Clinical Research Directory

Inclusion Criteria: * Age between 18 and 65 years. * Presence of a posterior tooth indicated for primary endodontic treatment (excluding retreatment cases). * Diagnosis of apical periodontitis, meeting the following criteria: * Necrotic pulp based on pulp vitality testing (negative cold test and/or electrical pulp test \[EPT\]). * Periapical Index (PAI) ≥3 on periapical radiography or presence of periapical radiolucency on cone-beam computed tomography (CBCT). * Asymptomatic or mildly symptomatic apical periodontitis (excluding cases of severe acute apical periodontitis). * Periodontal status meeting the following criteria: * Probing depth ≤3 mm. * Clinical attachment loss ≤2 mm. * No periodontal pockets with bleeding on probing. * The tooth to be treated must be suitable for isolation and sample collection. * Participants must be able to understand the study procedures and provide informed consent. Exclusion Criteria: * Use of antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), or -corticosteroids within the previous 3 months. * Presence of a systemic inflammatory or autoimmune disease. * Diabetes (glycated hemoglobin \[HbA1c\] ≥6.5%) or uncontrolled metabolic disease. * History of immunodeficiency or immunosuppressive therapy. * Pregnancy or breastfeeding. * Active smoking. * History of acute infection, febrile illness, or COVID-19 within the previous 3 -months. * Retreatment cases. * Presence of a fistula/sinus tract. * Periodontal probing depth \>3 mm. * Tooth mobility ≥ Grade II.