An Experimental Study on the Effects of Platelet Rich Plasma on the Wound Healing Of Tooth Extraction-Related Bone Defects.
After being anesthetized using sevoflurane inhalation and the intraperitoneal administration of chloral hydrate, all three upper molars of 10-week-old male Fischer rats were extracted, and the bone between the molars was removed with a round burr to create bone defects approximately 1×1×3 mm in size. Blood was drawn from the hearts of other rats, and PRP was prepared. The PRP preparation was obtained from age-matched Fisher rats. Heart puncture with an 18-G needle and exsanguination were performed, and blood was collected into tubes. The tubes were centrifuged at 450x G for 10 minutes. After the first spin, the serum, buffy coat and red cells located 2 mm under the buffy coat were aspirated, collected into another tube and centrifuged at 850x G for 15 minutes. The PRP was collected at the bottom of the second tube and activated with bovine thrombin and calcium chloride. The PRP was applied to the bone defects of the experimental group while nothing was applied to the bone defects of the control group. The rats were sacrificed on days 1, 3, 5 and 7. The specimens were fixed with 20% buffered formalin and decalcified with EDTA. Serial sections measuring 7 µm in diameter were obtained and stained with hematoxylin and eosin. The sections were studied immunohistochemically for type IV collagen in order to visualize the basement membrane, and specific staining was also performed to visualize collagen fibers.
The results showed that inflammatory cells and a fibrin network were observed under the PRP layer in the bone defects in the experimental group, whereas inflammatory cells and a fibrin network were rarely seen in the control group on day 1. On day 3, only inflammatory cells and a fibrin network were observed in the bone defects of the control group, while conglomerates of inflammatory cells, a fibrin network and granulation tissue, which is abundant in blood capillaries, were seen under the PRP layer in the experimental group. On day 5, a thin layer of granulation tissue was observed in limited areas of the bone defects in the control group, while thick granulation tissue was seen in wide areas of the bone defects in the experimental group. On day 7, granulation tissues were seen in bone defect of both control group and experimental group, but concavity was seen in the control group and a thicker granulation layer was observed in the experimental group. At the point of epithelialization, earlier epithelialization was seen on thicker granulation tissues on days 5 and 7 in the experimental group compared to the control group.
In conclusion, in this study, PRP treatment induced a rich fibrin network and early inflammatory reactions in the experimental group, which may have led to the development of thick, vessel-rich granulation tissue with early epithelialization. The growth factors secreted from the granulation tissue may therefore have led to the observed early wound healing in the experimental group. Consequently, the application of PRP may stimulate wound healing in tooth extraction-related bone defects.
References;
1. Efficacy of Platelet-Rich Plasma on Wound Healing in Rabbits. H W. Lee et al.; J Periodontol 2008; 79: 691-696.
2. Platelet-rich plasma (PRP) in dental and oral surgery: from the wound healing to bone regeneration. Albanese et al; Immunity & Ageing 2013 10: 23.