Combined endodontic-periodontal lesions involving the pulp and periodontal tissues are difficult to treat and have a poor prognosis.This article reports a case of combined endodontic-periodontal lesions with severe alveo-lar bone loss in maxillary first molar.The patient was treated with a combination of root canal therapy,initial perio-dontal therapy,guided tissue regeneration,and simultaneous apical surgery to ach...