| Silicone elastomer is a maxillofacial prosthetic material. It is used to make facial prosthetic appliance and obturator in clinic. Candida albicans sticks to silicone elastomer easily because silicone elastomer is porous and it will cause denture stomatitis of patients and increase the ageing of silicone elastomer.In recent years, inorganic antibacterial agents are used widely. As a new antibacterial material, nano- TiO2 is used in plastic, ceramic and cosmetic industry. Nano- TiO2 is a photocatalytic material. Under light, nano- TiO2 produces hydroxyl radicals. Hydroxyl radical is highly toxic toward microorganism. Nano- TiO2 is catalyst during the process of killing bacteria, so it doesn't decrease. It can kill many kinds of organisms .The duration of its photocatalytic effect can be long lasting and nano- TiO2 is safe. Thus nano- TiO2 is used in dentistry .This study was aimed to compare the antibacterial effects of nano-silver base antibacterial agent and nano-TiO2 antibacterial agent. Then antifungal agents were added into silicone elastomer, the most suitable antifungal agent was selected. Then the antimicrobial effect of silicone elastomer was examined after adding the selected antibacterial agent. Finally, the mechanical function of silicone elastomer was examined after adding antibacterial agent. The results were shown below:1 Four kinds of antibacterial were selected. There were two nano-silver base antibacterial agents and two nano-TiO2 antibacterial agent. Their Minimal Bactericidal concentration (MBC) against Candida albicans was determined by Liquid Dilution method. The MBC of two kinds of nano-silver base antibacterial agents were 40mg/mL .When the concentration was 20mg/mL, the number of recovered viable bacteria of one kind of nano-TiO2 antibacterial agent was considerably less than that of the control group,while the other was 40mg/mL. Nano-silver base antibacterial agents and nano-TiO2 antibacterial agents both had fine antibacterial effect against Candida albicans, and the effect of nano-silver base antibacterial agents were better than nano-TiO2 antibacterial agents.2 Four kinds of antibacterial agents were added into A-2186 silicone elastomer. The incorporating percentages were 0.5%,1.0%,1.5%,2.0%(W/W) .Then the silicone elastomer weren't solidified except nano- TiO2 antibacterial agents without silver.3 Nano-TiO2 was added into A-2186 silicone elastomer, whose incorporating percentage was 0.5%,1.0%,1.5%,2.0%(W/W) .Nano- TiO2 was not added into the control group. Then the antibacterial effect of the A-2186 silicone elastomer was determined by the film contact method with light and in the dark. Either with light or in the dark, the A-2186 silicone elastomer containing nano-TiO2 had the antibacterial activities against Candida albicans. With increase of the incorporating percentage of nano-TiO2, the antibacterial effect was enhanced. With the same incorporating percentage, the antibacterial effect of the condition with light was better than that in the dark. When the incorporating percentage was 2.0%, the inhibitory rate was 85.9% with light.4 To study the mechanical function of silicone elastomer, the tensile strength (MPa),the elongation at break (%),the tear strength (kN/m) and the Shore-A hardness were tested. After adding 0.5%,1.0%,1.5%,2.0%(W/W) nano-TiO2,the result showed that with increase of the incorporating percentage of nano-TiO2, the tensile strength ,the elongation at break and the tear strength (kN/m) increased first and then decrease, the Shore-A hardness increased. When the incorporating dose was 1.0% and 1.5%, the tensile strength had significance with control group and when the incorporating percentage was 2.0%, the Shore-A hardness had significance with control group. When the incorporating dose was 1.5%, the mechanical function of silicone elastomer was the best. |
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