability of a metal to induce dermatitis appears to he related to its pattern and mode of corrosion. All base metals corrode. In vitro investigations have shown that most nickel-based alloys have relatively high rates of corrosion compared with dental gold alloys. Products that result from this corrosion could produce a soft rissue inflammation reaction and thereby initiate a sensitization dermatitis. Implants that contain nickel and chromium, with the exception of those fabricated from stainless steel, corrode in tissue fluids and facilitate migration of nickel and chromium to the surrounding tissue.“-” Many studies concerning nickel hypersensitivity have been reported.‘4-‘7 Numerous authors agree that there is a great variety of factors that can influence the development of hypersensitivity to nickel. The most important are mechanical irritation, skin maceration, individual susceptibility, temperature, climate, and intensity and duration of exposure.‘, 3, 4, 9. I8 Mechanical irritation and skin maceration promote sensitivity. An increase in temperature causes increased sweating and the chloride ion present in perspiration ionizes the nickel present in the alloys. In this way nickel salts are formed that induce skin hypersensitivity reactions.’