The Study Of Cell Proliferation,apoptosis And Apoptosis Related Genes By Five Different Prosthodontics Materials On Fibroblast Cells

Dental ceramics had good biocompatibility, excellent aesthetics, stable colour, little plaque build-up, low thermal conductivity and other properties. It couldn't be replaced by other prosthodontics materials such as metal and plastic. It could produce the past simple inlay, veneer to the development of crown, fixed bridges, even the upper structure of implant. Our group developed a new type of dental machinable ceramic based on diatomite, which added nano toughening agent(nano zirconia dioxide, alumina dioxide, titania whisker, etc.) to improve its strength. Co-Cr alloy porcelain, Ni-Cr alloy porcelain and resin were also the common clinical prosthodontics materials. However, metal alloys were reported that they had some bad impacts to life if they applied to the internal physiological environment of body. Biocompatibility evaluation was a important part of medical metal materials.In this study, five prosthodontics materials biocompatibility was evaluated from the perspective of cell biology and molecular biology. The main purpose was to evaluate their biocompatibility by cell culture, MTT assay, flow cytometry to detect cell proliferation, cell cycle and cell apoptosis . And detection of Bcl -2 and Bax mRNA expression of five prosthodontics materials to explore the mechanics of cell apoptosis by RT-PCR, which provided a theoretical basis of a new index to evaluate biocompatibility. Test I The evaluation of proliferation on L929 cells by five different prosthodontics materialsObjective: To identify the cytotoxicity of a new type of diatomite-based machinable ceramic and preliminary evaluate its biocompatibility in contrasted with other prosthodontics materials.Method: In the present study, MTT was used to assess the cytotoxicity of the new ceramic, comparing to other four prosthodontics materials. The cell line (L929) were treated with extract dilutions of the five prosthodontics materials for 1d, 3d, 5d. In order to observe the changes in cell morphology, measure absorbance (OD value) to calculate the relative cell proliferation rate (RGR), and determine the cytotoxicity grade.Result: MTT method found no significant difference in the cell viability among control, new ceramic, pressable ceramic and Co-Cr alloy-porcelain (P>0.05). However, the cell viability of Ni-Cr alloy-porcelain and resin were higher than control (P<0.05). The cytotoxicity of all the materials was grade 1. Conclusion: All the prosthodontics materials had no apparent cytotoxicity to L929 cell.Test II Induction of cell cycle by five different prosthodontics materials on fibroblast cellsObjective: To evaluate a new type of diatomite-based machinable ceramic biocompatibility by studying its cell cycle on L929 cell in contrasted with other four prosthodontics materials. Methods: L929 cell line was treated with elutes of five materials including diatomite-based machinable ceramic, resin, pressable ceramic, Co-Cr alloy -porcelain and Ni-Cr alloy-porcelain. Flow cytometry tested cell cycle progression Result: The experimental groups had no statistical significance to the negative group (P>0.05).Conclusion: All the five prosthodontics materials had no special influence on cell cycle, which were consistent with the clinical application of the basic requirements of biocompatibility.Test III Induction of apoptosis by five different prosthodontics materials on fibroblast cellsObjective: To evaluate a new type of diatomite-based machinable ceramic biocompatibility by studying its induced apoptosis on L929 cell in contrasted with other four prosthodontics materials.Methods: L929 cell line was treated with elutes of five materials including diatomite-based machinable ceramic, resin, pressable ceramic, Co-Cr alloy -porcelain and Ni-Cr alloy-porcelain. Flow cytometry tested induced cell apoptosis. Annexin V-FITC/PI apoptosis staining kit quantitative detected cell death patterns.Result: Apoptosis rates of the new ceramic and prssable ceramic were low, and closed to the negative group(P>0.05). Apoptosis rates of other groups were much higher than the negative group. The major cytopathic effect of the new ceramic was time-dependent apoptosis. The apoptosis rate of resin was the highest, and the cell necrosis level of resin was also significantly increased, which had significant difference to the new ceramic(P<0.05). Conclusion: The five prosthodontics materials had some differences on apoptosis level. Apoptosis might become a new method of evaluating material's biocompatibility.Test IV Induction of apoptosis related genes by five different prosthodontics materials on fibroblast cellsObjective: To evaluate a new type of diatomite-based machinable ceramic biocompatibility by studying its induced apoptosis related genes on L929 cell in contrasted with other four prosthodontics materials.Methods: L929 cell line was treated with elutes of five materials including diatomite-based machinable ceramic, resin, pressable ceramic, Co-Cr alloy -porcelain and Ni-Cr alloy-porcelain. Bcl-2 and Bax mRNA expression were determined by PT-PCR. Result: The Bcl-2 and Bax mRNA levels of the new ceramic and the pressableceramic group were closed to each other, which had no statistical significance to the negative group(P>0.05). The Bax mRNA expression of resin was the highest, and the Bcl-2 mRNA expression was the lowest, which had significant difference to the new ceramic(P<0.05). And Co-Cr alloy -porcelain group and Ni-Cr alloy-porcelain group had statistical difference to the negative group(P<0.05).Conclusion: The five prosthodontics materials had some differences on the level of apoptosis related genes. Detecting apoptosis related genes might become a new method for evaluating material's biocompatibility.