A Randomized, controlled clinical trial and split-mouth design was performed to assess and compare the effect of platelet-rich fibrin (PRF) on soft tissue healing, periodontal pocket depth and alveolar bone height distal to second molar of the study and control groups after third molar surgical removal.

Sample include of participants who had indication of impacted lower third molars extraction on both sides with symmetrically orientation and same difficult index. All participants had same extraction protocol on both side at Department of Oral surgery, Faculty of Odonto-stomatology, University of Medicine and Pharmacy, Ho Chi Minh City.

Soft tissue healing, periodontal pocket depth and distal bone height were evaluation by an independent investigator.

Inclusion Criteria:

• Patient over 18 years old.
• Good general health.
• Bilateral lower third molars equivalent in inclination and Pell and Gregory's impaction classification (classification II, III and B, C). The assessment of equivalence between two mandibular third molars was determined on the panoramic radiograph.
• The difference of third molar inclination on both sides not greater than 15 degrees.
• The patient consented to participate in the study after hearing clearly the explanation of purposes and requirements of the study.

Exclusion Criteria:

• Patients with any systemic disease contraindicated for surgery.
• Presence of acute inflammation or infection at third molar areas.
• Patients refused to participate in the study, did not comply with treatment or did not come to the follow-up examination as required.
• The difference in surgical time between the two groups was more than 10 minutes.