The Expression And Significance Of The Three Kinds Of Isoforms Of NOS In Periodontal Tissue During Orthodontic Tooth Movement

Objective: Nitrtic oxide (NO) is a strong free radical gas, a small molecul Medium, which has been paying more close attention recently. It releases in the process of ornithine cycle in which L-Arg converts into carbamidine amino acid with Nitric oxide synthase (NOS) and has many physiological and pathological functions including information convection, neurotransmitter, inflammatory reaction, vascular dilatation. However, Nitric oxide has two edges.The normal concentration of NO has physiological function of protecting normal tissues.More and less concentration have pathological roles by impacting on the tissues or organs. NOS has three kinds of isoforms including endothelium nitric oxide synthase (eNOS), neuous nitric oxide synthase (nNOS) and intrinsic nitric oxide synthase (iNOS). Both eNOS and nNOS are called cNOS. There were already many reports of NO in other subjects in 1980s. In 1993 Bodis succeeded in detecting NO from saliva. So the study of NO developed quickly in dentistry involving oral medicine, surgery, orthodontics,prodontics and so on. However, the function of how NO and NOS changed and worked during orthodontic tooth movement has not been reported in our nation. This experiment released the function of NO and NOS in orthodontic tooth movement by establishing SD Rat model, detecting the changes of three kinds of NOS expression with immunohistological means in orthodontic tooth movement. Reserching the mechanisms of NO and NOS played in orthodontic tooth movement and knowing about the changes of all kinds of NOS in periodontal tissue have important meaning in improving tooth movement, shorting the process of orthodontic treatment and restraining the malignant absorption of the cementum and alveolar bone by using pharmacological or other methods. Methods: 1.Building rat models by treating it with orthodontic toothmovement: In the way of statistic, grouped the SD rat into five groups randomly, 5 in one group, and based on the Method from reference document. To anesthesia the rat, linkage the elastic spring between the left first molar and the central incisor to realize the relative movement of the teeth. 2.Clinical observation: Measure the space between the first molar and the central incisor by slide gaud before exertion. Then calculate the space changed of the tooth after the exertion. 3.Collection: Treat the rat's teeth with the power of 60g, then put the rat into death by heart injection with 4% citromint after 0, 1, 3, 7, 14 days. Get the maxillary bone, infiltrate it into 4% citromint, at 4℃,for 24 hours. Put it into 10% EDTA solutions for decalcification.4.Histology Observation: Make constitution sections, stain with HE, observe the changing of the periodontium during orthodontic tooth movement. 5.Nitric oxide synthase (NOS) detection: After decalcification, get the first molars and periodontium tissues, detect the expression of iNOS, eNOS, nNOS in the way of immunohistological techonology (the immunity test Kit was made in Bei Jing zhong shan biology limited company ) . 6.Statistic analysis: Using the beihang image analysis system to analyse the constitution section, expressed area and calculate the cell number. Then do statistic analysis with the statistic system made in the fourth army medicine university. Results: 1.Clinical observation and statistic analysis results showed that the speed of tooth movement is quick in the first three days, after this period the speed of movement will be slower gradually. 2.HE Staining: 0 day after the exertion it shows that the periodontal ligament is well-distributed, there are few of absorbed lacunas in the alveolar bone. 1 day after the exertion the periodontal ligament being dragged had hemangiectasiaed, the periodontal ligament being pressed had narrowed, osteoclast had been differentiation. 3 days after the exertion, both sides of being dragged and being pressed were found a lot of absorbable lacunas, the number of osteoclast increased. 7 days after the exertion, the number of osteoclast began to decrease, fibroblastand osteoblast are active. It is obviously to detect hyperplasia in the side of being dragged. After 14 days the transitional bone and desmodontium appeared, osteoblasts arranged in lign,the periodontal ligament is well-distributed. 3.eNOS expression: 0 day after the exertion, a few of osteoclasts and individual angioepithelial cells could express occasionally. 1 day after the exertion, the eNOS expression increased, such as the epithelial cells of blood vessel ,the osteoclasts and a part of fibroblasts. 3 days after the exertion, there are high expression for endoepithelial cells of blood vessel, fibroblasts, osteoblasts etc. 7 days after the exertion, the expression in all kinds of cells is decreased. 14 days after the exertion, the number of the osteoclast is decreased and eNOS expressed slowly. There are only a few osteoblasts and interstitial cells can be expressed. 4.iNOS expression: In the specimen without exertion, all kinds of cells did not express at all. 1 day after the exertion, the osteoclasts, epithelial cells, fibroblasts showed some expression. 3 days after the exertion, all kinds of cells expressed strongly. After 7 days the expression had decreased obviously. When it was the 14th day, there are a few of cells can express but weakly. 5.nNOS expression: 0 day after the exertion, there are a few of cells can express around the blood vessel of the periodontium. There are no difference between the 0 day and the 1 day. At the 3rd day, osteoclasts and some interstitial cellsexpressed. At the 7th day, nNOS in osteoclasts expressed less and the interstitial cells showed weakly expression. At the 14th day, there are only osteoclasts and a few interstitial cells show weakly expression. 6.It showed in the Statistic analysis result that the three kinds of the nitric oxide synthases expressed differently during different periods of the tooth movement. Conclusions: 1.It's the swif time in orthodontic tooth movement at the first three days, then it's the slow time following. 7 days later the periodontal tissues began to rebuild gradually. After 14 days, the circumstance of periodontal ligament trended towards balance gradually. 2.The expressed status of the three kinds of NOS changed with time in periodontal tissues during orthodontic tooth movement. It can be seen that the three kinds of NOS play roles in rebuilding of the periodontal tissues. 3.The three kinds of NOS expressed evidently in osteoclasts especially. It's approved that all the three kinds of NOS take part in mediating the function of the osteoclast. 4.eNOS expressed obviously at the early time of the tooth movement, it proved that eNOS may play an import role at the early time of the tooth movement. 5.The NO with high concentration maybe control the osteoclast 's absorbability and differentiation, at the same time, control the function of osteoblast for proliferation and evolving...