Evaluation of Revitalization Success Using i-PRF in Non-Surgical Root Canal Retreatment

Apical periodontitis is a common consequence of failed root canal treatment and is primarily associated with persistent intraradicular infection. Although non-surgical root canal retreatment remains the standard treatment approach for failed primary endodontic therapy, reported failure rates range between 23% and 30%. Even after thorough chemomechanical preparation, complete elimination of microorganisms may not always be achieved. In addition, conventional treatment does not restore pulp vitality and may compromise the structural integrity of the remaining tooth tissue. Regenerative endodontic procedures have emerged as a biologically based alternative aimed at promoting tissue regeneration within the root canal system. By utilizing biological scaffolds and growth factor-rich preparations, regenerative therapy may enhance healing, support revascularization, and potentially restore natural defense mechanisms of the tooth. This study is designed as a randomized controlled clinical trial comparing conventional non-surgical root canal retreatment with regenerative endodontic treatment. The regenerative protocol incorporates injectable platelet-rich fibrin (i-PRF), an autologous blood-derived biomaterial obtained through low-speed centrifugation. i-PRF contains growth factors and bioactive components that may support angiogenesis, cell migration, and tissue repair. Following local anesthesia and rubber dam isolation, previously obturated root canal fillings will be removed. Standardized chemomechanical preparation and irrigation protocols will be performed according to the assigned treatment group. In the regenerative group, i-PRF will be applied as a biological scaffold prior to placement of a bioceramic material to achieve coronal sealing. In the conventional retreatment group, canals will be obturated using established root canal filling techniques. All procedures will be performed under standardized clinical conditions. Radiographic examinations will be obtained using positioning devices to ensure reproducibility and standardization of angulation. Patients will be monitored periodically over a two-year follow-up period to assess healing progression and treatment outcomes. This study seeks to provide evidence regarding the biological and clinical potential of regenerative endodontic therapy as an alternative to conventional retreatment in teeth with persistent apical periodontitis.