This project is a randomized controlled clinical study investigating the effect of Mineral Trioxide Aggregate (MTA) used as an apical plug in root canal obturation on periodontal healing and inflammatory biomarkers in teeth with combined endodontic-periodontal (endo-perio) lesions. The study compares MTA with resin-based sealers and evaluates clinical, radiographic, and biochemical outcomes, including levels of IL-10, TNF-α, and MMP-8 in gingival crevicular fluid. The ultimate goal is to determine which treatment approach improves healing and increases tooth survival in such complex lesions.

This study includes 120 patients, divided into three groups: healthy controls, patients with combined endo-perio lesions, and patients with apical periodontitis only. Standardized root canal treatment will be performed under aseptic conditions. Teeth will be obturated using either MTA apical plug or resin-based sealer (AH Plus) following mechanical preparation and irrigation protocols.

Clinical and radiographic healing will be assessed using periapical index (PAI) scores, and gingival crevicular fluid (GCF) samples will be collected at baseline and during follow-up (up to 1 year) to analyze inflammatory biomarkers (IL-10, TNF-α, MMP-8). Periodontal treatment will be performed when required in combined lesion cases.

Inclusion criteria include patients aged 18-60 years, systemically healthy individuals, presence of radiographic periapical lesions, ability to provide informed consent, and willingness to attend follow-up visits.

Exclusion criteria include patients with severe systemic diseases (ASA III-VI) and teeth with advanced mobility (Miller Class ≥3).

Statistical analyses (t-test, Mann-Whitney U, Pearson and Spearman correlations) will be used to compare groups and evaluate relationships between healing outcomes and biomarker levels. The study aims to determine whether MTA provides superior biological and clinical outcomes compared to conventional sealers and to improve treatment strategies and prognosis assessment in endo-perio lesions.

Inclusion Criteria:

• Aged between 18 and 60 years Systemically healthy individuals Presence of radiographically confirmed periapical lesion Diagnosis of apical periodontitis and/or combined endodontic-periodontal lesion Ability to understand and sign informed consent Willingness to attend follow-up visits

Exclusion Criteria:

• Patients with severe systemic diseases (ASA III-VI) Teeth with advanced mobility (Miller Class III or higher) Patients unable to tolerate dental treatment procedures Patients unwilling to participate or attend follow-up visits

De-identified individual participant data underlying the published results will be made available upon reasonable request following publication of the primary study results.

Beginning after publication of the primary study results.

Access will be provided to qualified researchers upon reasonable request and approval by the study investigators.