Using Platelet-rich Fibrin in Regenerative Endodontic Treatment in Mature Permanent Teeth

Inclusion Criteria: Participants had a single-rooted tooth with necrotic pulp (negative response to electric pulp testing), with or without periapical pathology (acute apical periodontitis of pulpal origin, chronic periapical periodontitis, periapical abscess with sinus, periapical abscess without sinus), and gave their consent to participate in the study. Exclusion Criteria: Study samples will be excluded if any of the following criteria are met: * The tooth has had previous endodontic treatment. * The root apex is not fully developed, or there is root resorption/cracking/fracture. * The tooth has severe tooth loss and is indicated for extraction, or is indicated for restoration with a post or cast core after endodontic treatment. * The root canal is calcified. * The root canal curvature is greater than 25º. * The tooth has a periapical cyst or is associated with a jawbone cyst. * The tooth has a periodontal pocket deeper than 4 mm. * The tooth has no occlusal contact. * The patient is pregnant. * The patient has diabetes or HIV or other immunocompromised conditions.