الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
This study was conducted to evaluate histologically the osteogenic potential of corticocancellous block allograft versus Autogenous block graft in a surgically created bone defect in dogs.
The study was conducted on twelve healthy male adult mongrel dogs, about 18 – 24 months old, with an average weight of 9 – 13kgs,the dogs were all healthy as documented from veternians report, they were kept under the same nutritional and environmental conditions in the animal house at the physiology Department, faculty of Medicine, Alexandria University where operations and follow ups were performed, the dogs were kept for 1 week under constant observation before any surgical procedure to assess the health condition of the dogs.
Each animal received a dose of antibiotics in the form Ampicillin 25mg/kg body weight just before the operation.
All operating procedures were performed under general anaesthesia and sterile conditions in an animal theatre. Each animal was generally anaesthetized via intravenous injection of thiopenthone sodium the dose of which was calculated on a basis of 30mg/kg body weight.
Artificial bony defects were created in the mandible of the animals using trephine burs on each side of the mandible, one defect was prepared. In this way, a total of 24 experimental defects were made that were divided into two groups, group A where Puros corticocancellous block allograft was placed and in group B Autogenous block graft was placed.
All surgical sites were covered by the periosteum, muscles, fat tissues, and skin sutured with 2-0 Vicryl sutures.
Each animal received the same course of antibiotic Ampicillin 25 mg/kg body weight for five days after surgery every eight hours. Anti-inflammatories and analgesics were given in the form of ketolac IM (intra muscular) to the animals every eight hours for the first two days. The animals were observed daily for the first week to assess the presence of any signs of infection or any other complications.
Euthanasia to the dogs was done at (2,6 and 12 weeks) postoperatively by giving them an over dose of thiopentone sodium.
The jaws were dissected, and the specimens fixed in 10% neutral buffered formalin for 24 hours to be prepared for histological examination.
Demineralization was performed in 5% trichloro-acetic acid. The sections were processed and embedded in paraffin wax. Longitudinal serial sections were prepared to be stained with Hematoxylin and Eosin (H & E) and Trichrome stain for histological evaluation.
H&E stain was used to evaluate granulation tissue formation after 2 weeks, new bone (woven bone) formation after 6 weeks, and lamellar bone formation after 12 weeks, and also Trichrome stain was used for evaluation of collagen formation. The histological evaluation showed: Bone formation occurred in both groups A and B. After 2 weeks where a Puros corticocancellous block allograft was used there was proliferation of granulation tissue extravasated by blood corpusles in group A. Bone resorption at the periphery was well observed in addition to proliferation of inflammatory cells. After 6 weeks Numerous islands of woven bone were present. The formation of new trabeculae was less in amount compared with group B. After 12 weeks woven bone formation continued to occur and a larger number of inflammatory cells were evident In Group B (Autogenous block graft)
Histological analysis failed to demonstrate any pronounced infilteration of inflammatory cells in the tissue adjacent to the graft, immature bone formation was present. After 6 weeks. The examination revealed mild inflammatory cells and proliferation of granulation tissue. The site was invaded by bridges of lamellated bone. The bone- graft particles were still homogeneously stabilized in the defect area, new bone formation also followed the autograft scaffolds. After 12 weeks formation of lamellar bone in the form of bone trabeculae continued to take place.
These results showed that bone formation was more superior with the Autogenous block graft group compared with the corticocancellous allograft group.