Background: This series investigates the efficacy of regenerative endodontic therapy (RET) using various platelet-rich fibrin (PRF) formulations in treating apical periodontitis and necrotic pulp in immature permanent teeth. Aim: This study aims to evaluate the effectiveness of different PRF formulations in RET. Materials and Methods: Three cases involving patients aged 15–16 with immature teeth and necrotic pulp were treated with RET using PRF, injectable PRF, and advanced PRF. The procedure included inducing bleeding with a Hedstrom file, applying PRF variants, and sealing with mineral trioxide aggregate and composite resin. Patients were followed up at 1, 3, 6, 12 and 18 months. Results: Radiographic evidence showed apical closure, root maturation, and healing of periapical tissues in all cases. However, pulp sensibility tests were negative. Conclusion: RET using PRF variants promotes root development and apical healing in immature teeth. Further research with larger sample sizes is needed to understand these therapies’ potential and limitations.