Clinical Research Directory

Inclusion Criteria: General (for all participants): * Age between 18 and 65 years * Individuals capable of providing written informed consent * Systemically healthy * Individuals able to adhere to the instructions for the study day (pre-sampling protocol) * No heavy exercise on the day of sampling Group-specific criteria: Periodontal Health Group: * BOP \<10% * PD ≤3 mm * No interdental CAL * No clinical or radiographic signs of periodontitis Gingivitis Group: * BOP ≥10% * PD ≤3 mm * No interdental CAL * Not meeting criteria for periodontitis Periodontitis Group: Systemically healthy individuals diagnosed with periodontitis (Stage III-IV) according to the 2017 World Workshop classification criteria, confirmed by clinical and radiographic examination. Stage III periodontitis is diagnosed with interdental CAL is ≥ 5 mm, radiographic bone loss (BL) extends to mid-third of the root and beyond, tooth loss may become evident ≤4 teeth. Either PD ≥ 6 mm or vertical BL ≥ 3 mm, or Class II/III furcation involvement, or moderate ridge defect. Stage IV periodontitis is diagnosed with interdental CAL is ≥ 5 mm at the site of greatest loss, radiographic BL extending to mid-third of the root and beyond. ≥5 tooth loss due to periodontitis is evident. In addition to Stage III, either masticatory dysfunctio two separate GCF samples will be collected from each participant in the periodontitis group: one from the deepest periodontal pocket in the mouth and one from a clinically healthy site in the same individual. Exclusion Criteria: Systemic conditions: * Diabetes mellitus (diagnosed or HbA1c elevation or under treatment) * Autoimmune or systemic inflammatory diseases * Chronic renal or hepatic failure * Malignancy * Uncontrolled endocrine disorders (thyroid disease, Cushing syndrome, etc.) * Pregnancy or breastfeeding Tobacco and nicotine use: \- Active use of cigarettes, hookah, electronic cigarettes, or any nicotine product Medications and treatment history: * Antibiotic use within the past 3 months * Regular systemic NSAID or corticosteroid use within the past 1 month * Immunosuppressive therapy * Medications affecting bone metabolism (bisphosphonates, denosumab, etc.) * Periodontal treatment (scaling and root planing or surgery) within the past 6 months * Professional dental prophylaxis within the past 3 months * Body mass index (BMI) ≥30 (obesity) or BMI \<18.5 (underweight)