Immediate Reaction During Endodontic Treatment in a Patient with Formaldehyde Contact Sensitization: A Case Report of Generalized Urticaria with Angioedema

Formaldehyde is a well-known, ubiquitous chemical agent and a widely used skin sensitizer. There are reports of cases of systemic and localized allergic reactions attributed to formaldehyde (or formaldehyde-containing resins), which can occur during occupational exposure or daily life activities. It is included in many materials, such as cosmetic and household products, dental care products, topical medications, building materials, furniture and paints. In dentistry, patients may be exposed to formaldehyde and paraformaldehyde released from endodontic materials. Several side effects have been noted and published in the literature; however, up-to-date data are lacking. Our case report emphasizes the possibility that formaldehyde can cause an immediate hypersensitivity reaction and contact dermatitis. Therefore, the application should be reconsidered in dental treatment, especially if previously documented allergies are known.