Three-Session Non-Surgical Periodontal Therapy Improves Biochemical and Microbiological Profiles in Patients With Severe Grade C Periodontitis

This randomized, single-blinded, controlled clinical trial is conducted at the Department of Periodontology, School of Dentistry, Ege University, İzmir, Turkey. The purpose of the study is to evaluate whether a three-session non-surgical periodontal therapy protocol provides different clinical, biochemical, and microbiological responses compared to a single-session protocol in patients with Stage III/IV Grade C periodontitis. Participants with periodontitis are randomly assigned to one of two intervention groups: Single-Session Therapy Group (SSTG): full-mouth scaling and root planing (SRP) performed in one visit. Three-Session Therapy Group (TSTG): quadrant-wise SRP delivered over three sessions within the same week. All procedures are carried out by a single calibrated clinician. Clinical periodontal parameters-probing depth, clinical attachment level, plaque index, and bleeding on probing-are recorded at baseline and at predetermined follow-up visits at 1, 3, and 6 months. Gingival crevicular fluid samples are collected to quantify inflammatory biomarkers, including interleukin-1β (IL-1β), interleukin-6 (IL-6), clusterin, cystatin C, and osteocalcin, using multiplex immunoassays. Subgingival microbial profiles are evaluated using checkerboard DNA-DNA hybridization targeting a panel of selected bacterial species. The study protocol has received ethics approval from the Ege University School of Medicine Ethics Committee, and written informed consent is obtained from all participants. The research is supported by the Scientific Research Projects Coordination Unit of Ege University.