Biocompatibility Of A New Medical High-nitrogen Nickel-Free Austenitic Stainless Steel Detected By RT-PCR

ObjectiveVarious forms of corrosion would develop when dental alloys functions in mouth.Cytotoxicity is one of the most important problems in medical metal materials. BIOSS4 is a new kind of metal materials, developed by Institute of Metal Research,Chinese Academy of Sciences. The material's excellent mechanical property has been validated by mechanics experiments, but its biocompatibility still need further research.The effects of new medical BIOSSN4 and the other four kinds of alloys to L929 cell was compared by RT-PCR method. Through the comparison, we further evaluate BIOSSN4's biocompatibility.Materials and MethodsFive kinds of metal alloy is made into the radius of 5mm, lmm thick cylindrical metal;The Sheet Metals are placed in RPMI 1640 cell medium containing 10%fetal calf serum in the incubator of 37℃and 5%CO2 for seven days;L929 cells are cultivated and passaged with RPMI 1640 cell medium containing 10%fetal calf serum in the incubator of 37℃and 5%CO2;L929 cell was cultured with 5 dental alloys' leaching liquor and their negative controls for 48 hours,and then detect the mRNA empression of cells'caspass-3,caspass-9.Result5 alloy extracts and negative control group were cultured L929 cells caspase-3 and caspase-9 RNA expression as follows:In which the apoptosis rate of Au alloy group is minimum, and compared with the negative control group was no significant difference (P>0.05). Nickel-free austenitic stainless steel BIOSSN4 group induced apoptosis rate was slightly higher than the Au alloy group, but no significant difference (P>0.05). Nickel-free austenitic stainless steel BIOSSN4 group was slightly lower than the cobalt-chromium alloy, no significant difference (P>0.05). The apoptosis rate of other groups were significantly different between each other's(P<0.05).The apoptosis rate of nickel-chromium alloy is higher than the negative control group's (P<0.05).In these alloys, the order from low to high:negative control group,Au alloy, no nickel austenitic stainless steel BIOSSN4,Co-Cr alloy;317L austenitic stainless steel;nickel-chromium alloy.ConclusionsMetal ions of 5 dental alloys may induce cell apoptosis by different degree throuth mitochondrion pathway;The mRNA levels of caspase-3 and caspase-9 were as follows from low to high:negative control group, Au alloy, no nickel austenitic stainless steel, Co-Cr alloy,317L austenitic stainless steel, nickel-chromium alloy; no nickel austenitic stainless steel BIOSSN4 have good biological compatibility, and better than 317L stainless steel and nickel-chromium alloy.