Effect of light units on tooth bleaching with visible-light activating titanium dioxide photocatalyst

Abstract

This study evaluated the influence of different light sources on the efficiency of an office bleaching agent containing visible-light activating titanium dioxide photocatalyst (VL-TiO2) using an artificial discoloration tooth model. Extracted bovine teeth were stained by black tea. The CIE L*a*b* values were measured before and after nine consecutive treatments by the VL-TiO2-containing bleaching agent (TiON in Office, GC, Tokyo, Japan). A halogen light unit (CB; CoBee, GC) or an LED unit (G-light, GC) with two modes (blue and violet: GL-BV, blue: GL-B) were used to activate the bleaching agent in three groups (n=8). Brightness (ΔL) and color difference (ΔE) increased as bleaching repeated in all groups. Two-way ANOVA showed that both number of treatments and light sources significantly affected ΔE (p<0.05). GL-BV showed better bleaching effect than GL-B. In measurement of irradiation spectra, CB showed a wide spectrum (380-530 nm), GL-B had a sharp peak at 470 nm and GL-BV showed an additional peak at 405 nm. It was concluded that the light source influenced the efficiency of the tooth bleaching with VL-TiO2.