الفهرس 
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Abstract
The alveolar ridge is exposed to several environmental and physiological factors that affect its function and preserving its integrity. Before the era of implant dentistry there was no consideration to the problems that occurs in edentulous site after tooth extraction (Amler, 1969).
Many researches have been made to discuss the factors affecting the success of dental implants. It was found that successful osseointegration leads to successful dental implants. A literature review showed that primary stability of dental implants is one of the factors that can affect osseointegration (Javed et al., 2013).
Dental Implant placement in sites of severe bone resorption is a recognized challenge that could significantly influence the implant success. Actually, after tooth extraction, approximately 25% of bone volume has been reported to be lost after the first year. Over time, there is a great deterioration in bone loss (about 40-60%of bone volume) takes place during the first 3 years after tooth extraction. The vertical dimension of the alveolar process drops dramatically while the horizontal dimension reduced gradually (Carlsson et al., 1967).
For ridge augmentation to be successful, it should consider biologic and physical principles of bone in order to motivate the host response for regeneration. Bone grafting materials used to enhance healing in bone defects or to augment ridge defects has been evaluated in a number of experimental and clinical studies and has become a gold standard treatment in implant dentistry (Wang & Boyapti, 2006).
Graft incorporation seems to be enhanced when the bone marrow is exposed by perforating or decorticating the host bed. Perforations can provide access for blood vessels and progenitor cells from the endosteal compartment to the grafted area and can also strengthen the physical bond between grafted bone and recipient surface (Oh et al., 2011).
Due to several decortication drawbacks, nowadays multiple treatments were applied to the bone graft–bone bed Interface like interposition of platelet-rich plasma, bone morphogenetic proteins (BMPs), low-intensity laser and acid demineralization (cetric acid or EDTA) to produce stimuli to cellular activity resulting in greater bone deposition, bone volume maintenance, and reduced time for graft consolidation (Rezende et al., 2014).
Cetric acid has low pH which could have a cytotoxic effect on soft tissue and may hinder wound healing. EDTA has a 6.7 neutral pH so that EDTA is only a calcium chelator at this pH and does not have harmful or necrotizing effect on collagen or fibroblasts or osteoblasts. The demineralizing effect of EDTA promoted early cell and tissue colonization by providing a more biocompatible surface for cell and tissue attachment by removing the smear layer and the creation of surface roughness with collagen exposure (Lan et al., 1999).
In an in vitro study it was found that the neutral extracellular pH of osteoblast promote its metabolism. This give rise to the use of EDTA instead of citric acid to demineralize the bone surface and improve osteoblastic activity by surface modification and collagen exposure as well as the neutral pH which allow osteoblastic bone synthesis without affecting other cells or tissue (Blomlöf and Lindskog, 1995).
This study was conducted to compare the outcome of horizontal ridge augmentation after application of EDTA on the surface of cortical bone versus bone decortication, histologically and radiographically. Results showed that there is significant increase in bone width in group I, the bone graft to bone bed interface showed strong consolidation and the histomorhometric analysis showed significantly increased area percentage of new bone.
According to our results, EDTA bone surface etching can be considered as a more predictable and less morbid procedure to enhance bone formation and graft bed consolidation in different augmentation procedures.