الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
 |  | from | 147 |  |  |
| | | from | 147 | | |
Abstract
The regeneration of bone has long been a critical issue in osseous defects. Many procedures have been developed for the purpose of promoting regeneration, especially when it comes to restoring critical sized defects. Such approaches include local application of growth factors, PRP, PRF, and stem cell therapy. Bone grafts are often necessary to provide a supporting scaffold; fill voids and enhance the biologic repair of bone due to their osteoconductive nature.
The aim of this study was to compare histologically and histomorophmetrically the effects of locally applied MTA alone or with Biphasic calcium phosphate on bone regeneration in standardized critical sized mandibular bony defects using rabbit models.
Thirty two healthy male New Zealand white rabbits weighing about 2.5-3 Kgs, aged 14-16 weeks were used in this study. Rabbits were randomly divided into 2 groups, 16 animals in each according to the observation period of 2 and 6 weeks after surgery. Osseous defects measuring 3 mm length ×3 mm width ×3mm depth were prepared in the edentulous left and right regions of the alveolar ridges of the mandible, using a sterile surgical bur. Right sided osseous defects were filled with Mineral Trioxide Aggregate (MTA), while left sided bone defects were filled with Biphasic calcium phosphate (BCP) and MTA.
After animal sacrifice the mandibles were dissected out, and sectioned into two halves. Each of the left and right halves were separately fixed immediately in 10% neutral buffered formalin and decalcified in 8% trichloroaceteic acid, washed, dehydrated in alcohol and embedded in parrafin wax.
Serial sagittal sections of 5μm thickness were cut and stained with Hematoxylin & Eosin.
Histomorphometric analysis was performed using the Image J software in order to obtain the percentage of area of the newly formed bone compared to the total surface area of the surgical defect.
I. Histological results
Results of the first observational period (two weeks postoperatively)
A-MTA group: Newly formed woven bone was seen growing from the lateral wall of the defect a short distance toward its center .The central part showed minute areas of early bone formation that appeared less mature compared with that formed close to the margins and was surrounded by connective tissue of variable denisty. This centrally formed bone was of the woven variety and enclosed a great number of osteocytes .
Also other regions of the defect contained dense aggregates of granulation tissue intermingled with specules and small trabeculae of newly formed woven bone towards the center of the defect.
The newly formed trabeculae were lined by discontinuous layer of voluminous osteoblasts and accommodated large number of osteocytes.
An evident line of fusion between the native bone and the newly formed bone could be traced.
B- MTA+BCP group: In this group, the bone defect contained aggregates of the grafting material surrounded by newly formed bone extending in different direction from the defect boundary.
The newly formed bone trabeculae contained a high density of osteocytes, lined by active osteoblasts and enclosed dense highly cellular connective tissue.
The defects in this group exhibited bone formation activity more than in MTA group and the formed trabeculae appeared thicker, contained larger osteocytes and exhibited outstanding figures of trabecular growth with occasional osteoclasts and remodeling lines.
The line of osteointegration between the native bone and the boundary of newly formed bone trabeculae at the periphery of the defect was more evident and included broader areas of contact with the two bone variants than in the previous group.
Results of the second observation period (six weeks post operatively)
A- MTA group: The margins of the defect were sealed by compact bone while the central part was filled with trabecular bone of varying thickness and density and were surrounded by fibrous connective tissue.
B- MTA+BCP group: The defects were almost filled compact bone which appeared to be of higher density than in the previous groups while there were small areas of trabecular bone mass near the central part of the defect. The compact bone consisted of numerous Haversian systems enclosing rich blood supply within their Haversian canals
II. Histomorphometric results
The mean values of the percentages of bone surface area formed during the healing of the bone defect in the MTA and MTA+BCP groups after 2 and 6 weeks were calculated and the results showed that the MTA+BCP groups exhibited statistically significantly greater percentage of newly formed bone compared with the MTA groups in both observation periods.