Can a Patient's own blood proteins help rebuild bone lost to gum disease?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults aged 18 to 65 years. * Diagnosis of Stage III periodontitis according to the 2017 classification of periodontal and peri-implant diseases and conditions. * Completion of nonsurgical periodontal therapy and oral hygiene instruction before surgical treatment. * Presence of at least one interproximal intrabony periodontal defect considered suitable for regenerative periodontal surgery. * Residual probing depth of at least 6 mm and clinical attachment loss of at least 6 mm at the selected site following nonsurgical periodontal therapy. * Radiographic evidence of an intrabony defect component of at least 3 mm at the selected site. * Adequate plaque control and compliance with oral hygiene instructions. * Ability to understand the study procedures, provide written informed consent, and attend all scheduled follow-up visits. Exclusion Criteria: * Current smoking or smoking cessation within the previous 6 months. * Uncontrolled diabetes mellitus, serious cardiovascular disease, autoimmune disease, liver or kidney failure, immunodeficiency, or another systemic condition that may adversely affect periodontal healing or surgical treatment. * Pregnancy or lactation. * Presence of a hematologic disorder, bleeding disorder, anticoagulant therapy, or another condition that may interfere with venous blood collection or periodontal surgery. * Use of antibiotics, systemic corticosteroids, immunosuppressive agents, bisphosphonates, antiresorptive agents, or other medications known to affect periodontal or bone healing within the previous 6 months. * Periodontal surgical treatment at the selected site within the previous 6 months. * Acute periodontal or endodontic infection at the selected site. * Untreated endodontic lesions, root fractures, extensive caries, or a hopeless prognosis involving the selected tooth. * Class II or III furcation involvement associated with the selected defect. * Known hypersensitivity to any material used in the study. * Inadequate oral hygiene or inability to meet the plaque-control requirements of the study protocol. * Current orthodontic treatment. * Inability or unwillingness to attend the scheduled follow-up visits.