الفهرس 
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Abstract
The parotid salivary glands of rats are capable of endocrinal secretion, dispensing their secretions directly into the blood stream so the present study investigated the regulatory function of the parotid salivary glands on serum amylase enzyme and serum calcium, also whether the parotid gland endocrine secretions have an impact on bone healing or not.
Forty two adult male albino rats (weighing about 200 to 250 gm each) were used in this study. The animals were equally divided into two main groups:
• group I (Control): Animals of this group were subjected to unilateral surgical mandibular defects on the right side using a trephine drill of 3mm diameter.
• group II (Experimental): Twenty one rats were subjected to unilateral mandibular defect as in group I in addition to bilateral surgical removal of the parotid glands.
Each of the control and experimental groups was further subdivided into 3 subgroups. A, B and C according to the time of termination correspond to 4, 8 and 12 weeks respectively.
Before each scarifying time of both groups, blood samples were obtained in order to determine Calcium and Amylase enzyme levels in blood. Blood samples were also taken from not operated rats to act as a base line value.
At the end of the experimental period of each sub group (4, 8 and 12weeks), the rats were terminated. The surgically defected mandibles were dissected out and subjected to:
1-Radiodensitometric analysis to determine the radiographic bone density of the surgical defect throughout the healing process
2-Histological examination: Hematoxyline and Eosin (H&E) stain using Light microscope.
3-Histochemical examination: Masson Goldner trichrome using Light microscope.
Examination of the H & E stained sections of the mandible of Sub group IIA showed minimal bone formation from the defect margin. The newly deposited bone trabeculae were apparently reduced in both thickness and extension in comparison with subgroup IA.
Numerous dilated blood vessels congested with red blood cells (RBCs) and inflammatory cells infiltrations, were encountered in marrow spaces as well as the connective tissue.
In subgroup IIB, the H & E stained sections of the experimental defects showed increase of the bone formation from the defect margin. The newly formed woven bone exhibited irregular bone trabeculae with wide marrow cavities.
Apparent Line of demarcation between new and old bone was obvious which was hardly detected in subgroup IB. The blood vessels appeared normal with no congestion and few inflammatory cells were sometimes encountered.
Scattered Osteoblasts lining the bone trabeculae and the marrow cavities were detected. Osteocytes appeared relatively large in size with darkly stained nuclei and surrounded by lacunae of variable size and shape.
In subgroup IIC, the H& E stained sections revealed an almost uniform definite band of lamellar bone with frequent resting lines, in the most peripheral part of the bony defect. A definite reversal line between new and old bone was obvious. The center of the defect was filled by a considerable amount of spongy bone. The marrow cavities appeared narrow and lined by osteoblasts.
The Masson trichrome stained sections subgroup IIA showed few newly formed collage fibers bundles lining the defect wall, while the rest of the defect was apparently filled with numerous collagen fiber bundles. In subgroup IIB, the amount of newly formed collagen fibers increased, moreover, most of the marrow spaces showed new collagen fibers. Finally in subgroup IIC, the masson trichrome stained sections presented a considerable amount of green collagen fibers while the old collagen and the new mineralized bone appeared red.
The average (mean) percentage of radiographic bone densities of the surgical defect in sub group IIA was 48.38 % of that of the normal bone, increased to 80.27 % in subgroup IIB and then slightly raised to 82.06 % in subgroup IIC.
The serum amylase level in subgroup IIA was less than the normal value, it was slightly increased in subgroup IIB and finally in subgroup IIC, the serum amylase level was slightly more than the normal value. However, the serum calcium level was within the normal value in all experimental and control subgroups.