This study evaluates the clinical effect of regenerative endodontic procedure using PRF in immature permanent teeth with apical periodontitis. Half of participants will receive the PRF instead of blood clots in the regenerative endodontic procedure, while the other half will receive a blood clots in the regenerative endodontic procedure.

The conventional method of regenerative endodontic procedure using a blood clot as scaffold materials has shown successful results. However, it is very difficult to induce bleeding and place mineral trioxide aggregate over a blood clot. Platelet-rich fibrin (PRF), a second-generation platelet concentrate. PRF is a matrix of autologous fibrin containing a large quantity of platelets, growth factors and leukocytes. PRF preparation technique is very simple, inexpensive and doesn't require any chemical agents. The purpose of this study is to test the hypothesis that the use of PRF in regenerative endodontic procedure of immature permanent teeth with apical periodontitis will accelerate periapical bone healing and stimulate the root maturation.

Inclusion Criteria:

• Between 6 and 18 years of age
• Provision of Informed Consent
• Cooperative in the dental chair
• Permanent immature teeth with apical periodontitis and incomplete root development

Exclusion Criteria:

• Have a medical history that may complicate treatment
• Unlikely to be able to comply with the study procedures