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|PRP Usage in Today's Implantology - Dr. Rudi Shapira - D.M.D.|
The need for an autologous hemostatic gel provoked the development of platelet-rich plasma gel(PRP gel). Autologous PRP was first introduced to dentistry by Marx et al. in order to improve bone healing. (see note 2) PRP is a product that contains elevated levels of autologous growth factors. These growth factors are maintained in the same ratios as in peripheral blood.
Platelet Rich Plasma (PRP) is composed of platelets, lymphocytes and plasma. Platelets are cells that are partially responsible for causing blood to clot. Platelets are a small disk or plate like structure. They are non-nucleated blood elements with very fragile membranes. Platelets adhere to uneven or damaged surfaces. The average human platelet count is 250,000/mm3. Platelets are formed in the red bone marrow by the fragmentation of megakaryocytes. Platelets contain large amount of natural growth factors. The platelet count in PRP can exceed 1 million platelets per micro liter.
Platelet degranulation is a physiologic process which proceeds upon contact with damaged vascular endothelium, collagen and other biochemical mediators. Physical damage to the platelet itself is to be avoided in order to preserve physiologic function, i.e., degranulation within the wound and not within the collection system. In theory, this would allow for the delivery of the greatest concentration of actual growth factors to the wound. PRP is more likely a concept of amplifying a biological event that is happening any how in an injured tissue.
Growth factors (more then 30 identified in platelets) shown to enhance the body's natural healing process include:
There are also others products available, such as recombinant synthetic growth factors: these products are usually synthetic derivatives of a single growth factor. Signals generated from PRP-derived growth factors reach local pluripotent, mesenchymal and epithelial cells and enhance their local migration, division and matrix synthesis. As a result, PRP has been suggested to increase the early rate of bone deposition and its quality during guided bone regeneration procedures. (see note 4)
2. The blood is placed in a special Harvest® centrifuge in order to separate the blood to its various cell populations divided in distinct layers.
3. The process is done a few minutes later when we obtain and recover the platelet-rich plasma (PRP) from among the specific layer.
4. The liquid PRP is then mixed with bone tissue, harvested from the donor site and mixed with particulated bone, with the aid of chemical additives, such as calcium thrombin, calcium chloride or procoagulum, it gels shortly later.
5. The resulting gel mass is then placed at the surgical site. The PRP should be activated and immediately placed at the surgical site; otherwise a significant portion of the growth factors will remain un transferred to the surgical site. Not activating the platelets correctly may cause premature rupture. Activated slowly or not in the surgical site, or transferring the clot to the site after waiting too long - means the coagulum is very condense (with or without bone added),contains some platelets and only a small quantity of growth factors.
As observed by some authors, PRP is meanful when acting on living cells- osteoblasts, osteoclasts, and fibroblasts. It has no meaning when used only with bovine bone, or banked bone alone.
1. Whitman DH, Berry DL, Green DM. Platelet gel: Autologous alternative to fibrin glue with applications in oral and maxillofacial surgery. J Oral Maxillofac Surg.1997; 55:530-531.
2. Marx R.E. et al./ Oral and maxillofacial surgery-1998;85:638-46.
3. Pierce GF, Mustoe TA, Atrock BW, Deuel TF, Tomason A. Role of platelet-derived growth factor in wound healing. J Cell Biochem 1991; 45:319-326.
4. The Influence of Platelet-rich Plasma (PRP) on Repair and Regeneration of the Bone Tissue in Surgical Maxillary Sinus Lift: a Study in vivo. 32nd Annual Meeting and Exhibition of the AADR (March 12-15, 2003)
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