Dental materials: Where and why nickel is used
Concerns are sometimes expressed about materials, including nickel, that are used in dentistry. Indeed, under the general heading of "dental", a very wide range of materials is used for restorative work (fillings, crowns, bridges, partial dentures) and orthodontic appliances (wires, bands, brackets, etc.). Organic chemicals are also used, as examples, to disinfect, seal surfaces or act as adhesives.
Nickel has been used since the 1920s in different forms and for different applications. It has a number of desirable properties. Nickel will make a soft material (gold) harder. When combined with titanium, it becomes a shape-memory alloy of particular interest in orthodontics. Also, if the performance of a nickel-containing material is similar to, for instance, palladium, platinum or gold, nickel may be chosen because it is relatively inexpensive.
The amount of nickel in any alloy used in dentistry can vary from a few percent to over 50%. Note that the amount of nickel in an alloy is not indicative of the amount of nickel that might be released when in the mouth and in contact with surfaces or with saliva: different alloys will have different levels of corrosion resistance and hence different levels of nickel release.
The use of nickel-containing materials in dentistry has sometimes been reported as a source of adverse reactions. Evidence of significant problems is lacking, however. The range of materials used in dentistry, including many chemicals, is large and includes a number of known allergenic substances of which nickel is only one. Moreover, at least some adverse reactions might be explained by the trauma of the original work, poorly fitting appliances, or infection underneath a restoration.
If you are at all concerned about a possible adverse reaction as the result of the use of a nickel-containing material in restoration, surgical or orthodontic work, you should discuss this with your dental and medical specialists.
If you want to learn more about where nickel is used in dentistry, a good general reference is the "Dental Materials Fact
Sheet" of the Dental Board of California, the authority that licenses dentists in that State. A more
technical review of dental materials and health effects (with in-depth coverage of nickel-containing
materials) has been produced by the Nickel Producers Environmental Research Association (NiPERA): "The Safety of Nickel in Dental Alloys"
For more information on nickel allergy, go to "Nickel Allergic Contact
Dermatitis"
