Combined Periodontal-Endodontic Lesion In The Mandibular Molar

Endodontic-periodontal combined lesions of pulpal origin are typically initiated by pulp necrosis, which spreads microbial infection to periodontal tissues through apical foramina or lateral canals, resulting in deep periodontal pockets and rapid bone destruction. Early differentiation from primary periodontitis is critical to avoid unnecessary invasive interventions. A 28-year-old female reported pain and mobility in the right mandibular second molar. Clinical examination revealed a 10-mm distobuccal periodontal pocket with purulence and pulp necrosis confirmed by vitality tests. CBCT demonstrated localized periapical radiolucency and distal alveolar bone resorption without generalized periodontitis. Treatment involved microscopic root canal therapy under rubber dam isolation. Ultrasonic activation with 5% NaOCl disrupted lateral canal biofilms, followed by iRoot SP obturation using warm vertical compaction. No periodontal surgery was performed; oral hygiene instruction was provided. The resolution of deep periodontal pockets (from 10 mm to 3 mm) and radiographic bone regeneration at 6-month follow-up underscores the pivotal role of eliminating intraradicular infection. The case highlights that microbial dissemination via lateral canals—rather than primary periodontitis—can mimic severe periodontal destruction. Non-surgical root canal disinfection can effectively prevent the pathogen progression and promote the self-repair of periodontal tissue. This case proved that combined periodontal-endodontic lesion derived from dental pulp can achieve a good prognosis after perfect root canal infection control. Early diagnosis and differentiation from periodontitis is the key to prevent overtreatment.