This case report describes the diagnosis and multidisciplinary treatment of a clinically indiscoverable cementodentinal tear associated with a periodontal-endodontic combined lesion. The tear site was located at the palatal root surface of the maxillary left canine. Due to its position and concomitant periapical periodontitis, it was not noticed at the initial visit until a 3D CBCT examination was conducted. Through combined endodontic-periodontal therapy (which included root canal therapy, root debridement, and periodontal flap surgery), the tear fragment was removed, and the periapical lesion healed gradually. A histologic examination confirmed the definitive diagnosis of a cementodentinal tear. After 14 months, the periodontal and endodontic status of the maxillary left canine were stable. According to these results, CBCT examination and multidisciplinary cooperation seem to be effective and necessary for the diagnosis and treatment of such clinically indiscoverable cementodentinal/cemental tears.