بررسي واكنش بافتي متعاقب استفاده از پيچ تايتانيوم به عنوان انكوريچ ارتودنسي در خرگوش

The study of tissue reaction following placement of titanium screws as an orthodontic anchorage in rabbits

The aim of this research was to study tissue reaction following placement of titanium screws and two types of loading, delayed and immediate in femoral bone of rabbit . The sample consisted of 14 male New Zealand rabbits. As a control group, 2 rabbits had surgical procedure and right lateral surface of femoral bone was drilled and two holes were made with 1cm distance. In the second group (4 rabbits), two titanium screws (3mm diameter, 7mm length) were placed with 1cm distance. In the third group (4 rabbits) 4 oz traction force was applied on screws by S.S. Closed Coil Spring that covered with polyethylene tube and it was considered as immediate loading group. The last group (4 rabbits) had two steps surgical procedure. In the. first step, screws were placed and after 8 weeks as healing period, screws were loaded as the mentioned third group. After two months samples were sacrificed and femur bones removed and fixed in 10% formalin. The results showed that there was not any displacement for all 24 screws and it was not statistically significant(P<0.001) which was tested with Paired t-test and Wilcoxon matched pairs. Similar histologic pattern included vital bone around the titanium screws and lack of inflammatory cells accumulation was seen using light microscope in all groups. Surrounding bone was of mature lamellar type. A thin layer of fibrous tissue(2-3 layers of cells) was seen between screws and interface. There was not any difference between histologic reaction of two immediate and delayed groups. According to the results of this study, an acceptable histologic compatibility exists between titanium screws and .surrounding hone and immediate loading is an acceptable method of orthodontic anchorage preparation which can eliminate healing period of delayed loading.