Application of quantitative light-induced fluorescence technology for tooth bleaching treatment and its assessment: An in vitro study

Objectives: This study aimed to determine the efficacy of a combination of photocatalysts-hydrogen peroxide at a low concentration (3.5%) and titanium dioxide (TiO2)-activated at a wavelength of 405 nm using quantitative light-induced fluorescence (QLF) technology, and to quantify their tooth-bleaching efficacy using fluorescence images obtained from QLF technology. Materials and methods: Forty bovine incisors were extrinsically stained according to Stookey's method, and were randomly divided into four groups (n = 10 per group). Two bleaching solutions were prepared by mixing 3.5% H2O2 with 0.05% of anatase and rutile TiO2 powders. These solutions were applied to the stained teeth using a microbrush and then irradiated for 15 min at either 306 or 405 nm to activate the bleaching agent. The color difference (Delta E*) was assessed before and after every 5 min of treatment. The Delta E* and the changes in the fluorescence loss (Delta Delta F) were obtained from white-light and fluorescence images, respectively. Results: All of the low-H2O2/TiO2 treatments caused significant tooth-bleaching efficacy after irradiation at 306 and 405 nm (p < 0.05). The results did not differ significantly between the two wavelengths (p > 0.05), but the bleaching efficacy was greater with anatase TiO2 at 306 nm and rutile TiO2 at 405 nm. Analysis of the fluorescence images revealed that the Delta F values increased significantly in all groups with the treatment time (p < 0.05). There was a statistically significant correlation between Delta E* - and the change in Delta Delta F (r = 0.822, p < 0.001). Conclusions: Combining low-H2O2/TiO2 with QLF technology at 405 nm has an efficacy of tooth-bleaching as a less harmful and biofriendly method, while the fluorescence images obtained by QLF technology could be used to assess tooth-bleaching.