This study investigates a biological approach that allows infected and necrotic teeth to heal themselves instead of being treated with traditional root canal therapy. Traditional root canal treatment involves cleaning the infected tissue inside the tooth and sealing it with a filling material, whereas regenerative endodontic treatment is a novel approach that enables the tooth to repair itself. This treatment method involves inducing bleeding in the root area or applying special blood derivatives (PRF types) to accumulate healing-supporting cells and growth factors. The aim of the study is to compare the effects of different biological treatment methods on the healing process, postoperative pain, and tooth discoloration. The results may help develop more effective and aesthetically successful treatment options in the future.

This study investigates the effectiveness of regenerative endodontic procedures in the treatment of necrotic and infected teeth. Traditional root canal treatment involves the complete removal of infected tissue from inside the tooth and sealing the root canal with a biocompatible filling material. However, this method does not restore the tooth's natural vitality or protective mechanisms. Additionally, it may increase tooth fragility and lead to discoloration over time.

Regenerative endodontic treatment is a biological approach that promotes the self-healing of the tooth. This method applies tissue engineering principles to stimulate the formation of new tissue within the root canal. During the treatment process, either bleeding is induced at the root tip or special platelet-rich fibrin (PRF) derivatives are applied to facilitate the accumulation of stem cells, growth factors, and immune-boosting components that support healing.

This study compares the effects of different regenerative treatment methods (bleeding induction, L-PRF, and I-PRF applications) on lesion healing, postoperative pain, and tooth discoloration. By determining the most effective method for teeth with completed root development and apical lesions, the study aims to establish an optimal treatment protocol for clinical practice. The findings will contribute to the development of treatment options that preserve the natural structure of the tooth, enhance aesthetics, and improve patient comfort and long-term treatment success.

Inclusion Criteria:

• Single-rooted teeth with mature teeth with necrotic pulp requiring endodontic treatment, and a periapical lesion (Periapical Index Score (PAI) ≥3).
• Individuals without systemic diseases, not using antibiotics, corticosteroids, antidiabetic, or antihypertensive medications, and not pregnant.
• Patients without acute pain.
• Patients without extraoral swelling, sinus tract, or acute apical abscess.
• Individuals willing to participate and able to attend follow-up sessions regularly.

Exclusion Criteria:

• Teeth with internal or external root resorption or vertical root fractures.
• Immature teeth.
• Individuals outside the age range of 14-65 years.
• Patients with complicated systemic diseases or those using antibiotics, corticosteroids, antidiabetic, or antihypertensive medications.
• Patients with acute pain, those who have taken analgesic medication in the last 24 hours, or those who have used antibiotics within two weeks before treatment.
• Patients who are unlikely to attend follow-up sessions.

The impact of gender differences on pain assessment in the study was also evaluated. Additionally, the effect of age on lesion healing was analyzed. Since the study examines the effects of demographic data on lesion healing and post-treatment pain, demographic data will be shared.