Effect Of Recasting On Biocompability Of The Nickel-chromium Ceramic Alloy

Objective: To study the effect of recasting in vitro cytotoxicity, haemolysis and oral mucous membrane irritation test of the Nickel-Chromium Ceramic Alloy.Methods:(1)According to ISO 10993-5:1999 standards, the Nickel-Chr- -omium Ceramic Alloy was recasted by 1 to 5 times to make cylinder test specimens with 4.0cm diameter and 8.0mm high, then in vitro cytotoxicity test (MTT method)on L-929 cell were carried on to evaluate the cytotoxicity of each specimen. And analysis the results between the specimens which were recasted 2 to 5 times with the specimens which were casted by 1 time. (2)According to ISO/TR 7405-1984 standards, Nickel-Chromium Ceramic Alloy was recasted by 1 to 5 time to make the wafer test specimens with 5.0mm diameter and 1.0mm thick, and to test the haemolysis of each specimen, then to analysis the absorbance between the specimens which were recasted 2 to 5 times and the specimens which were casted by 1 time.(3)According to the ISO/TR 7405-1984 standards,Nickel-Chromium ceramic alloy was recasted into wafer with 5.0mm diameter and 0.5mm thick by 1-,2-,3-,4-,and 5-time,the wafer were fixed to the oral mucous of golden hamster, then observe the changes of oral mucous membrane after 14 days.Results:(1)The level of cytotoxicity of all the experimental groups were ranged from 0 to 1. No statistically differences were found on the absorbance in different leaching liquid, between the specimens fabricated by 2-,3-,4-,and 5-time casting and the 1-time casting specimens(p>0.05).(2)Haemolysis rates of the recasted five times Nickel-Chromium ceramic alloy were 1.264%,1.205%,1.170%,1.300%,1.323%.No statistically differences were found on the absorbance between the specimens fabricated by 2-,3-,4-,and 5-time casting and the 1-time casting specimens(p>0.05).(3) There was no abnormal reaction on local mucous membrane such as hyperaemia, haemorrhage, erosion, or ulcer, which touch with the specimens recasted by 1-,2-,3-,4-time and the negative control group. But there were obvious red and swollen, inflammation, abscess of the oral mucous membrane which touch with the specimens recasted by 5-time and the positive control group. The tissue slices of oral mucous which touched with specimens recasted by 1-,2-,3-,4-time and the negative control groups showed: the epitheliums were complete, the permutations were well distributed, there were no inflammatory cell. the tissue slices of oral mucous which touched with specimens recasted by 5-time and the positive control groups showed: the epitheliums were incomplete, the permutations were disorder, there were inflammatory cell, vascular engorgement, and abscess-formation.Conclusion: It is preliminarily estimated that the Nickel-Chromium Ceramic Alloys which were recasted by 1-,2-,3-,4-time, have good biocompatibility, and the nickel-chromium ceramic alloy which was recasted by 5-time, doesn't have good biocompatibility.