Hydrogen peroxide penetration into the pulp chamber during conventional in-office bleaching and diode laser-assisted bleaching with three different wavelengths.

Background and aims: Penetration of hydrogen peroxide into the pulp chamber and subsequent tooth hypersensitivity is a common concern in dental bleaching. The aim of this study was to assess the penetration of hydrogen peroxide (H₂O₂) into the pulp chamber in diode-laser activated bleaching with different laser wavelengths.

Materials and methods: Fifty extracted human maxillary anterior teeth were collected and divided into five groups(n = 10). Group 1: conventional in-office bleaching using Opalescence Boost gel. Group 2: Bleaching with Biolase Laser White 20 gel activated by 980 nm diode laser. Group 3: Bleaching with Biolase Laser White 20 gel activated by 810 nm diode laser. Group 4: Bleaching with Biolase Laser White 20 gel activated by 940 nm diode laser. Group 5: No bleaching control group.After bleaching, the solution into the pulp chamber was collected and analyzed using a spectrophotometer. The recorded data were compared with a standard sample and the results were analyzed and compared using one-way ANOVA and Tukey's HSD tests.

Results: In all bleached groups, H₂O₂ had infiltrated into the pulp chamber. The highest level of penetration was noted in group 2 (2.32 ± 0.25 µg), while the lowest level was noted in group 3 (1.85 ± 0.33 µg). The difference in this regard was significant between groups 2 and 3 (P = 0.024), but the differences between other groups were not statistically significant (P ≥ 0.42).

Conclusion: Considering the results of this study, it can be stated that hydroge peroxide penetration in to pulp chamber in diode laser activation of bleaching agent according to manufactures instruction is not higher than in-office bleaching. The wavelength of diode laser had significant effect on penetration of hydrogen peroxide into pulp chamber.