Study On Properties Of Nano-silver Modified Denture Base

ObjectiveThe aim of this study was to study the mechanical properties,longlasting antimicrobial ability and cytotoxicity of nano-silver modifiedpolymethyl methacrylate (PMMA) denture base resin,providing atheoretical basis for the clinical application of modified dental PMMAmaterials.MethodsThe silver nanoparticles(AgNPs) coatings were deposited on thesurface of the PMMA denture base resin by magnetron sputteringtechnology for surface modification.According to different sputteringtime, the experimental samples were divided into4groups, PMMA group(denture base control group),PMMA-AgNPs10s group,PMMA-AgNPs40s group and PMMA-AgNPs80s group, respectively.Besides,there werealso blank control group, negative control group and positive controlgroup in cell toxicity experiment.Cross-cut test according to theinternational standards ISO2409：2007is adopted to detect the adhesionstrength between the coating and substrate.The contact angle of eachspecimen was investigated following the method of static droplets. Inaddition, the flexural strength was measured with three-point bending test.The prolonged antimicrobial activity against Candida albicans wasinvestigated following a method according to the Japanese standardsJISZ2801-2000after submersion in deionized water over1month,3month and6month,respectively.After6months,samples were taken out for the MTT assay on mouse fibroblasts cell line L929.ResultsAdhesion results showed that adhesion level of each specimen weregrade0.According to the results of one-way ANOVA of contact angle andflexural strength,there was statistically difference in the PMMA-AgNPs80s group,compared to control, whereas the PMMA-AgNPs10s andPMMA-AgNPs40s group did not.The antimicrobial rate of thePMMA-AgNPs10s and PMMA-AgNPs40s groups dropped significantlywith the extension of storage time,whereas the PMMA-AgNPs80s groupremained100%.MTT results showed that L929cytotoxicity of theexperimental group and the negative control group materials were grade0,whereas the positive control group were grade4.No statisticaldifference in absorbance value was observed between the experimentalgroup and the negative control group materials. However, for the positivecontrol group, there was a significant difference between them.ConclusionsThe coatings of each group combined well with PMMAsubstrate.The surface wettability of each specimen did not changeobviously,thus the hydrophobicity of the PMMA-AgNPs80s groupincreased slightly.For the flexural strength,all groups of the specimenswere accord with national standard.After long-term immersion,there wereno cytotoxicity of each experimental sample on mouse fibroblast cellline,while the PMMA-AgNPs80s group exhibited excellent long-termantimicrobial property against Candida albicans.