**7. Biological view of PRFs**

Understanding the biological properties of PRFs depends on having information about the content. Also, it is important to know the wound healing process to understand the effects of PRF. The healing of wounds is a process that starts with the hemostasis mechanism and continues with a series of events. The effect of PRFs depends on some key features. The first is the presence of the fibrin matrix. In this way, the fibrin matrix acts as a scaffolding where the cells providing the construction events migrate. The second is the fibrin matrix and the cells in it; secrete chemotactic proteins, cytokines and growth factors. The third is that the fibrin matrix and its factors induce vascular structure formation [4].

The effects of PRFs come from the elements in it. Its structure consists of fibrin matrix and cellular elements. The most important cell in its structure as a cellular element is of course platelets. In addition, its structure includes leukocytes, neutrophils, monocytes and mesenchymal stem cells. Growth factors, which are considered as the most important content of PRFs, are secreted by other cellular elements, especially platelets. The secretion of growth factors and their functions are very important for the functions of PRFs [4].

We know that PRFs provide secretion of many growth factors. These factors and effects are given below;

• TGF-β1: This molecule is an important inflammation regulator. It is also a very strong fibrosis agent. Its most important tasks are tissue repair, immune modulation and extracellular matrix synthesis. In addition, TGF-β1 plays an

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*Contemporary Overview of Blood Concentrates in Oral and Maxillacial Surgery*

a mitogen factor for osteoblast and fibroblast cells [4, 24–26].

It also provides chemotaxis in endothelial cells [4, 24–26].

cleavage and accumulation of osteoblasts [4, 24–26].

important role in collagen production. TGF-β1 also plays a role in restoring epithelialization and connective tissue healing. Transforming growth factor beta is also a critical mediator for bone formation. It stimulates the chemotaxis,

• PDGF: This growth factor known as platelet derived growth factor is important for the proliferation, migration and survival of mesenchymal cells. This growth factor also enables extracellular matrix production to occur during tissue healing. He is also involved in collagen production-demolition mechanisms. PDGF is also

• EGF: It stands for epidermal growth factor. The receptors of this factor are expressed in the majority of human cells, including cells that are important in wound healing stages. EGF stimulates the division of mesenchymal stem cells.

• VEGF: Vascular endothelial growth factor is most commonly secreted by

• IGF: Insulin-like growth factor is released when platelets are activated. It

platelets and macrophages. This growth factor is the most active growth factor for vascular regeneration. It provides angiogenesis and the formation of new blood vessels. In this way, blood flow and thus nutrition increase in injured

induces the differentiation and division of mesenchymal stem cells. IGF is also one of the mediators involved in the regulation of the programmed cell death process. Besides, IGF stimulates proliferation and differentiation in many cells of the body. IGF is also involved in bone matrix formation and replication of

The high healing potential and ingredients of the PRFs have brought to mind the ideas of both increasing the success and shortening the healing time by using them in sinus lifting procedures. Based on these ideas, PRFs were used in sinus lifting procedures, firstly mixed with grafts and then without using grafts. In studies conducted, it has been observed that even though there are no large differences in the amount of bone tissue obtained as a result of mixing graft materials and PRFs, it accelerates the maturation and the wound healing period. In addition, using PRFs mixed with graft materials makes the manipulation of the graft material quite easy. In addition, when PRF membranes are used in sinus lifting procedures instead of other membranes, PRF membranes have been found to be an inexpensive, easy-to-manipulate membrane, so they can be used to close lateral sinus Windows (**Figure 3**). When used for closing the lateral sinus window, it speeds up the healing process and provides good protection for the Schneiderian membrane (**Figure 4**). In cases where the Schneiderian membrane is perforated, PRF membranes are used to make a healing

Although PRFs have the expectation of controlling tissue inflammation with their special biological properties and providing good vascularization in bone tissue, the studies conducted have not yet shown a common understanding of their

*DOI: http://dx.doi.org/10.5772/intechopen.93865*

tissues [4, 24–26].

osteoblasts [4, 24–26].

barrier for the perforation zone [27–31].

effects in the literature [27–32].

**8.1 Sinus lifting**

**8. Clinical applications in maxillofacial surgery**

important role in collagen production. TGF-β1 also plays a role in restoring epithelialization and connective tissue healing. Transforming growth factor beta is also a critical mediator for bone formation. It stimulates the chemotaxis, cleavage and accumulation of osteoblasts [4, 24–26].

