A cemental tear involves complete or incomplete separation of the cementum on the root surface along the cementodentinal junction. Because a cemental tear can lead to periodontal breakdown and mimic endodontic and periodontal lesions, diagnosing clinical cases can be difficult and requires special examinations. A 72-year-old woman presented with a localized periodontal defect on the labial and interproximal surfaces of the mandibular right central incisor. Performing CBCT scans and a biopsy during periodontal surgery allowed definitive diagnosis of a cemental tear and perforation of the site. First, the perforation was repaired with endodontic therapy. Periodontal regenerative therapy using recombinant human fibroblast growth factor-2 (rhFGF-2) was then performed after removing granulomatous tissue and cementum fragments. Examination of the biopsy specimen showed bacterial colonies. This case showed successful clinical and radiographic outcomes at the 18-month follow-up.