Hypersensitivity to mercury, nickel and chromium in relation to dental materials.

Three metals which are used in dental materials are recognized as causing sensitization sufficiently frequently to consider whether problems might arise from their use in dentistry. These metals are, mercury, nickel and chromium. Nickel is by far the commonest sensitizer, 10 per cent of women are allergic to nickel; sensitization usually occurs through jewellery or fasteners on articles of clothing. Chromium (as chromate) is a much less common sensitizer for several reasons. Sensitization only occurs through hexavalent salts of chromate and the degree of exposure of humans to these salts is much less than to either nickel or mercury. The true incidence of mercury sensitization is difficult to ascertain because many of the materials which were used for patch testing previously and on which statistics were based, contained unnecessarily high concentrations of mercury, and the pattern of mercury allergy is changing because many substances which contain mercury and were used frequently are not now employed. Although metallic mercury can sensitize the evidence would suggest that if dental amalgams ever cause people to become allergic to mercury, it is an extremely rare occurrence. Problems with mercury-containing amalgams in those sensitized are also rare, only 28 cases have been recorded in the literature. Thus, it is likely that at the present time sensitization to mercury is uncommon and decreasing. There is even less evidence that nickel or chromate in dental materials actively sensitize and it is exceptionally rare to have problems with these metals in a prosthesis in someone who is already sensitized.(ABSTRACT TRUNCATED AT 250 WORDS)