| Polymethyl methacrylate(PMMA)is a denture base material widely used in stomatology,of which room curing PMMA has the advantages of low price and easy operation,and is often used in the clinical production of orthodontic activity appliances,mandibular slope guide plates,denture relining,jaw cyst blockers,and pseudofusions.Room curing PMMA due to incomplete polymerization reaction can lead to rough and porous surfaces,which will promote the colonization of Candida albicans and cause denture stomatitis.Objective:In this experiment,RHA-I antibacterial agent and RHA-IF-II antibacterial agent were added to room curing PMMA,respectively,to compare their effects on the antibacterial properties and mechanical properties of room curing PMMA material,so as to provide experimental reference for the application of nano-silver loaded inorganic antibacterial agent in denture base.Methods:(1)The minimum bactericidal concentration of RHA-I antibacterial agent and RHA-IFII antibacterial agent on Candida albicans was detected by liquid dilution method.(2)RHA-I antibacterial agent was mixed evenly with PMMA powder to prepare antibacterial specimens,which were recorded as RHA-I group and divided into 0.25%RHA-I group,0.5%RHA-I group,1%RHA-I group and 2%RHA-I group according to the different content;RHA-IF-II antibacterial agent was mixed evenly with PMMA powder to prepare antibacterial specimens,which were recorded as RHA-IF-II group and divided into0.25%RHA-IF-II group,0.5%RHA-IF-II group,1%RHA-IF-II group and 2%RHA-IF-II group according to the different content.(3)The antibacterial rate against Candida albicans was measured by thin film adhesion method.(4)Universal testing machine and micro-vickers hardness tester were used to test the bending strength,elastic modulus and Vickers hardness of each specimen.(5)The specimen extracts of 0% group,2%RHA-I group and 1%RHA-IF-II group were co-cultured with mouse fibroblasts(L929)for 1 day,3 days and 5 days,respectively.The cytotoxicity of the extracts to L929 was determined by CCK8 kit.Results:(1)The MBC of RHA-I and RHA-IF-II antibacterial agents against Candida albicans was 0.625mg/ m L and 0.3125mg/ m L,respectively.(2)With the increase of antibacterial agent content,the antibacterial properties of the two room curing PMMA materials were gradually enhanced.When the content of RHA-I antibacterial agent was 2%,the antibacterial rate of the specimen reached 98.16%,showing antibacterial effect.When the content of RHA-IF-II antibacterial agent is 1%,the antibacterial rate of the specimen can reach 99.26%,showing strong antibacterial effect.When the content of antibacterial agent was the same,the antibacterial performance of room temperature cured PMMA with RHA-IF-II antibacterial agent was significantly improved compared with that with RHA-I antibacterial agent(P<0.05).(3)With the increase of antibacterial agent content,the bending strength,elastic modulus and Vickers hardness of the two kinds of room curing PMMA materials both increased first and then decreased.The mechanical properties of the 1%RHA-IF-II specimen were significantly improved compared with that of the 2%RHA-I specimen(P < 0.05).The Vickers hardness of the 1%RHA-IF-II specimen were significantly improved compared with that of the control group(P < 0.05).(4)Compared with the control group,specimen extracts from 1%RHA-IF-II group had inhibitory effect on cell proliferation(P < 0.05),while extracts from 0% group and 2%RHA-I group had no significant effect on the proliferation and activity of L929 cells(P> 0.05).By calculating the relative growth rate(RGR)of cells,it was found that RGR value was > 86.3%and cytotoxicity level was ?1,indicating good biosafety.Conclusion:Compared with RHA-I antibacterial agents,adding a lower content of RHHA-IF-II antibacterial agents to the room temperature curing PMMA material can achieve good antibacterial effect and relatively excellent mechanical properties. |
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