IADR Abstract Archives
Antibacterial Activity of Gypsum Model Coated with Photocatalyst
Objectives: Gypsum models contaminated with pathogenic microbes can cause some infection diseases if they are used without appropriate preventions. In this study, applicability of photocatalysts exhibiting catalytic activities in UV or visible light region to an antibacterial coating material was examined.
Methods: Disk shaped specimens (2 mm diameter, 7 mm thickness) were prepared by pouring the mixture of dental stone powder and water into each alginate impression. The specimens were treated by coating with anatase TiO2 or WO3 dispersed in a commercial dental stone hardener (SH). After dropping of 0.3 ml of the bacteria solution (Staphylococcus aureus, 5.0×107 /ml), the specimens coated with TiO2/SH were irradiated with UV and those coated with WO3/SH were irradiated with visible light for 0 or 24 hr at 25±2 °C. The numbers of the surviving bacteria attached to specimens were examined by agar pour plate method after wash method for collecting the bacteria. In the similar way, the surviving bacteria numbers in the specimens without coating and those coated with only SH were also examined.
Results: The surviving bacteria remained in the specimens without coating were decreased from 2×107 to 2×106 by 24-hr UV irradiation. In the specimens coated with SH, the level of 105 surviving bacteria still remained. On the other hand, no surviving bacteria were detected in the specimens coated with TiO2/SH after the irradiation (p<0.05). After 24-hr visible light irradiation, the level of 107 surviving bacteria remained in the specimens without coating and those coated with SH. The coating treatment with WO3/SH reduced in the surviving bacteria numbers; however, the level of 106 surviving bacteria still remained.
Conclusions: It suggested that anatase TiO2 dispersed in the commercial dental stone hardener was applicable to an antibacterial coating material for gypsum model.
Methods: Disk shaped specimens (2 mm diameter, 7 mm thickness) were prepared by pouring the mixture of dental stone powder and water into each alginate impression. The specimens were treated by coating with anatase TiO2 or WO3 dispersed in a commercial dental stone hardener (SH). After dropping of 0.3 ml of the bacteria solution (Staphylococcus aureus, 5.0×107 /ml), the specimens coated with TiO2/SH were irradiated with UV and those coated with WO3/SH were irradiated with visible light for 0 or 24 hr at 25±2 °C. The numbers of the surviving bacteria attached to specimens were examined by agar pour plate method after wash method for collecting the bacteria. In the similar way, the surviving bacteria numbers in the specimens without coating and those coated with only SH were also examined.
Results: The surviving bacteria remained in the specimens without coating were decreased from 2×107 to 2×106 by 24-hr UV irradiation. In the specimens coated with SH, the level of 105 surviving bacteria still remained. On the other hand, no surviving bacteria were detected in the specimens coated with TiO2/SH after the irradiation (p<0.05). After 24-hr visible light irradiation, the level of 107 surviving bacteria remained in the specimens without coating and those coated with SH. The coating treatment with WO3/SH reduced in the surviving bacteria numbers; however, the level of 106 surviving bacteria still remained.
Conclusions: It suggested that anatase TiO2 dispersed in the commercial dental stone hardener was applicable to an antibacterial coating material for gypsum model.