The Applied Basic Research Of TiO₂Photocatalyst Material On Antibiosis And Cleaning Of Denture Base Material

Part1:Antibacterial properties of P25TiO2against Candida abbicans adhered on denture base materialObjective:To evaluate the antibacterial properties of P25TiO2against Candida abbicans adhered on denture base material in vitro.Methods:50mL bacterial suspension of Candida abbicans1×107CFU/mL was made.10mL was added to a P25TiO2particle mixture (10mg/mL,20mg/mL,25mg/mL) as Group A, B, C.10mL was added to Baolijing mixture (25mg/mL) as Group D and the other lOmL as Group Control (Group E). In the control sample treated with distilled water. All groups were irradiated by UV(5mW/cm2) light at the same time and the bacterial survival rate of each group was calculated for10,20,30,60,90,120min. The culture temperature was maintained at37℃. The antibacterial rates (AR) was calculated with the average value through3repeated trials. After24hours’standing,1mL fresh bacterial suspension of Candida abbicans1×107CFU/mL was added to all groups and the ARs after24hous were calculated.16denture base resin specimens with about30×20×2mm3 were made and cultured in lOmL bacterial suspension of Candida abbicans1×105CFU/mL at37℃for24hours. Then these specimens with Candida abbicans adhered on the surface were put into two groups:Group A was P25TiO2particle mixture of the most effective concentration and Group B was control of distilled water. Group A and B were irradiated by UV(5mW/cm2) light at the same time and the bacterial survival rate on the surface of each group was calculated for10,20,30min. Clinical old dentures were dipped in Aoinn Photocatalyst for2,4,6hour under irradiation, measure the value of L, a, b every2hour with Shadeeye Ncc Ⅱ spectrocolrimeter and find the color difference.Results:In the control group treated with distilled water, the bacterial survived at a high rate even after120min. In the P25TiO2group, the ARs of25mg/mL at10min was over99.9%; The ARs after24hours of25mg/mL at30min was92.18%; The ARs of Candida abbicans adhered on the resin surface at20min was over90%when P25TiO2concentration was25mg/mL. The color differences represented as△E of all the old dentures dipped in25mg/mL TiO2particle mixture in6hours were all above3.7, which means the color difference were significant and could be distinguished by eye.Conclusion:The photocatalytic antibacterial action of the P25TiO2particle mixture (25mg/mL) was high in10min and even after24hours still exist. P25TiO2particle mixture (25mg/mL)can provide favourable effect on removing old dentures’discoloration. Part2:The basic Research of commercial nano TiO2photocatalyst on antibiosis and cleaning of denture base materialObjective:To evaluate the antibacterial properties of commercial nano TiO2photocatalyst against Candida abbicans adhered on denture base material in vitro and the effectiveness of TiO2photocatalyst on removing discoloration of old denture.Methods:Using Aoinn Photocatalyst which is produced by Guangzhou Aoinn Environment Technology Corporation and measure the degradation of methyl blueness by photocatalysis.16denture base resin specimens with about30×20×2mm3were made and cultured in10mL bacterial suspension of Candida abbicans1×105CFU/mL at37℃for24hours. Then these specimens with Candida abbicans adhered on the surface were put into two groups:Group A was Aoinn Photocatalyst and Group B was control of distilled water. Group A and B were irradiated by UV light at the same time and the bacterial survival rate on the surface of each group was calculated for30,60,120,240min. Clinical old dentures were dipped in Aoinn Photocatalyst for2,4,6hour under irradiation, measure the value of L, a, b every2hour with Shadeeye Ncc Ⅱ spectrocolrimeter and find the color difference.Results:The ARs of Aoinn Photocatalyst against Candida abbicans was increased by the increasing of irradiation, and finally reach94.7%. The color difference represented as△E of all old dentures in6hours were above3.7, which means the color difference were significant and could be distinguished by eye.Conclusion:The photocatalytic antibacterial action of Aoinn Photocatalyst was high in60min but not ideal in short time. Aoinn Photocatalyst can provide favourable effect on removing old dentures’discoloration.