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@#Silicon nitride has high fracture toughness and compressive strength similar to human bone. It meets the basic mechanical requirements of implants and has good biocompatibility. The micrometer/nanometer morphology surface characteristics of silicon nitride give it good osteogenic activity and antibacterial properties, which are helpful to reduce the incidence of periimplant inflammation. Therefore, silicon nitride has good application potential in dental implants. In orthopedics, silicon nitride implants have been used in spine repair and joint implantation. However, there is a lack of research on silicon nitride as dental implant material. The evaluation of the osteogenic and antibacterial properties of silicon nitride bioceramics prepared using different sintering additives and sintering processes, the antibacterial properties of silicon nitride on different dominant oral pathogens, and the osteogenic activity and antibacterial properties of silicon nitride materials implanted into the jaw need to be further studied. Combined with the latest research results at home and abroad, this review discusses the application potential of silicon nitride materials in dentistry.
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Objective: To detect the optimal fusing temperature, the fusing time and the best filler ratio of α-Si3N4 and SP1SiO2, and to clarify their influence in the properities of dental resin composites. Methods: The α-Si3N4 crystalline were mixed with SP1SiO2 particle at the ratio of5:l (Wt%), and then were sintered under 500°C, 650°C, 800°C, 950°C and 1 100°C at a rise rate of 250 · h-1 and maintained for 10 min, 30 min and 3 h, respectively (used as α-Si3N4-SP1SiO2 groups). SP1SiO2 particle, α-Si3N4 crystalline, mixed and non-fused α-Si3N4 and SP1SiO2 (mixed) groups were set up, and two commercially available resin composites were selected and used as control groups. And they were fully mixed with the resin matrix in 60% (Wt%) after the treatment of cyclohexane solution to make the samples. The flexural strength of specimen was tested and the morphology of section under SEM was analyzed. Then α-Si3N4 was mixed with SP1SiO2 in a ratio of 2; 1. It was fused under the optimal fusing conditions. After the treatment of cyclohexane solution, it was mixed and polymerized with the resin matrix in the proportions of 20%, 40%, 60%, 70% and 75% (Wt%), and two kinds of commercially available resin composites were selected and used as control groups. The flexural strength of specimens was tested and the morphology of section under SEM was analyzed. Results: The maximum flexural strength value in α-Si3N1-SP1SiO2 groups was at 800°C and 30 min (P>0. 05); the flexural strength value was significantly higher than those in SP1SiO2 group, α-Si3N1 crystalline group, mixed group and two control groups (P<0. 05), and the morphology of section SEM was consistent with the mechanical properties. The flexural strengths of resin composites were increased gradually with the increasing of filler ratios of α-Si3N4 and SP1SiO2 fusion from 20% to 60% (P<0. 05); the flexural strength values of resin composites with the proportion of 60%-70% were not increased significantly, the flexural strength values of resin composites with the proportion of 70%-75% were decreased, and the flexural strength values of the resin composites with the proportion of 60% and 70% were significantly higher than those of resin composites with the proportions of 20%, 40%, 75% and control groups; the morphology of section under SEM was consistent with the mechanical properties. Conclusion: The optimum fusing condition for α-Si3N4 and SP1SiO2 is 800°C for 30 min, and the best filler ratio of α-Si3N4 and SP1SiO2 is 70%.
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Trace impurities of Al, Ca, Co, Fe, K, Mg, Mn, Na, Ni in silicon nitride powder were determined by slurry introduction into a solution-cathode glow discharge-atomic emission spectrometer (SCGD-AES).The effect of particle size on the stability of suspension was investigated.A 6-port valve was selected to link sampling system and SCGD-AES, by which the suspension could be introduced into the SCGD-AES to get instantaneous spectrum signal.The calibration curves for quantitative analysis could be established using aqueous standards and the pH of suspension was not required to be adjusted accurately.The applied voltage, solution flow rate, and integral time of PMT were set to 1080 V, 1.2 mL/min and 800 ms, respectively.In this work, slurry sampling was combined with SCGD-AES by a 6 port 2-pos valve.Powder Si3N4 was tested by this way and the limits of detection for all nine elements were 0.2-53.0 mg/kg.The RSDs were 1.1%-5.0%.The detection result of trace impurities in standard reference material ERM-ED101 agreed with that obtained from inductively coupled plasma atomic emission spectrometry.This method was proved to be accurate, reliable and valuable.