الفهرس 
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Abstract
The purpose of this study was to evaluate the
effect of undifferentiated bone marrow stem cells,
biogen bone graft material and collagen scaffold on the
healing of periapical bone defects in dogs.
This study included 16 Canaan dogs of both sexes.
In all dogs both sides of the mandibles were used. One
defect was created on each side, with a total of 2 defects
bilaterally in each dog properly in the 4
th
premolar
region.
Lateral radiographic views were taken for each
dog preoperatively in order to exclude any dog with
apical radiolucency and to estimate the length of the
roots. Radiographs were performed under heavy
sedation.
The dogs were anaesthetized. Full thickness
mucoperiosteal flaps were performed. Proper reflection
and elevation of the flaps were done.
A total of 32 bone defects were created to expose
the periapical area of each root apex. Dimensions of the
defects were standardized (15 mm length x 10 mm
width x 10 mm depth). Root end performed on all roots included in the defects. A 3 mm
root end cavity was performed. All the retrograde
cavities were filled with white MTA.
The bony defects were divided into 4 groups (n=8)
according to the tested material. group I: Bone defects
were filled with the collagen scaffold; CollaCote. Group
II: bone marrow aspirates were obtained from the iliac
bone of four anesthetized dogs. Bone marrow aspirates
were diluted with phosphate-buffered saline and
mononuclear cells were isolated by density gradient
centrifugation. The bone marrow mononuclear cells
were washed, counted, loaded into the collagen scaffold
and then placed into the bony defect. group III: Bone
defects were filled with the Biogen bone graft material.
group IV: Bone defects were left to heal spontaneously
(negative control).
The flaps were repositioned in place after
placement of the materials and sutured. The dogs were
sacrified after 4 months.
After the animals were scarified, skin and
subcutaneous tissue were stripped off; the mandibles
were disarticulated, split and the mandibles were fixed
in a 10% formalin solution. resection was Evaluation of healing of the periapical bone
defects was done through:
Radiographic analysis:
All the split mandibles were submitted for CBCT
to measure the surface area and the volume of the
residual bone defects.
Histologic analysis:
For histological assessment of healing, the split
mandibles were cut in blocks and prepared for staining.
Sections were sliced through the center of each block,
and then the sections were stained with:
1- Hematoxylin and Eosin stain for assessment of
inflammatory cell count.
2- Goldner Tri-chrome stain for assessment of
percentage of bone formation and then observed under
light microscope.
Then, CBCT surface areas and volumes of the
residual bone defects, inflammatory cells and percentage
of bone formation were reported for data analysis.
The results of this study showed that for the
surface area of the residual bone defects, the bone
marrow mononuclear cells and biogen groups showed
statistically significantly lowest mean surface area values. There was no statistically significant difference
between them. Collagen scaffold group showed
statistically significantly higher mean surface area
values. The control group showed the statistically
significantly highest mean surface area.
For the volume of the residual bone defects, the
bone marrow mononuclear cells group showed the
statistically significantly lowest mean volume. There
was no statistically significant difference between
collagen scaffold and bone graft groups; both showed
statistically significantly higher mean values. The
control group showed the statistically significantly
highest mean volume.
For the inflammatory cell count, the bone marrow
mononuclear cells group induced the least inflammatory
response followed by biogen bone graft then collagen
scaffold and then the control group. There was a
statistically significant difference between the groups.
For the percentage of bone formation, the bone
marrow mononuclear cells group induced the highest
percentage of bone formation followed by biogen bone
graft then collagen scaffold and then the control group. There was a statistically significant difference between
the groups.