The placement of dental amalgam restorations involves exposure to mercury, which can trigger severe allergic reactions in sensitized individuals. A history of mercury allergy is an absolute contraindication because even minimal exposure can cause systemic and localized hypersensitivity responses, potentially leading to significant morbidity. Alternatives such as composite or glass ionomer restorations should be used in these cases. Other listed conditions do not pose a systemic or immunologic risk that contraindicates amalgam placement. Therefore, patient safety mandates avoiding amalgam in those with mercury allergies.

Reference: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition.