| Malocclusion is a kind of common disease in Department of Stomatology,. It affects not only chewing, language, and other functions, but also affects appearance, interferes with sociality and individual physical and mental growth. With the development of society, the improvement of people’s living standard, and the popularization of oral medicine knowledge, people’s pursuit of beauty is getting higher and higher, the demand for correction of malocclusion becomes bigger and bigger. Orthodontic can correct most malocclusions, improve patients’face type by applying orthodontic force on dislocated teeth and jaws,so, more and more people prefer orthodontics. Root resorption is a common clinical complications,almost orthodontic patients, Root resorption can affect the stability and health of teeth and have a negative impact on orthodontic treatment and stability.so how to avoid、reduce root absorption have becomed the topic of growing number of scholars. Smoking is an important risk factor for periodontitis, as a result, smokers suffer a higher morbidity and frequency of tooth loss, more serious symptoms, faster progression of sickness, poorer prognosis and responding worse to treatments. Nicotine, the main alkaloid in tobacco smoke, can damage the periodontal tissues directly through impeding the normal function of the periodontal immune system. In this study,firstly an experimental animal.In my experiment, we want to investigate effects of Nicotine, And compare with the saline group.Through this way we want to find if Nicotine can really increase the rate of tooth movement, so we can provide experimental basis for clinic OTM.Objective:To investigate the influence of Nicotine on orthodontic tooth resorption in rats through observing tooth movement distances, the number of cementoclasts, the expression of ODF and root resorption degree.Methods:36male8weeks old Wistar rats((180-200g) were chosen, Every rat maxillary divided into experimental and control sides. Then the animal model for orthodontic tooth movement of rats was established, the nickel-titanium(Ni-Ti) closed coil springs initially generating an average force of60g were inserted in each rat’s mouth between the bilateral upper first molar and incisor, keep the force about60g.the experimental side:Inject0.5mg/kg Nicotine solution about0.1ml.the control side:0.9%NS.6rats were killed separately on3,7,14days in every side, separate the rat skull and measure the molar moved, produce periodontal tissue sections of the maxillary first molar,eaconh tooth make10sections, immunohistochemistry and HE all sections Observe the number of cementoclast through the expression of ODF observing osteoclast; Finally all data were made statistical analysis. Observe root pressure side of periodontal tissue and root surface under an optical microscope and break cementum osteoclast cell number and morphological changes, and morphological changesand ODF (osteoclast differentiation factor) positive cells, trace point in the rat first molar root absorption zone boundary and boundary Respectively, process every experimental teeth single tissue sections through computer, measuring its near surface lacunae in the number, length, depth, calculate the length of root resorption Index (index=length of root resorption lacunae length of the root and/root total length).Results:1. the moving distance of the first molar (Table1, Figure5)Two tooth movements from experimental animals increased by time increased.Through a comparative analysis between the groups available, no significant difference (P>0.05) in the experimental tooth movement in day3, the experimental group and the control group of rats; in day7, the experimental rats tooth movement distance greater than the control group, the difference was statistically significant (P<0.05); in day14, tooth movement in rats from the experimental group than the control group, the difference was statistically significant (P<0.05).2. root resorption index (Table2)With the extension of the time of the afterburner, root resorption index showed an increasing trend.In day3, the experimental group and the control group were less root resorption index, showed no significant difference (P>0.05) between the two.In day7, the experimental group was bigger than the control root resorption index, there was a significant difference (P<0.05) between the two groups; In day14, the experimental group was bigger than the control root resorption index, there was a significant difference between the two groups(P<0.05).3. ODF optical density values (Table3)At each time, analyze the pressure side of periodontal tissue and root surface expression of ODF mean optical density from Experiment and control groups with image analysis software IPP6.0, and found that the expression of ODF increases with time and gradually increased. In day3, ODF expression of the experimental group was less than the control group, between two groups, difference was not statistically significant (P>0.05); in the7th day, the ODF expression in the experimental group was more than the control group, the difference was statistically significance (P <0.05); in day14, the expression of ODF experimental group was less than the control group, compare the two groups, the difference was statistically significant (P <0.05).4. The number of broken cementum cells (Table4, Figure6)With the extension of the afterburner time, in two groups, the number of broken cementum cells showed an increasing trend. In the3th day, there are a little of number of cementum cells, between two groups, difference was not statistically significant (P>0.05); In the7th day and14th day, there are more broken cementum cells in experiment group than control group, comparing two groups, the differences were statistically significant (P<0.05).Conclusions:①Nicotine can accelerate the speed of orthodontic tooth movement; ②Nicotine can increase the number of broken cementum cells at the pressure side, promoting periodontal tissue expression of ODF;③Nicotine can aggravate root absorption in the course of orthodontic. |
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