The Present Study Was Performed to Evaluate the Efficacy of Lyophilized-PRF in Treatment of Periodontal Intra-bony Defects

Inclusion Criteria: * All periodontitis patients to be included in this study should be diagnosed as having stage III periodontitis with probing pocket depth (PPD) ≥ 6 mm, and clinical attachment loss (CAL) ≥ 5mm. * 2- or 3-wall intra-bony interproximal defect with depth ≥3 mm, a width of ≥3 mm at its most coronal part and 45-55-degree angulation will be selected in order to reduce defect variability. * All patients will be free from any systemic diseases according to the American Dental Academy general guidelines for referring dental patients to specialists and other care settings Exclusion Criteria: * Any patients with any systemic condition that contraindicate any surgical intervention. * Pregnant or lactating females, smokers, or alcoholic patients. * Patients with intra-bony defects received drugs that affect bone turnover such as (chemotherapy and radiotherapy). * History of periodontal therapy and antibiotic administration in the last 6 months. * Patients taking any medicine which may affect the function of platelet (i.e., aspirin) in the previous 3 months. * Miller grade II or greater mobility, furcation involvement as well as one-wall defects and interdental craters. * Patients with unacceptable oral hygiene after the re-evaluation of phase I therapy.