###### Abstract  
The aim of this study was to compare the effect of using L-PRF in patients undergoing impacted lower third molar surgery with either primary or secondary closure techniques. Methods: This prospective, randomized, double-blind, split-mouth clinical trial was conducted on patients with bilateral impacted lower third molars of a similar position. Primary closure was performed in group 1 and secondary closure in group 2. The group 1 closure technique was applied to one side of the patients, and the group 2 closure technique was applied to the other side at different times. Of the 45 patients evaluated, 9 patients were excluded from the study because of alveolitis and failure to attend regular control visits out. Results: Of the 36 patients included in the study, 23 were female and 13 were male, with a mean age of 22.42 \(\pm\) 3.36 years. The secondary closure group had lower VAS scores at hour 6 (\(p\) < 0.05). Pain decreased more in the primary closure group when comparing changes between the VAS scores at 6 hours and 7 days (\(p\) < 0.05). Conclusions: The results of this study, showing that both secondary and primary closure are effective, with similar outcomes in terms of pain, swelling, and trismus, should be supported by future clinical trials. leukocyte and platelet-rich fibrin; closure techniques; wound healing; regenerative medicine; primary closure; secondary closure; impacted third molar  
Appl. Sci.202414228. [[https://doi.org/10.3390/app1410228](https://doi.org/10.3390/app1410228)]([https://doi.org/10.3390/app1410228](https://doi.org/10.3390/app1410228))  
Academicother hand, secondary closure involves allowing the wound to heal via granulation and re-epithelialization [4; 5; 6]. It appears that primary closure has advantages over secondary closure in terms of postoperative infection, facial swelling, and trismus after lower impacted third molar surgery. This may be due to open flap debridement. However, some studies suggest that primary and secondary closure result in similar postoperative complications. For example, a systematic review by [PERSON] et al. showed a higher incidence of infection with primary wound closure compared with secondary intention to allow the wound to heal. However, the confidence intervals were wide and favored both methods of healing. It is not clear why this should be, but it is the case that pain and trismus have been shown to be reduced with primary closure compared with secondary intention healing. On the other hand, [PERSON] et al. concluded that there was insufficient evidence to recommend either primary or secondary closure techniques. This is because the nature and quality of the data have been unjustified and imprecise over the years. This makes it difficult to determine the best techniques to use, especially as surgical training becomes more competency-based [4; 5; 7; 8]. Leukocyte and platelet-rich fibrin (L-PRF) therapy is currently an area of significant interest in the field of regenerative medicine. This special type of platelet concentrate is now being used to accelerate the healing process in oral and maxillofacial surgical procedures involving both soft and hard tissues [9]. L-PRF is a simple and completely natural treatment option that does not require anticoagulants, bovine thrombin, or other additives. The procedure involves taking blood before surgery and centrifuging it for 12 min. This creates a pliable membrane and a collection of platelets- and growth-factor-rich clots held together by fibrin. The top layer, known as the red layer, has a high concentration of platelets that release growth factors as the fibrin matrix is formed. Of paramount importance is the layer known as the buffy coat, which consists of white cells, platelets, and significant amounts of fibrin. Fibrin plays a crucial role in the body's healing process and in the formation of connective tissue after trauma. The white cells in L-PRF are trapped and stimulated as part of the natural healing mechanism.