A tooth is endodontically treated through an access opening cut in an existing full crown. One week later the crown fractures. The most likely reason is:

Cutting an endodontic access through a crown removes tooth and restorative material, and an endodontically treated tooth is already weakened and dehydrated. Without adequate remaining structure, ferrule, and cuspal protection, the crown and tooth fracture under function.Other options: Antifungals are irrelevant; gutta-percha allergy is extraordinarily rare and would not fracture a crown; pulp does not regenerate after obturation.Key exam takeaway: Endo-treated teeth are weaker and access through a crown removes structure; restore with cuspal coverage and adequate ferrule to prevent fracture.