CD03 Heavy is the crown: hidden allergy in dental restorations

Abstract A 50-year-old woman was referred to the cutaneous allergy clinic for investigation of chronic aphthous ulceration that had developed after being fitted with metal dental braces at age 13 years. Over the years, documentation and photographs confirmed numerous aphthous ulcers affecting all oral mucosal surfaces. At around 20 years old, she had a dental filling placed in the right upper third molar; the material used (amalgam or resin composite) is unknown. She later sustained trauma to her right central incisor, resulting in devitalization of the tooth, which was covered with a crown restoration of unknown composition. At age 25 years, she underwent patch testing to the European standard, preservative, fragrances, steroids, local anaesthetic, metals and dental series, plus her own products. She had positive reactions to balsam of Peru, nickel sulfate, palladium and mercury. She was advised on allergen avoidance; however, she did not seek further evaluation regarding her dental restorations. Management included betamethasone soluble tablets as a mouthwash, fluticasone propionate spray, plus benzydamine mouthwash and/or Anbesol® gel as needed. Colchicine was trialled but subsequently discontinued due to intolerable side-effects. She was re-referred to the cutaneous allergy clinic due to the severity and chronicity of her symptoms. Interestingly, at the time of attendance in 2025, vitamin B12 replacement injections the preceding year had significantly improved her symptoms. She underwent repeat patch testing to the British Society for Cutaneous Allergy standard series, as well as the cosmetic, fragrances, glucosides, bakery, acrylates, metal and dental series, and her own products. Positive reactions were identified at 96 h to mercury, phenyl mercuric acid, mercury amidochloride, nickel sulfate, palladium chloride, sodium tetrachloropalladate and vanadium chloride, in addition to benzydamine mouthwash and Corsodyl toothpaste. Short-contact (20-min) patch testing to the fragrance and bakery series revealed positive reactions to cinnamyl alcohol, cinnamal, sorbic acid, benzoic acid and propionic acid. She reattended after suspected delayed reactions, later confirmed as strongly positive responses to beryllium sulfate tetrahydrate and bornanedione (formerly camphorquinone), occurring at 10 and 17 days, respectively. Bornanedione is a rare contact allergen found in dental adhesives and resin composites. Alongside other positive allergens in the dental series, it may be relevant to the clinical problem given her previous dental restorations. Among 651 patients patch tested to the dental series (2002–2025), only three have tested positive for bornanedione, all presenting with intraoral reactions linked to previous dental procedures. This case raises awareness of bornanedione and highlights a delayed reaction to this rare contact allergen. This is an important consideration for all doctors and dentists particularly in the context of a nationwide rise in cosmetic dentistry.