Platelet-rich plasma (PRP) is an autologous preparation of platelets in concentrated plasma. Although PRP has been used as a therapeutic tool to promote wound healing, the mechanisms underlying the wound healing effects of PRP remain unclear. The purpose of this study was to evaluate the effectiveness of applying PRP in the management of tooth extraction sockets.

Materials and methods: All three upper molars of 10-week-old male Fischer rats (200–220 g in weight) were extracted, and the bone between the molars was removed with round bur to create bone defects approximately 1 mm × 1 mm × 3 mm in size. Blood was drawn from the hearts of other rats, and PRP was prepared. The PRP was activated with calcium chloride and thrombin and applied to the bone defects of the experimental group. Meanwhile, 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 decalcified and studied histologically and immunohistochemically.

Results: 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, 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 and alveolar bone resorption were observed in limited areas of the bone defects in the control group, while thick granulation tissue and alveolar bone resorption were seen in wide areas of the bone defects in the experimental group.

Conclusions: The results demonstrated the presence of a rich fibrin network and early inflammatory reactions in the experimental group, which may lead to rise of thick, vessel-rich granulation tissue. Consequently, the application of PRP may stimulate wound healing in tooth extraction bone defects.