This randomized controlled clinical study evaluated whether concentrated platelet-rich fibrin (C-PRF) provides additional clinical and radiographic benefits when used together with minimally invasive non-surgical periodontal treatment (MINST) in patients with advanced periodontitis and intrabony periodontal defects.

Thirty systemically healthy patients with stage III-IV periodontitis were included. Each participant had at least one intrabony defect with a probing pocket depth of 6 mm or greater and a radiographic intrabony component of 3 mm or greater. Participants were randomly assigned to receive either MINST alone or MINST combined with C-PRF application.

Clinical periodontal measurements, including probing pocket depth, clinical attachment level, plaque score, bleeding on probing, and gingival recession, were recorded at baseline and at the 6-month follow-up. Standardized periapical radiographs were used to evaluate radiographic outcomes, including total defect depth, intrabony defect depth, defect angle, and linear bone fill.

Periodontitis is a chronic multifactorial inflammatory disease associated with dysbiotic dental biofilm and progressive destruction of the tooth-supporting tissues. In advanced periodontitis, vertical alveolar bone loss may result in periodontal intrabony defects. These defects are clinically important because they are commonly associated with deep periodontal pockets, clinical attachment loss, bleeding on probing, and increased risk of further periodontal breakdown if not adequately treated.

The management of periodontal intrabony defects traditionally includes non-surgical periodontal therapy as the initial treatment approach. However, in advanced cases, residual deep pockets and persistent inflammation may remain after conventional non-surgical therapy. Minimally invasive non-surgical treatment (MINST) has been proposed as a tissue-preserving approach for the management of intrabony periodontal defects. MINST aims to remove subgingival biofilm and calculus through careful instrumentation while minimizing trauma to the periodontal tissues. The technique emphasizes the preservation of the interdental papilla and marginal gingiva, limited tissue manipulation, avoidance of aggressive root planing and gingival curettage, and support of stable blood clot formation within the defect.

In this study, MINST is performed using fine periodontal instruments and thin ultrasonic tips without flap elevation. The objective of this approach is to achieve effective subgingival debridement while preserving soft tissue architecture and supporting periodontal wound healing. The minimally invasive nature of the procedure may be particularly relevant for patients with advanced periodontitis, where maintaining gingival tissue stability and reducing postoperative morbidity are important clinical goals.

Platelet-rich fibrin (PRF) is an autologous platelet concentrate obtained from the patient's own blood. PRF contains platelets, leukocytes, fibrin, and growth factors that may contribute to wound healing, angiogenesis, tissue repair, and periodontal regeneration. Concentrated platelet-rich fibrin (C-PRF) is a liquid PRF formulation prepared by collecting the cell-rich fraction from the buffy coat layer after centrifugation. Compared with liquid PRF protocols, C-PRF is designed to provide a higher concentration of platelets and leukocytes in a small volume, potentially increasing its biological activity at the application site.

Although several studies have evaluated different adjunctive biomaterials with minimally invasive periodontal therapy, evidence regarding the use of C-PRF together with MINST in advanced periodontitis remains limited. Therefore, this study is designed to evaluate whether the adjunctive application of C-PRF may provide additional clinical and radiographic benefits when combined with MINST in patients with stage III-IV periodontitis and periodontal intrabony defects.

This is a single-center, prospective, randomized controlled clinical study conducted as part of a doctoral thesis in the Department of Periodontology at Altinbas University. A total of 30 systemically healthy participants diagnosed with stage III-IV periodontitis are included. Each participant has at least one periodontal intrabony defect with a probing pocket depth of 6 mm or greater and a radiographic intrabony component of 3 mm or greater.

Participants are randomly allocated into two treatment groups. The control group receives MINST alone. The test group receives MINST followed by adjunctive C-PRF application into the periodontal pocket associated with the selected intrabony defect. For C-PRF preparation, venous blood is collected from the patient and processed according to the C-PRF protocol. The concentrated liquid fraction is then applied locally into the periodontal pocket after completion of the MINST procedure.

Clinical periodontal measurements are recorded at baseline and at the 6-month follow-up. The evaluated clinical parameters include probing pocket depth, clinical attachment level, plaque score, bleeding on probing, and gingival recession. Measurements are performed using standardized clinical methods, and site-specific values are recorded for the selected intrabony defect sites.

Radiographic assessment is performed using standardized periapical radiographs. Customized radiographic stents are used to improve reproducibility of radiographic image acquisition between baseline and follow-up. Radiographic measurements include total defect depth, intrabony defect depth, defect angle, linear bone fill, and defect fill percentage. These measurements are used to evaluate changes in the morphology and depth of the intrabony defects over the 6-month follow-up period.

Patient-reported outcome measures are also evaluated using visual analogue scale scores. These assessments are included to evaluate patient-centered outcomes such as pain, satisfaction, and aesthetic perception following treatment.

Inclusion Criteria:

• Individuals aged 18 to 70 years.
• Systemically healthy individuals.
• Individuals diagnosed with Stage III or Stage IV periodontitis.
• Presence of at least one periodontal intrabony defect with a radiographic intrabony defect depth of ≥3 mm.
• Presence of probing pocket depth of ≥6 mm at the selected defect site.
• No periapical pathology associated with the selected tooth.

Exclusion Criteria:

• Pregnancy or lactation.
• Presence of systemic diseases or use of medications that may affect periodontal healing.
• Periodontal treatment within the recent period before enrollment.
• Smoking ≥10 cigarettes per day.
• Presence of periapical pathology associated with the selected tooth.

Individual participant data will not be shared because the data contain confidential clinical information and were collected under ethical approval and informed consent for the purposes of this study only.

The outcomes assessor who performed clinical and radiographic measurements was masked to group allocation.