New approach for dental bleaching by laser

Laser-matter interaction plays an important role in dental bleaching.

This in vitro study evaluated whether a charcoal-containing hydrogen peroxide paste irradiated with different powers of an 810 nm diode laser for a short application time could enhance bleaching efficacy while maintaining intrapulpal temperature below 5.5 °C and enamel surface integrity compared with a standard commercial in-office hydrogen peroxide system.

A total of 112 extracted human premolars were divided into two groups. Fifty-six samples were artificially stained for color measurement, and 56 non-stained samples were used for intrapulpal temperature, surface roughness, and representative scanning electron microscopy assessment. Each group was divided into seven subgroups: commercial in-office hydrogen peroxide system, experimental paste without laser irradiation, and experimental paste irradiated with an 810 nm diode laser at 1, 1.5, 2, 2.5, or 3 W for 30 s. Color change was calculated using the CIE Lab* system. Color change and surface roughness change were analyzed using one-way ANOVA followed by Tukey's HSD post hoc test, whereas intrapulpal temperature change was analyzed using the Kruskal-Wallis test followed by Dunn-Bonferroni post hoc comparisons.

The experimental paste without laser produced the lowest color change (Tukey's HSD, p<0.05 vs. all other subgroups), whereas laser-irradiated subgroups at 1, 1.5, and 2 W produced ΔE values comparable to the commercial system (Tukey's HSD, p>0.05) and laser irradiated subgroups at 2.5 and 3 W produced more color change than the commercial system (Tukey's HSD, p<0.05) despite the shorter application time. Mean ΔE increased from 9.01 ± 2.32 at 1 W to 14.91 ± 2.72 at 3 W. Mean Intrapulpal temperature change increased with laser power (Kruskal-Wallis, p<0.05); 1, 1.5, 2 and 2.5 W remained below the 5.5 °C safety threshold, while 3 W exceeded it. Surface roughness changes were greater at higher powers, with the 3 W subgroup showing a greater change than the commercial system subgroup (Tukey's HSD, p<0.05).

The 810 nm diode laser enhanced bleaching efficacy of the experimental paste. New laser protocol produces color change comparable or more of commercial in-office bleaching system within short application time with or without additional side effects depending on laser power.