This study will evaluate the effect of PRF (platelet rich fibrin) on the healing of apicomarginal defects. Healing of the defects will be assessed 2 dimensionaly by periapical radiograph and 3 dimensionaly using CBCT.

Patients with apicomarginal defects as per the inclusion criteria will be randomly divided into two groups - (1) Test group - The denuded root surface will be covered by PRF (Choukron's method) and (2) Control group -No use of autologous platelet aggregate during periapical surgery. Radiographic and clinical healing will be assessed after 12 months, 2D healing will be assessed by Rud and Molven criteria and 3D healing will be assessed by Modified Penn 3D criteria.The clinical parameters recorded including periodontal pocket depth (PD), clinical attachment level (CAL) and gingival margin position (GMP) will be measured on buccal aspect of the interproximal space and mid buccal aspect of the involved teeth using Williams 'O' periodontal probe.Routine examination procedure will be used to evaluate any evidence of signs and/or symptoms.

Inclusion Criteria:

• A negative response to vitality tests with radiographic evidence of periapical radiolucency with no general medical contraindications for oral surgical procedures.
• Apicomarginal communication having probing depth > 6mm.
• Patients with no general medical contraindications for oral surgical procedures.
• Recurrent episodes of purulent discharge.
• Failed previous root canal treatment.
• Failed previous surgery with persistent bony lesion.
• Adequate final restoration with no clinical evidence of coronal leakage.

Exclusion Criteria:

• Clinical or radiographic evidence of root fracture.
• Resorptive processes involving more than apical third of the root.
• Any systemic disease contraindicating oral surgery including uncontrolled diabetes and pregnancy.
• Any condition effecting rate of healing like smoking.

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