2-Hydroxyethyl methacrylate (HEMA): A clinical review of contact allergy and allergic contact dermatitis. Part 2. Cross- and co-sensitization, other skin reactions to HEMA, position of HEMA among (meth)acrylates, sensitivity as screening agent, presence of HEMA in commercial products and practical information on patch test procedures

This is the second part of a literature review of the clinical aspects of contact allergy to and allergic contact dermatitis from 2-hydroxyethyl methacrylate (HEMA). Topics include cross- and co-sensitization, atypical manifestations of contact allergy, frequency of positive patch tests to HEMA compared with other (meth)acrylates, sensitivity of HEMA as a screening agent, the presence of HEMA in commercial products, and practical information on patch testing procedures. Primary sensitization to methacrylates including HEMA may result in methacrylate and acrylate cross-sensitization. There is a strong cross-allergy between HEMA, ethylene glycol dimethacrylate (EGDMA), and hydroxypropyl methacrylate; many reactions to EGDMA are cross-reactions to primary HEMA sensitization. Rare atypical manifestations of HEMA-allergy include lichen planus, lymphomatoid papulosis, systemic contact dermatitis, leukoderma after positive patch tests, and systemic side effects such as nausea, diarrhoea, malaise, and palpitations. The occurrence of respiratory disease caused by methacrylates such as asthma is not infrequent. HEMA is the most frequently patch test-positive methacrylate. It is a good screening agent for allergy to other (meth)acrylates. Patch test sensitization to HEMA 2% pet. is extremely rare. There are (some) indications that HEMA is frequently used in dental products and nail cosmetics.

The safety and biocompatibility of direct aesthetic restorative materials

Restorative dental materials are among the most important medical devices in terms of the numbers of patients who benefit and the technical sophistication of the products. Many though contain toxic or noxious substances, including potentially sensitising resin monomers, photoinitiators, acidic polymers and glass or ceramic filler particles. Despite this, dental materials are among the safest medical devices in use today, with very few reports of adverse reactions or injuries among both patients or the dental team. This paper considers the potential for adverse reactions to dental materials, current evidence for harm and finally examines the reasons why in real-world clinical use the likelihood of an adverse event is extremely low. Medical devices regulations, responsible manufacture and clinical vigilance all appear to play important roles in ensuring that dental materials do not cause or present a risk to patients. While this excellent in-practice safety record is welcome, there is now increasing interest in the 'macro' scale biocompatibility of dental materials and their packaging in the environment, subjects that have been relatively neglected until recently. It was concluded that this should be a priority for future research and development and support is needed from governments alongside the manufacturing industry and the profession.

Methacrylate perspective in current dental practice

OBJECTIVE

To provide a current perspective concerning dental personnel sensitivity to methacrylate materials.

OVERVIEW

Methacrylate related sensitivity and allergies are currently beyond traditional thoughts concerning denture base resins and methyl methacrylate provisional materials. Methacrylates are now ubiquitous in current dental practice and dental personnel should be aware that dental adhesives contain potent sensitizers that may also cross-sensitize individuals to other methacrylates not experienced. The growing sensitivity to 2-hydroxyethyl methacrylate (HEMA) has been described to be epidemic in nature due to the artificial nail industry with dental patients and dental personnel may be more susceptible to dental methacrylate sensitization. While contact dermatitis remains the most prevalent methacrylate-related clinical presentation, respiratory complications and asthma are increasing associated with methacrylate exposure. While additional personal protective equipment (PPE) is thought to be first protective choice, the National Institute for Occupational Safety and Health (NIOSH) considers PPE overall largely ineffective and should be considered only as a last resort.

CONCLUSION

Dental personnel need to be more aware of methacrylate sources and use workplace control measures to limit methacrylate exposures to both dental personnel and patients.

CLINICAL SIGNIFICANCE

Sensitivity to methacrylate materials is a growing dental workplace major concern and dental personnel should be aware of both the methacrylate content of current materials and the products that contain ingredients with the most sensitization potential.