Study On The Corrosion And Adhesion Behavior Of Microorganism On Common Dental Alloys

Purpose:The objective of the study was to evaluate the corrosion properties of different dental alloys and the corrosion capability of different microorganism on common dental alloys,this study also aimed on the comparison of adhesion behavior of microorganism on non-microorganism-corroded and microorganism-corroded dental alloys in order to investigate the connection between microorganism corrosion and microorganism adhesion on dental alloys,thus providing new ideas for prevention of disease caused by corrosion of dental alloys.Methods:Experiment 1.The Co-Cr and Ni-Cr dental alloy specimens were immersed in Candida albicans solution,Streptococcus mutans solution and BHI culture medium for 8 weeks,using surface roughness tester,scanning electron microscope and electricalchemical workstation to test and compare the corrosion properties of the dental alloys.Experiment 2.The Candida albicans corroded Co-Cr,Ni-Cr dental alloy specimens and non-corroded Co-Cr,Ni-Cr dental alloy specimens were immersed in the solution of Candida albicans for 48hours;The Streptococcus mutans corroded Co-Cr,Ni-Cr dental alloy specimens and non-corroded Co-Cr,Ni-Cr dental alloy specimens were immersed in the Streptococcus mutans solution for 48 hours,then the adhesion amount of microorganism on each dental alloy specimen was tested by spectrophotometry,flat colony counting method and scanning electron microscope.Results:Experiment1:The corrosion properties of each group's dental alloys were tested by potentiodynamic polarization measurement,statistical analysis result showed that amongst Co-Cr alloy,Icorr??Acm-2?of Candida albicans corroded specimens?3.34±0.08?>Icorr of Streptococcus mutans corroded specimens?3.05±0.06?>Icorr of BHI culture medium corroded specimens?1.64±0.06?,P<0.05;Rp(M?cm^-2)of Candida albicans corroded specimens?3.10±0.04?<Rp of Streptococcus mutans corroded specimens?4.22±0.05?<Rp of BHI culture medium corroded specimens?6.28±0.03?,P<0.05.Amongst Ni-Cr alloy,Icorr of Candida albicans corroded specimens?7.55±0.07?>Icorr of Streptococcus mutans corroded specimens?3.40±0.08?>Icorr of BHI culture medium corroded specimens?2.10±0.04?,P<0.05;Rp of Candida albicans corroded specimens?2.19±0.04?<Rp of Streptococcus mutans corroded specimens?3.12±0.04?<Rp of BHI culture medium corroded specimens?5.52±0.04?,P<0.05,indicating that Candida albicans and Streptococcus mutans could cause microorganism corrosion on Co-Cr and Ni-Cr alloys,while Candida albicans showed stronger corrosion capability than Streptococcus mutans.Icorr of Ni-Cr alloys immersed in Candida albicans solution,Streptococcus mutans solution and BHI culture medium was higher than Icorr of Co-Cr alloys?P<0.05?,and Rp of Ni-Cr alloys was lower than Co-Cr alloys?P<0.05?,indicating that Co-Cr alloy showed better corrosion resistance compared to Ni-Cr alloy.The result of surface roughness test and scanning electron microscope test suggested that the surface roughness of Co-Cr and Ni-Cr alloy specimens increased when they were immersed in the solution of Candida albicans and Streptococcus mutans,indicating that the corrosion caused by Candida albicans and Streptococcus mutans could change the configuration of surface of Co-Cr and Ni-Cr alloys,increasing surface roughness of dental alloys.Experiment 2:Spectrophotometry results showed that OD of biofilm on Candida albicans corroded Co-Cr and Ni-Cr alloys was 0.066±0.004and 0.069±0.003,higher than non-corroded Co-Cr and Ni-Cr alloys?0.027±0.003;0.028±0.003?;OD of biofilm on Streptococcus mutans corroded Co-Cr and Ni-Cr alloys was 0.069±0.003 and0.067±0.004,higher than non-corroded Co-Cr and Ni-Cr alloys?0.029±0.002,;0.026±0.003?.Flat colony counting result showed that colony counting?10⁴CFU/L?of biofilm on Candida albicans corroded Co-Cr and Ni-Cr alloys was 258±18 and 264±18,higher than non-corroded Co-Cr and Ni-Cr alloys?134±12;126±8?,colony counting of biofilm on Streptococcus mutans corroded Co-Cr and Ni-Cr alloys was258±16 and 262±16,higher than non-corroded Co-Cr and Ni-Cr alloys?124±8;136±8?.Scanning electron microscope results showed that more microorganism adhered on Co-Cr,Ni-Cr alloys corroded by Candida albicans and Streptococcus mutans,indicating that the scale of microorganism adhesion on Co-Cr and Ni-Cr alloy increased when the specimens were corroded by Candida albicans and Streptococcus mutans,microorganism corrosion on dental alloys could furtherhance microorganism adhesion.Conclusion:Microorganism could cause corrosion on dental alloys,the scale of corrosion was affected by the species of microorganism and the consistence of dental alloys.Surface roughness of dental alloys increased after microorganism corrosion,thus enhancing the microorganism adhesion on the surface of these alloys.Microorganism corrosion and adhesion was closely interlinked and mutually reinforcing.