Latex

Latex allergy occurs in approximately 1-5% of the population, but may be as high as 17% in healthcare workers (HCWs). In dentistry, latex allergy increased significantly in the mid-1980s, following the need for glove protection against, among other things, HIV and other blood-borne pathogens. Due to this widespread use, HCWs and dental patients are placed at increased risk of exposure and allergy development. Latex-free options are available for use as a result.

Metals

Allergies to metals in dentistry are also frequently reported. In particular, allergy to nickel in females is reported to vary from 9-20% and is ranked within the top three causes of allergic dermatitis (symptoms can include dryness, redness, itching, flaking, scaling, cracking or blistering). However, it is ranked first in most industrialised countries. In orthodontic patients with pierced ears, 30% are allergic to nickel, copper and chromium. However, only 1-3% of patients without piercings demonstrate similar allergic hypersensitivity. The recent popularity of oral piercings has put susceptible patients at a greater risk of developing metal allergies. The low incidence of nickel allergy in males (1-2%) will most likely increase and possibly also in females, if the oral piercing fashion continues or increases. Although rare, allergy to other metal alloys such as mercury, gold, platinum, palladium, silver and cobalt are also possible.

Resins

Di- and mono-methacrylate resins occur in many dental materials, from restorative composites to fissure sealants, bonding agents and orthodontic and crown and bridge resins. Although the occurrence of allergies to dental resins is low, most methacrylates can nevertheless induce a Type IV (delayed) allergic hypersensitivity reaction. In addition, eugenol-containing products and polyether impression materials also pose an allergenic risk to dental patients.

Type IV reactions can occur after one or two days following exposure to the allergen, whereas Immediate (Type I) reactions can occur almost immediately following exposure with, among other things, itching of the skin or mucosa, a burning sensation, erythema (reddening), oedema (swelling through accumulation of fluid) of the skin or mucous membranes, rhinitis or lightheadedness.

What action should be taken?

Suspected allergies in dentistry should be confirmed by an allergy test conducted by a dermatologist or allergist, due to the potential for a life threatening allergic reaction or the development of a long-term occupational disability. When an allergy test to a certain dental material is found to be positive, the dental team should take appropriate precautions to eliminate the use of the offending allergen by using alternative materials, for example, latex-free gloves or nickel-free alloys.

Research demonstrates that there are numerous potential allergens in everyday dental practice. However, currently there is not enough evidence to indicate that use of popular dental materials should be discontinued. Nevertheless, the dental team should remain vigilant and acutely aware of the potential of the many available dental materials and products to cause allergic hypersensitivity within the mild to severe range, both intra-orally and at unrelated parts of the body. Materials that warrant particular awareness include latex, nickel, methacrylate, eugenol and polyether impression materials.

References available from the author on wiltshir@cc.umanitoba.ca.