| As we know, the replantation of tooth has a long history. But the lose of the activity of periodontal ligament cells and root replantation has influenced the successful rate of tooth replantation for a long time. People are devoted to discovering new methods to be more successful.In recent years, abroad scholars applied enamel matrix proteins (EMPs) in the therapy field of periodontology, which the result is quite inspiring. Studies have shown EMPs can promote the regeneration of periodontal tissues and this kind of regeneration is similar to the physiological status of periodontal attachment apparatus. Even though the mechanism that EMPs induces periodontal tissue regeneration is unclear, its function of promoting tissue reestablish in treating defecting of periodontal tissue has been proved. It has been showed that EMPs isn't only related to the development of enamel, but also closed to the occurrence of cementum, such as inducing the formation of accellular cementum. It could affect the biological function of multicell culture, too. For example, it can promote the proliferation of periodontal ligament cells, increase the total amount of protein that excreted by periodontal ligament cells, promote periodontal ligament cells to formbiomineralization, promote the differentiation osteoblast cell, but inhibit the proliferation of epithelial cells. It has also been found that EMPs posses bacteriostasis. These results supplys the basic theory for EMPs to be used in the regeneration of periodontal tissue.The studies on EMPs at home and abroad are concentrated in treating periodontology and it's mechanism. But the study on the influences of EMPs on the healing of tooth replantation is few abroad and nearly none at home. The aim of this research is to study whether EMPs could promote the regeneration of periodontal tissue on the replanted tooth, and to find a new method to improve successful rate of tooth replantation.We extracted EMPs from porcine tooth germ, and identified its biological activity, then observed some important effects of EMPs on the periodontal ligament cells through improved cell culture technique. After that, we applied EMPs in SD rat's tooth replantation. We watch the tissue recovery of replanted tooth through sections, and analysis the functions of EMPs on the recovery of replanted tooth. The methods and results of every experiment are as followed:1. Extraction of EMPs and measuring of molecular weight: Dissected teeth germ from fresh jaws of porcine with 6 monthes, andthen we scraped them to obtain the unmineralized enamel matrix. After that, EMPs was extracted by acetic acid method. The proteins we got showed typical molecular weight distribution of amelogenin through SDS-PAGE. That is to say, the collected molecular weight distribution concentrated in 20kDa, 13kDa and smaller.2. Identification of EMPs:We establish PDL cells culture model in vitro by improved cell culture technique and then chose the proliferation ability of PDL cells as index of biology activity of EMPs. Cell proliferation with varied concentration of EMPs or without EMPs was assessed by MTT method. The results showedthat 50mg/l MEPs could promote PDL cells proliferation signigicantly, and the concentration with the most effect was 100mg/l. These results suggested that the EMPs was extracted had good biology activity.3. Study about the effect of EMPs on the healing of periodontal tissue of replanted toothThe EMPs extracted was used in the process of tooth replantation of rat. The methods of tooth replantation consist of immediately replantation, delayed replantation and replantation without PDL. Set up blank control group respectively. Collected samples at 2 weeks and 4 weeks after operation. Through observing the sections and ground sections to study the resorption on the surface of roots. Calculate the root resorption rate of the replanted tooth and the rate of surface resorption, inflammatory resorption or replacement resorption. Analysis the effection of EMPs on the healing of periodontal tissue...
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