الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 107 |  |  |
| | | from | 107 | | |
Abstract
Alveolar bone loss following tooth extraction is problematic for dentists, because they can compromise both the functional and aesthetic outcomes of subsequent dental treatment. Socket grafting has been advocated to preserve alveolar bone and to improve bone healing.
The aim of the study was to evaluate two different methods used for promotion of extraction socket healing (clinically and histologically) .
The present study was conducted on twenty seven mature male Mongrel dogs free of any disease. The animals were equally divided into three groups. group I; were left without treatment as untreated control, group II; the extraction sockets were filled with autologous PRF alone and group III; the extraction sockets were filled with a combination of β-TCP alloplastic bone graft mixed with autologous PRF.
All animals in this study were subjected to the same surgical procedures under general anesthesia to extract the second mandibular premolar but in groups II and III prior to beginning the extraction procedures; platelet – rich fibrin was prepared by collecting 10 ml of the animal blood in a collection / separation tube without anticoagulant, then centrifuged at 3,000 rpm for 12 minutes .
The surgical wound was primarily closed with interrupted sutures and the residual ridge dimensions were measured by divider and ruler.
The healing of the extraction sockets was evaluated and compared clinically, histologically and histo-morphometric analysis at 3, 6, 12 weeks after surgery .
Post-operative assessment of the current study revealed no obvious complications; neither post-operative infection nor wound dehiscence or an inflammatory response was detected in any case. The clinical data showed that the synthetic β-TCP was bio-compatible and non- allergic.
All groups showed no dimensional changes 3 weeks after surgery, but 6 and 12 weeks post-operatively, the ridge dimensions of the extraction sockets changed. group I (control group) showed pronounced extraction socket resorption, group II (PRF group) showed enhanced alveolar socket preservation, while group III (PRF- mixed β-TCP group) showed extraction socket enlargement, demonstrating significant difference statistically.
On histologic evaluation; group II showed more early bone formation, remodeling and calcification because no fibrous connective tissue was found at 3, 6 and 12 weeks post-operatively as compared to group I and group III .
In a histo-morphometric analysis; there was significant difference statistically between the groups in the new bone formation ratio. Although group II showed the most rapid bone healing histologically, but group III showed the largest bone formation area at 3, 6 and 12 weeks post-operatively. The control group showed lower bone formation area than either of the experimental groups throughout the intervals.
Finally, it was found that the experimental groups had more bone formation properties than control group. This finding is probably attributed to the osteogenic effect of the growth factors released from PRF at the initial bone formation stage. Also, β-TCP probably acted as a scaffold for PRF. Thus, the use of PRF- mixed β-TCP for extraction socket healing is thought to have a synergestic effect on bone healing as in group III leading to more bone formation area than group II .
from the present study, it could be concluded that :
• The use of PRF is a successful procedure for extraction socket healing and alveolar ridge preservation. The use of PRF is a simple method that requires minimal cost and reduces the need for specialized grafting material.
• However, PRF- mixed β-TCP graft material showed synergestic effect on bone healing, demonstrating that a mixture of autologous PRF and the synthetic β-TCP bone graft can be used for reconstruction of large bone defect and extraction socket with destructed walls.
• PRF and PRF-mixed β-TCP represent a promising advance in the clinical application of maxillofacial surgery.