Effects On Liver And Kidney Affected By Digitized Metallic Dental Prosthesis: An In Vivo Study

Objective: Based on animal model of maxillary metal frameworks in beagle dog,the purpose of this study was to study the function,metal ions and biological effects on liver and kidney affected by two kinds of digitized metallic dental prosthesis,so as to provide experimental basis and guidance for the selection of dental prosthesis with different manufacturing methods in clinical works.Methods:(1)In this study,according to the random block method,9 beagle dogs were randomly divided into three groups: cobalt-chromium(Co-Cr)alloy group,commercially pure titanium(CP-Ti)group and blank control group.The Co-Cr alloy frameworks made by selective laser melting(SLM)and the CP-Ti frameworks made by computer numeric controlled milling(CNC milling)were fixed to the palate of beagle dogs to establish the animal model of maxillary metal frameworks in beagle dogs.Blood samples were collected at 0 day,3 days,1 week,2 weeks,1 month,2months,3 months,4 months,5 months and 6 months after wearing the frameworks.Automatic biochemical analyzer was used to detect the function of liver and kidney.(2)After the blood samples were collected at the 6th month,the beagle dogs were killed and the liver and kidney tissue samples were collected.After digestion of some tissues,the types and concentrations of metal ions in hepatorenal tissues of each group were accurately detected by inductively coupled plasma mass spectrometry(ICP-MS).(3)Some tissues were fixed and embedded into tissue sections,the histopathological changes of liver and kidney were detected by hematoxylin and eosin(H&E)staining.TUNEL assay(Td T-mediated d UTP nickend labeling)was used to detect the apoptosis level of liver and kidney tissue.By comparing the apoptosis rate of each group,the effects of different digitized metallic dental prosthesis on the apoptosis level of liver and kidney tissue were studied.(4)The protein was extracted from tissue samples,then the expression of autophagyrelated protein P62 and Beclin1 in liver and kidney were detected by Western blotting.By comparing the expression of target protein in each group,the effect of digitized metallic dental prosthesis on autophagy in liver and kidney was analyzed.Results:(1)The results of liver and kidney function test showed that there were significant differences in the level of liver and kidney function at different time points(P < 0.05),the wearing time and grouping were no interaction(P > 0.05),but there was no significant difference in the level of liver and kidney function among SLM Co-Cr group,CNC milled CP-Ti group and blank control group(P > 0.05).(2)ICP-MS detection showed that there was no significant difference in the type and concentration of metal ions in hepatorenal tissue between SLM Co-Cr alloy group and CNC milled CP-Ti group compared with the blank control group(P > 0.05).(3)The histopathology of liver and kidney in SLM Co-Cr alloy group and CNC milled CP-Ti group was not significantly abnormal,and there was no significant difference compared with blank control group.(4)TUNEL assay showed that the apoptosis rate of hepatorenal tissue in SLM Co-Cr group and CNC milled CP-Ti group was slightly higher than that in the blank control group,but the difference among the three groups was not statistically significant(P > 0.05).(5)The results of Western blot method showed that there was no significant difference in the expression of P62 and Beclin1 of hepatorenal tissue among SLM Co-Cr group,CNC milled CP-Ti group and blank control group(P > 0.05).Conclusions: During the experimental observation period,SLM Co-Cr alloy and CNC milled CP-Ti have no significant effect on function,metal ions,histopathology,apoptosis and autophagy in liver and kidney,and have good biocompatibility.