Morphological Characteristics of Mandibular Molar Furcation Involvement and Efficacy of Regenerative Surgical Treatment

Inclusion Criteria: * Patients aged 18 years or older who signed the informed consent form. * Diagnosed with Stage III or Stage IV periodontitis according to the 2017 AAP/EFP classification. * Completed non-surgical periodontal therapy with full-mouth plaque score (FMPS) and bleeding on probing (FMBS) \<= 20%. * Presence of at least one mandibular molar with Hamp Class II furcation involvement (horizontal bone loss \> 3 mm without through-and-through communication). * Target tooth requirements: * Probing pocket depth (PPD) \>= 5 mm. * Clinical attachment loss (CAL) \>= 3 mm. * Tooth mobility \<= Grade I (Miller index). * Vital pulp or adequately filled root canal treatment without periapical radiolucency. * Gingival margin positioned coronal to the furcation entrance. * Intact tooth structure without root fractures or furcation caries. Exclusion Criteria: * Uncontrolled systemic diseases (e.g., uncontrolled diabetes, hypertension, cardiovascular disease, severe osteoporosis). * Pregnant or lactating women. * Current smokers or individuals who quit smoking less than 6 months prior to enrollment. * Use of antibiotics, anti-inflammatory agents, or medications affecting bone metabolism (e.g., bisphosphonates, high-dose corticosteroids, anti-resorptive drugs) within the past 3 months. * Previous periodontal surgery at the evaluation site within the past 6 months. * Target teeth presenting with: * Miller Grade II or Grade III tooth mobility. * Severe bone destruction extending to the root apex. * Metallic restorations (metal crowns, amalgam fillings, or large metallic posts) causing significant scatter/artifacts on CBCT scans. * Fused roots or abnormal root anatomy.