Application of Photocatalytic Thin Titanium Dioxide Films for Antibacterial and Stain-proof Dental Materials

本文研究了光活化复合树脂包覆含银离子的二氧化钛薄膜对变形链球菌和白色念珠菌的抑菌活性。该树脂复合材料由粉末（硅化SiO2填料）和液体（49.5 wt%三乙二醇二甲基丙烯酸酯（TEGDMA）、49.5 wt%聚氨酯二甲基丙烯酸酯（UDMA）、0.5 wt%樟脑醌和0.5 wt% 2-（二甲氨基）甲基丙烯酸乙酯）组成。将粉末和液体以3/1的重量比混合，在光固化单元中对每侧的试样圆盘进行聚合，时间为90s。涂层处理在胶体溶液中进行，胶体溶液分散1.5 wt%的含银离子的二氧化钛细颗粒（平均5nm）。部分试样在0.4 MPa, 80℃，20wt%的胶体溶液中浸泡30min。对照组采用非涂层tegdma - udma基树脂复合材料。在37℃的水中浸泡1天或3个月。考察了其表面性能、抑菌活性及对钛、银离子的释放。通过原子力显微镜观察，在树脂复合材料表面形成了厚度约为0.1 μm的涂层。包被的样品在水中浸泡1天和3个月后对变形链球菌和白色念珠菌的生长有抑制作用，而未包被的样品则没有。在两个实验期间，包覆试样在水中均没有钛离子的释放。保存3个月的包膜标本水中仅检测到少量银离子（15.6±1.4 ng/cm^2）。这些结果表明，光活化树脂复合包覆含银离子的二氧化钛膜的活性可归因于银离子的释放和表面银的催化作用。因此，这种涂层处理似乎适合临床使用。

The purpose of the present study was to investigate the antibacterial activity of thin silver-ion-containing titanium dioxide films coated on light-activated resin composite against Streptococcus mutans and Candida albicans. The resin composite was composed of powder (silanized SiO2 filler) and liquid (49.5 wt% triethylene glycol dimethacrylate (TEGDMA), 49.5 wt% urethane dimethacrylate (UDMA), 0.5 wt% camphorquinone, and 0.5 wt% 2-(dimethylamino) ethyl methacrylate). The powder and liquid were mixed at a 3/1 ratio by weight and the specimen disks were polymerized on each side in a photo-curing unit for 90 s. Coating treatment was performed in a colloidal solution dispersing 1.5 wt% fine particles (average 5 nm) of silver-ion-containing titanium dioxide. Some specimens were dipped in 20wt% colloidal solution at 0.4 MPa, 80℃ for 30 min. For controls, noncoated TEGDMA-UDMA-based resin composite was used. The specimens were immersed in water at 37℃ for 1 day or 3 months. The surface properties, antibacterial activities, and release of titanium and silver ions were examined. A coating film with an approximately 0.1 μm thickness was confirmed on the resin composite surface by atomic force microscopy. The coated specimens inhibited the growth of S.mutans and C.albicans after immersion in water for 1 day and 3 months, whereas the noncoated specimens did not. There was no release of titanium ions from the coated specimens after immersion in water during either experimental period. Only small amounts of silver ions (15.6±1.4 ng/cm^2) were detected in the water from the coated specimens stored for 3 months. These results suggest that the activity of light-activated resin composite coated silver-ion-containing titanium dioxide films can be attributed to both silver ions released and the catalytic action of silver at the surface. Thus, this coating treatment appears to be suitable for clinical use.