Preparation Of Ag Coating On Stainless Steel Brackets And Experimental Study On Antibacterial Activity Of Streptococcus Mutans

Objective: To make the surface modified stainless steel and bracket with Ag coating andassess the antibacterial properties of Ag coating against Streptococcus mutants in vitro fororthodontic application.Method: Surface modification of stainless steel was carried out by the radiofrequency(RF) magnetron sputtering method with Ag, which then was melted by irradiation of highcurrent pulsed electron beam (HCPEB). The specimens were divided into three test groups withdifferent sputtered times and irradiation pulses. The control group which had uncoated stainlesssteel was employed to compare the results of other experimental groups with coated stainlesssteels. All the three groups were tested by the pellicle-sticking method for the assessment ofantibacterial properties of Ag coating against Streptococcus mutants. Then Ag coating onstainless steel brackets were make by conditions of the best inhibition percentage stainless steelof Ag coating.The crystal structure and surface morphology of the film were characterized byscanning electron microscopy and EDS. The morphology of Streptococcus mutants on the Agcoating stainless steel brackets live24h were characterized by scanning electron microscopy.Software package SPSS17.0was used for all statistical analysis．Results： The best inhibition percentage was99.30%for stainless steel with Agcoating which carried out by the radiofrequency (RF) magnetron sputtering15min and meltedby HCPEB50pulses. Streptococcus mutants on the Ag coating stainless steel brackets werebroken and living cells were not found.Conclusion： Stainless steels and brackets coated with Ag has shown significantantibacterial effect against Streptococcus mutants, which would cause dental caries. Surfacemodification of stainless steel orthodontic brackets with Ag coating can be used to prevent theaccumulation of dental plaque and the development of the white spot lesions (WSLs) duringorthodontic treatment.