Impacted mandibular third molars can cause various complications to the adjacent second molars, such as dental caries, periodontitis, or root resorption. These complications often progress silently and asymptomatically. A typical scenario involves a mesioangularly impacted third molar exerting pressure on the distal alveolar bone of the second molar, resulting in persistent food impaction that is difficult for patients to clean. Furthermore, the surgical removal of deeply impacted or severely angulated mandibular third molars often requires bone removal in the area adjacent to the second molar. These factors may exacerbate distal periodontal defects of the second molar, especially in individuals over the age of 25. This research focuses on evaluating the effectiveness of a new-generation collagen membrane in promoting healing after the extraction of impacted mandibular third molars in patients at risk of distal periodontal tissue damage to the second molars

Inclusion Criteria:

• Patients aged 25 years or older.
• Patients with mesioangular or horizontally impacted mandibular third molars. The highest point of mandibular third molars are lower than the occlusal surface of adjacent second molars (classified B, C according to Pell - Gregory's category).
• Patients with symmetrical lower third molars on both sides with same classification according to Pell - Gregory's category. The difference of third molars inclination on both side is not more than 15°.
• Patients with lower second molars on both sides have no cavities or fillings that affect the determination of the cemento-enamel junction.
• Patients are explained, counseled clearly and sign their consent to participate in the study.

Exclusion Criteria:

• Patients with coagulation or immune disorders.
• Patients allergic to local anesthetics (Lidocaine 2% with Adrenaline 1:100,000) or any drugs used in the study.
• Patients allergic to products or food derived from pigs.
• Pregnant or breastfeeding patients.
• Patients who smoke.
• Patients with systemic conditions that contraindicate surgical procedures.
• Patients with clinical or radiographic signs suggestive of tumors (benign or malignant) associated with or in proximity to the mandibular third molar.
• Patients with missing mandibular second molars.