The goal of this clinical trial is to learn whether the size of apical preparation affects the success of regenerative endodontic treatment in mature permanent teeth with apical periodontitis. Regenerative endodontic treatment is a procedure that aims to eliminate infection and support healing of the tissues around the root of the tooth.

The main questions the study aims to answer are:

• Does a larger apical preparation improve healing around the root tip?
• Does apical preparation size affect pain after treatment or recovery of tooth vitality?

Researchers compared two treatment approaches that use different apical preparation sizes to see if one leads to better clinical and radiographic healing.

Participants:

• Received regenerative endodontic treatment with one of two apical preparation sizes
• Attended follow-up visits for clinical examination and radiographic evaluation
• Were monitored for pain and healing outcomes during the follow-up period

Inclusion Criteria:

• Single-rooted mature teeth with periapical lesions
• Teeth with a PAI score ≥ 3
• Patients aged 18-45 years
• Systemically healthy individuals
• Patients who provided written informed consent

Exclusion Criteria:

• Immature teeth
• Previously root canal treated teeth
• Teeth with a PAI score <3
• Developmental anomalies
• Advanced periodontal destruction
• Internal/external resorption
• History of trauma
• Patients with systemic diseases
• Pregnant or breastfeeding patients