Effect of photo-thermal acceleration on in-office bleaching

Abstract

The purpose is to evaluate the effect of photo-thermal acceleration on in-office bleaching efficiency using a bleaching agent without photocatalysts in vitro. Artificially discolored bovine lower incisors were prepared, and the mixed in-office bleaching material contained hydrogen peroxide 23% was applied by following treatment for 10 min: high-(HI group) and low-intensity LED lights (LI group), oven at 38 °C (OV group), and room temperature at 23 °C (RT group). Color was measured before and after bleaching and color difference (∆E*) was calculated. The data were statistically analyzed using a two-way ANOVA and Tukey's post hoc test. The temperature change (∆T) of applied bleaching agent in HI and LI groups was measured using a thermography and was analyzed using a T test. The bleaching procedures were repeated 6 times. Irradiation in the HI group resulted in the highest ΔE, followed by the LI group whose ΔE was significantly lower. Both irradiated modes exhibited higher ΔE compared to non-irradiated OV and RT groups which were not significantly different from each other. The average temperature rise of bleaching agents in HI and LI groups after 10 min irradiation was 15.00 °C and 11.80 °C, respectively. The effect of photo-thermal acceleration was proved for an in-office bleaching agent without photocatalysts in vitro.

Keywords: Hydrogen peroxide; Photo irradiation; Temperature; Tooth bleaching; Tooth color.

Fig. 1

The multiple teeth covered with bleaching material were illuminated for 10 min at 5 mm from the LED

Fig. 2

Mean of ∆L* at each bleaching step in all groups

Fig. 3

Mean of ∆a* at each bleaching step in all groups

Fig. 4

Mean of ∆b* at each bleaching step in all groups

Fig. 5

Mean of color difference values (∆E*) at each bleaching step in all groups. Different uppercase letters represent the statistical differences between groups and different lowercase letters represent the statistical difference between application times (P < 0.05).

Fig. 6

Typical color change in bovine teeth specimens of all groups at each bleaching step

Fig. 7

The average temperature change (∆T) of bleaching agent in HI and LI group after 10 min irradiation. Different lowercase letters represented significant differences between groups (P < 0.05).