الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Ridge preservation therapies have been proposed with the aim of maintaining the hard and soft tissue dimensions of the alveolar ridge that are partially lost after tooth extraction as part of the natural physiological healing process. There are many techniques in the literature used for socket preservation as bone grafts, barrier membranes, immediate implant and socket shield. Many other techniques also are used such as bone and tissue healing promoting molecules like recombinant human bone morphogenetic protein-2 (rhBMP-2). In the emerging area of growth factors, there is no high-quality evidence to either support or refuse their use.
Autologous blood preparations like platelet rich plasma (PRP), platelet-rich fibrin (PRF), and platelet rich in growth factors (PRGF) have been also introduced for socket preservation.
Plasma Rich in Growth Factors (PRGF) have given rise to an optimized and safer product rich in growth factors which might be essential to proper tissue repair and wound healing. PRGF acts on already differentiated cells, such as preosteoblasts and osteoblasts. However , they do not exert any effects on the stem cells present in bone tissue, whose differentiation is regulated by bone morphogenetic proteins (BMPs). Some pharmacologic compounds could offer a safe and cost effective alternative to this problem and can affect bone regeneration.
Statins are widely used group of cholesterol lowering drugs that act on the mevalonate pathway by being acompetitive inhibitors of the rate limiting enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase). Statins increase normal bone formation by promoting
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osteoblast proliferation and differentiation and protecting the osteoblasts from apoptosis. In addition, they reduce osteoclastogenesis by inhibiting osteoclastic differentiation. Statins increase BMP-2 gene expression and subsequently promote bone formation.
This study hypothesized that use of PRGF fibrin scaffold in socket preservation owing to its biocompatibility, ease of use, stimulation of production of growth factors and its effect on the already differentiated osteoblasts, when combined with statin with its effect on progenitor stem-cells could stimulate the differentiation of stem cells to osteoblasts, prevent bone resorption and stimulate bone formation at the extraction socket.
Thus this study was conducted to compare post-extraction augmented sockets using Atorvastatin loaded in Plasma rich in growth factors derived fibrin scaffold (PRGF/ATV) with the direct application of Atorvastatin (ATV) gel and spontaneously healed socket (Control) both clinically and by histomorphometric analysis of formed bone quality.
All groups showed significant loss of horizontal and vertical ridge dimensions after 2 months. Although there were no statistical significant differences between groups regarding mean percentage change in buccal and palatal ridge heights after 2 months, however group II (ATV gel) showed the lowest reduction in ridge height. Despite the significant reduction in ridge width reported in this study in all groups, the group I (PRGF/ATV) showed a dimensional loss of 20.4 (13.6) % which was higher and significantly different from that of group II (ATV gel) 9.6 (6.9) % and group III (Control) 5.2 (6.7) %.
The histomorphometric analysis revealed that the total collagen surface area was larger in stained sections from Atorvastatin gel group (group II)
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and was statistical significant different from that of the control group (group III) that showed the smallest total collagen surface area. While, the average trabecular size of mineralized tissue was the largest in stained sections from PRGF/ATV group (group I) followed by ATV gel (group II) and the smallest average trabecular size was in (group III) too.
The results of the present study showed that there was no significant difference between all groups regarding reduction in dimensions of residual ridge after extraction. However, significantly higher newly formed mineralized bone trabeculae and osteoid tissue in sites augmented with Atorvastatin loaded on PRGF fibrin scaffold and those augmented with Atorvastatin gel was detected after 8 weeks.
Further future invitro studies are recommended for investigating the optimum characteristics of this scaffold and statin release profile from it