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

Abstract

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 (ΔE*) was assessed before and after every 5 min of treatment. The ΔE* and the changes in the fluorescence loss (ΔΔF) 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 ΔF values increased significantly in all groups with the treatment time (p < 0.05). There was a statistically significant correlation between ΔE* and the change in ΔΔF (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.