الفهرس 
Review of LiteratureOnly 14 pages are availabe for public view
 |  | from | 295 |  |  |
| | | from | 295 | | |
Abstract
Ovariectomy is the surgical removal of woman’s ovaries and it is established as the most prevalent and pertinent protocol to induce estrogen deficiency, bringing about hormonal deficiency similar to that of menopause. Post-menopause estrogen deficiency leads to increased and imbalanced bone turnover. The resultant altered bone turnover activity results in the net bone loss and reduction of bone quality (Osteoporosis) (Pacifici, 2006; Giro et al., 2011).
Osteoporosis is a progressive systemic disease that reduces, mineralized bone per unit volume, and degrades its microstructure. These factors increase significantly the bone fragility, leading to increased susceptibility to fractures. The disease is a public health problem because fractures lead to high costs for the healthcare service due to hospitalizations and associated drugs (Sandhu and Hampson 2011).
Several studies have reported a positive correlation between systemic osteoporosis and jaw conditions such as low mineral density in the mandible ,a large number of missing teeth, (Takaishi et al., 2005), changes in trabecular microarchitecture, and severity of residual ridge resorption (Yang et al., 2005; Liu et al., 2015).
There is debate as to the magnitude of osteoporosis effects on the bone quality of the jaws. Not all skeletal sites are equally susceptible to estrogen deficiency induced bone loss. For this purpose, the aim of the present study was to assess the effect of ovariectmy on cementum, periodontal ligament and alveolar bone of albino rats (histologically, immunohistochemically and scanning electron microscopic study).
MATERIALS AND METHODS:
Thirty adult female albino rats (12-week old) were used in this study weighing between 200-250 grams. The rats were equally divided into the two groups (control and experimental) and study period was (4 months):
group I (control group): It consisted of 15 rats that was subjected to sham operation.
group II (experimental group): It consisted of 15 rats that was subjected to ovariectomy operation.
By the end of the experiment period (4 months), blood samples were collected from both groups and the levels of estrogen in the sera was measured using the Enzyme Linked Immunosorbent Assay (ELISA).
And also, the rats of all groups were killed separately by cervical dislocation and their heads were immediately dissected to obtain the mandibles from both groups, the molar areas of the mandibles were dissected. Thus, 2 samples (right and left molar areas) from each rat were obtained.
One side of the molar area of each rat was identified and prepared for light microscopic examination by routine histologic examination (hematoxyline and eosin stain) as well as the immunohistochemical assay using antiosteonectin antibody to assess the histology of cementum, PDL and alveolar bone. The other side was prepared for scanning electron microscopic examination (15 samples from each group).
Results:
Light microscopic results:
(I) Hematoxylin and Eosin stain:
1-Control group: Cementum examination revealed that both types of cementum appeared with normal histological structure of cells and matrix. PDL examination revealed that the principle fibers were arranged in regular manner and the fibers are attached to cementum and alveolar bone by Sharpy’s fibers. And also, alveolar process examination revealed that the alveolar process appeared with normal architecture and thickness with entrapped osteocytes.
2- Experimental group Cementum examination of this group revealed that acellular cementum appeared in irregular manner due to resorption and remarkable variations of cementocytes within their lacunae. And, PDL examination revealed that disarrangement of the fibers orientation in all the fiber groups and some fiber bundles were detached from cementum and alveolar bone surfaces, in addition complete loss of fibers was detected in some regions. Alveolar bone examination revealed that remarkable thinning of bone trabeculae and widening of bone marrow spaces. Multiple resorption bays giving the border of the alveolar process irregular. Moreover, some osteocytes were completely degenerated leaving empty lacunae, while others showed signs of degenerations.
II- Immunohistochemical results: 1-Control group: Examination of sections stained with anti-osteonectin antibody showed weak immunoreactivity in cementoblast and moderate to weak reactivity in cellular cementum, cementocytes and extracellular matrix (ECM).And also, PDL showed positive immunoreactivity in fibroblast cells of collagen fibers and ECM.Alveolar bone examination showed that the ECM of bone and osteocytes are positively stained. The endosteum was intensely stained.
2- Experimental group: Examination of sections stained with anti-osteonectin antibody showed negative immunoreactivity for osteonectin in cementoblasts and very mild to negative reactivity for in cementocytes and ECM. PDL sections showed a decrease in the staining intensity for osteonectin compared with the control group.Moreover, alveolar process sections showed ECM and osteocytes are very weak immunoreactivity for osteonectin.
III-SEM results: 1-Control group: Cemrntum examination demonstrated the root surface that showed regular cracks with no signs of resorption and showed external cuts from Sharpey’s fibers inserted into the cementum. PDL and alveolar bone examination confirmed results of histological study.
2-experimental group: Cementum examination revealed that cracks on the surface of the cementum relatively wider than those on the control group and irregularities and multiple resorptive areas infiltrating the cementum surfaces.PDL and alveolar bone examination showed the same results obtained by the histological study.