الفهرس 
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Abstract
T
ooth extraction is one of the most widely performed procedures in dentistry. It has been historically well documented that this may induce significant dimensional changes of the alveolar ridge (Horowitz et al., 2012).
A significant dimensional change occurs during the healing phase of extracted sockets. The walls of the socket shrink, and the changes are more apparent in buccal walls than in the lingual/palatal walls. Following tooth extraction, the ridge width decreases to about 50% in 12 months. Two-thirds of this change occurs in the first 3 months after tooth extraction. The final position of the socket walls is determined by the bone surface of adjacent teeth (Darby et al., 2009; Thoma et al., 2009; Farmer & Darby, 2014).
To reduce the loss of alveolar bone to an acceptable level, several alveolar ridge preservation (ARP) techniques’ procedures have been proposed. These have included the minimally traumatic extraction of a tooth, followed by immediate grafting of the extraction sockets using particulate bone grafts or substitutes, guided bone regeneration (GBR) with or without bone grafts or substitutes and a socket seal technique using different tissue graft materials (Mardas et al. 2010; Araujo et al. 2015).
The use of grafting materials as an adjunct to GBR or socket seal techniques is based on the assumption that this material may be useful not only in prohibiting membrane or soft tissue graft collapse into the socket area but also in enhancing new bone formation through osteoinduction and osteoconduction (Horvath et al., 2013).
Direct grafting and augmentation of the extraction socket has been proposed using autogenous bone, demineralized freeze-dried bone allograft, mineralized freeze-dried bone allograft, deproteinized bovine bone, alloplastic polymers, bioactive glasses and composite ceramic materials (Froum et al., 2002; Feuille et al., 2003; Mardas et al., 2010).
Many research studies to develop bone graft material to replace autogenous bone have been conducted. Kim et al. introduced a bone graft material using extracted auto tooth as new bone graft material to overcome the disadvantages of allograft, xenograft, and synthetic graft. Auto tooth bone graft material is an innovative bone graft material with all the advantages of autogenous bone owing to its very similar components to bone and is very useful in clinical situations (Kim et al., 2010 (a)).
The autogenous tooth graft material is a system that treats patients by manufacturing bone graft material from their own extracted teeth. Autogenous tooth graft material consists of 55% inorganic and 45% organic substances. Among the inorganic substances, hydroxyapatite (HA) has the characteristics of combining and dissociating calcium and phosphate as those of bone. Organic substances include the bone morphogenetic protein (BMP) and proteins with osteoinduction capacity as well as type I collagen, which is the same as alveolar bone itself. Therefore, they have the same bone remodeling capacity with autogenous bone (Kim et al., 2010 (a)).
The aim of the present study was to compare three months post-extraction augmented ridge with autogenous tooth graft covered by resorbable collagen membrane versus empty socket covered by collagen membrane only.
This comparison was done clinically, radiographically and histologically
Clinical parameters included; vertical bone height and bone width that were recorded at baseline and at three months after extraction. Radiographic parameters included superimposition of baseline CBCT and another one done three months after extraction with subsequent measurement of bone height, bone width and bone density. Moreover, histomorphometric parameters included; area fraction of osteoid and mature bone measured three months after extraction by histomorphometric analysis. Implant placement was also done three months after tooth extraction
In the present study we found that mean bone height and width decreased with a higher percent in collagen membrane group than autogenous tooth graft group without a significant difference between both groups.
Radiographically, CBCT superimposition revealed that a greater percent decrease in bone height and width had occurred in collagen membrane group than autogenous tooth graft group without a significant difference between both groups.
Accordingly, bone density increased in autogenous tooth graft group and decreased in collagen membrane group with a significant difference between both groups.
Finally, by histomorphometric analysis a higher mean surface area of osteoid bone was found in collagen membrane group than autogenous tooth graft group with a significant difference between both groups with a higher mean value of newly formed mature bone in autogenous tooth graft group without a significant difference between groups.