Type 1 Allergy to Formaldehyde in a Root Canal Sealant Used for Dental Treatment

Abstract

　Immediate-type allergies caused by formaldehyde are rare but mostly severe, exhibiting general symptoms, while the time period between allergen exposure and onset is characteristically longer than normal immediate-type allergies. A 73-year-old woman, presented at her local dental clinic with a chief complaint of left maxillary tooth pain. The patient was diagnosed with acute suppurative pulpitis and underwent pulpectomy under local anesthesia. Five hours later, erythema and pruritus of the extremities appeared. After that, the patient repeatedly experienced mild fatigue during each session and visited our department 4.5 hours after the sixth session when erythema appeared in her abdominal region. Although 30 mg of prednisolone was administered, the erythema spread to her back and thighs, and blood pressure became unmeasurable. A prick test performed with formaldehyde, which was used at the initial consultation at the dental clinic and from the second treatment onwards, revealed a positive reaction. Formalin-specific IgE was class 4 (Index 36.90 UA/ml) , indicating a positive result. Thus, the patient was diagnosed with an immediate-type allergy caused by the formaldehyde contained in the root canal treatment. If anaphylactic symptoms appear after dental treatment, immediate-type allergies due to formaldehyde contained in root canal treatments should be considered.