الفهرس 
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Abstract
This study is carried out to assess the effect of application of collagen membrane on healing of alveolar bone and periodontal ligament fibers with ligature induced periodontitis in rats.
Forty-five adult male albino rats were used in this study divided into three groups fifteen in each. Rats were distributed into 3 groups: group A; (control group), group B; (ligature induced periodontitis) and group C: (ligature induced periodontitis with collagen membrane). Periodontitis was induced in group B and C by using ligature. Ligature was detached after 14 days. Collagen membrane was applied after ligature removal by surgical procedure. General behavior of rats of the different groups was measured at regular intervals throughout the time of the experiment.
Experimental rats were sacrificed from the ligature elimination at the end of week 12 form the beginning of the experimental study. Mandibles were dissected out from the animals and were prepared for histological examination and histomorphometrical analysis.
The difference in histological feature of the alveolar bone and periodontal ligaments healing at 12 weeks of the different groups in the molar area was examined by light microscope using heamatoxylin and eosin. Histomorphometric analysis was done to evaluate the percentage of the surface area of the formed bone .The value of the surface area of the formed bone in the different groups was assessed using the (Image J 1.46) software.
6.1.1 Histological results
Control group A
Microscopic examination of alveolar bone revealed normal structural design of alveolar bone. The bone surface opposite to the periodontal ligament disturbed by volkmann canal, healthy and intact PDL fibers inserted in the alveolar bone.
Ligature induced periodontitis group B
Microscopic examination of this group revealed alveolar bone destruction and more aggressive loss in bone height with detachment of PDL fibers, irregular resorbed alveolar bone surface and wide bone marrow spaces. Discontinuity of osteoblasts on bone surface was seen. Presence of empty lacunas of osteocytes was histologically detected. Many osteocytes with pyknotic nuclei were also observed. Large and multinucleated osteoclasts in Howship’s lacunae and resting lines were evident.
Ligature induced periodontitis with collagen membrane group C
The result was quite similar to study group A (control group). This group exhibited dense bone with relatively even and smooth boundary, normal size and scattering of osteocytes, well defined resting line were seen. It showed the normal orientation of PDL fibers.
6.1.2 Results of Histomorphometric analysis
The comparison between the three studied groups (Control group A, periodontitis group B and collagen membrane treated group C) regarding percentages of bone per field. The percentage of bone per field in periodontitis group B was still lower than the control group A and the collagen membrane treated group C.
However, the difference between the control group and group C treated by collagen membrane was not statistically significant Moreover, the difference between groups C treated by collagen membrane and group B was significant.