This study aims to compare the ability of different regenerative protocols in the treatment of mature necrotic

American Dental Association adopted the tissue engineering concept and pulp regeneration in 2009. Regeneration was focused on the treatment of immature necrotic teeth so as to allow root completion, improving both the functionality and durability of the affected tooth. Utilizing a blood clot in the affected tooth with immature roots was very beneficial, as it acts as a scaffold for the migration of stem cells and morphogens to allow regeneration .

Based on the success of pulp regeneration in treating immature teeth, ambitious dentists started to look forward on regenerating the pulp of mature teeth as a substitution to the conventional root canal treatment. On the other hand, lots of clinicians were very doubtful about treating mature teeth with the same protocol, as the small apical foramen might not provide a good portal for the entry of stem cells and growth factors, which in turn is very important for the success of pulp regeneration.Doubts in treating mature apex encouraged researchers to look for an alternative to the stem cells other than the apical papilla, from this concept the idea for using an alternative source of stem cells and growth factors as platelet rich plasma (PRP) emerged. The use of platelet rich plasma (PRP) as a potentially ideal scaffold for regenerative endodontic therapy has been reported in the treatment of immature teeth. However, the use of bovine thrombin for the activation of PRP has been an issue of controversy, as it requires non autologous anticoagulant known to hinder the process of pulp regeneration.

This led to the development of the second generation, platelet concentrate known as Choukroun's platelet rich fibrin (PRF) which is totally autologous in nature. Platelet rich fibrin (PRF) was very promising, but it is debatable whether to use PRP or PRF.The objective of this study is to evaluate novel regenerative techniques, utilizing platelet rich plasma and platelet rich fibrin in treatment of second premolar teeth with necrotic pulp, mature apex, and periapical lesion. This is a trial to prolong the survival of the affected tooth, and to aid in complete healing of periapical lesion, and to regain pulp vitality and sensitivity.

Inclusion Criteria:

• Patients who are free from any physical or mental handicapping condition with no underlying systemic diseases.

Non-pregnant females Single canalled second premolar

• Patients having non-vital, mature, second premolar teeth, radiographic evidence of periapical lesion.
• Positive patient/Guardian compliance for participation in the study.

Exclusion Criteria:

• Any known sensitivity or adverse reactions to medicaments or pharmaceuticals necessary to complete the trial.

Non-restorable coronal portion of teeth involved in the trial. Vital teeth Immature teeth Traumatized teeth Radiographic evidence of external or internal root resorption. Any criterion, not mentioned in the inclusion criteria