Department of Restorative Dentistry, School of Dentistry, Araraquara, São Paulo State University - UNESP, 3rd floor, Humaitá Street, 1680 - Centro, Mail Box: 331, Araraquara, São Paulo 14801-903, Brazil.
Photodiagnosis Photodyn Ther. 2021 Dec;36:102511. doi: 10.1016/j.pdpdt.2021.102511. Epub 2021 Aug 29.
The association of low concentration hydrogen peroxide (HP) and a light source has been widely used to achieve efficient bleaching. We investigated the colorimetric and microstructural changes of bovine enamel bleached with 6% HP associated or not with a hybrid light source system of violet light and laser (LED/laser).
Twenty bovine crowns were used to obtain specimens of 7 × 7 × 2 mm. Then, they were randomized in two groups (n=10): 6% HP and 6% HP + LED/laser. After staining with dark tea solution, three bleaching sessions were performed. Colorimetric evaluation (∆L*, ∆a*, ∆b*, ∆E [CIEDE2000] and WI) after 24 hours of each session and 7 days after the final bleaching session was performed. Enamel Vickers microhardness at baseline, 24 hours and 7 days after the last bleaching session were also evaluated. Two-way repeated measures ANOVA and Bonferroni post-test was used at a significance level of 5%.
6% HP and 6% + HP LED/laser showed satisfactory bleaching results. The group photoactivated showed higher WI values (p<0.05). Differences between groups were observed for ∆E, ∆L* and ∆a* (p<0.05), except for ∆b* (p>0.05). Intra-group differences were also found (p<0.05). Regarding microhardness, no inter or intra-group differences were observed (p>0.05).
The photoactivation with LED/laser enhanced the whitening efficacy of 6% HP compared to the group without photoactivation. Thus, the LED/laser activation appears to be a good option when using low concentration HP-based agents. In addition, both bleaching protocols did not cause changes on enamel microhardness.
低浓度过氧化氢（HP）和光源的联合应用已广泛用于实现高效漂白。我们研究了 6%HP 联合或不联合紫光灯和激光（LED/激光）混合光源系统漂白对牛牙釉质的色度学和微观结构变化。
使用 20 个牛牙冠获得 7×7×2mm 的样本。然后，将其随机分为两组（n=10）：6%HP 和 6%HP+LED/激光。用浓茶溶液染色后，进行三次漂白疗程。每次疗程后 24 小时和最后一次疗程后 7 天进行色度评估（∆L*、∆a*、∆b*、∆E[CIEDE2000]和 WI）。在最后一次漂白疗程后 24 小时和 7 天还评估了牙釉质维氏显微硬度。采用双因素重复测量方差分析和 Bonferroni 事后检验，显著性水平为 5%。
6%HP 和 6%HP+LED/激光均显示出令人满意的漂白效果。光激活组显示出更高的 WI 值（p<0.05）。组间差异观察到∆E、∆L和∆a（p<0.05），但∆b*（p>0.05）除外。组内差异也存在（p<0.05）。关于显微硬度，组间或组内差异均不明显（p>0.05）。
与未光激活组相比，LED/激光的光激活增强了 6%HP 的漂白效果。因此，当使用基于低浓度 HP 的制剂时，LED/激光的激活似乎是一种很好的选择。此外，两种漂白方案均未导致牙釉质显微硬度发生变化。
