Antimicrobial photodynamic therapy (aPDT) is associated with photosensitizing agents which promote the generation of free radicals and singlet oxygen, which are cytotoxic to certain bacteria. Leukocyte and platelet-rich fibrin (L-PRF) has been used extensively in the treatment of intrabony defects and achieved excellent results. It acts as an immune regulation node with inflammation control abilities, including a slow continuous release of growth factors which stimulates periodontal regeneration. The aim of this study is to evaluate the adjunctive effects of aPDT with and without L-PRF in aggressive periodontitis patients.

Inclusion Criteria:

• systemically healthy
• non- smoker,
• not received any periodontal treatment within the last 6 months,
• no antibiotics, anti- inflammatory drugs or any other medication taken within the last 6 months

Exclusion Criteria:

• any systemic disease that might influence the prognosis of periodontal disease and outcome of the treatment,
• any medical condition that required antibiotic prophylaxis before the treatment,
• smoking,
• pregnancy and lactation,
• ingestion of antibiotics, anti-inflammatory drugs or any other medication during the study period,
• any physical limitations or restrictions that might preclude normal oral hygiene procedures.