To evaluate the security and efficacy in the administration of encapsulated acellular system derived from Mesenchymal Stem Cells as a novel regenerative endodontic procedure which to promote the pulpar regenration.

Inclusion Criteria:

• Systemically healthy patients (ASA I).
• Patient presenting with a maxillary or mandibular incisor/canine and mandibular premolar with mature apex, pulpal necrosis, and apical radiographic evidence of apical periodontitis (PAI ≥2 and CBCTPAI ≥1).
• Patient presents with a tooth that does not respond to electrical and thermal pulp testing.
• Patients with restorable teeth (considering the definition of class A or B, according to Samet and Jotkowitz classification) without the need for a single fine prosthesis (crown) or major restoration.

Exclusion Criteria:

• Patients not available for the follow-up period (27 weeks).
• Patients who will undergo orthodontic treatment in the next six months.
• Patients with reports of allergies to any material or medication used in the study.
• Pregnant patients.
• Heavy smokers (more than 10 cigarettes per day).
• Patients with a history of systemic diseases that impair immune function, such as diabetes mellitus, immunodeficiency, leukemia, Addison's and Cushing's disease.
• Patients who have used immunosuppressive drugs or chemotherapy, 3 months before the study. Or that they will be irradiated or undergo chemotherapy.
• Patients who have endodontically treated teeth.
• Patients who have teeth with signs of severe root resorption.
• Patients who have teeth with mobility class III or Dens invaginatus.
• Patients who have teeth with a history of avulsion-type dentoalveolar trauma.
• Patients who have teeth with clinical and/or radiographic evidence of root fracture.
• Patients who have teeth that cannot be completely isolated with rubber dam.
• Patients who have teeth with more than one root or root canal.