Borges A B, Dos Santos K C, da Silva D F, Bottesini V C, Torres Crg, Mailart M C
Alessandra Bühler Borges, DDS, MSc, PhD, full professor, Department of Restorative Dentistry, Institute of Science and Technology, São Paulo State University, São José dos Campos, SP, Brazil.
Karine Carvalho dos Santos, DDS, undergraduate student, Department of Restorative Dentistry, Institute of Science and Technology, São Paulo State University, São José dos Campos, SP, Brazil.
Oper Dent. 2025 Jul 14. doi: 10.2341/24-142-L.
Various in vitro approaches have been used to evaluate whitening efficacy, utilizing both stained and non-stained tooth substrates, which may influence the outcomes. This study aimed to assess the effect of previous in vitro staining on whitening efficacy and the enamel surface using hydrogen peroxide (HP) gels with different concentrations.
Bovine enamel/dentin specimens (n=16) were randomly allocated into groups according to the HP concentration [20% (HP20), 30% (HP30), 40% (HP40), and deionized water (negative control)]; and substrate condition (non-stained or stained). Tooth color was measured using a spectrophotometer, and the color difference (ΔE00) and whiteness index (WID and ΔWID) were calculated. Knoop surface microhardness (SMH) and roughness (Ra) of enamel were assessed at different times. Data from both non-stained and stained substrates were analyzed using ANOVA and Tukey post hoc tests (α<0.05).
Significant differences were observed in ΔE00 for different HP concentrations and substrate conditions (p<0.001). Greater tooth color change was found for HP40, followed by HP30 and HP20. Stained groups exhibited higher ΔE00 values than non-stained ones, except for HP20. Higher values of ΔWID were observed in stained/bleached groups. The staining process reduced SMH and increased Ra.
The bleaching patterns were similar for both non-stained and stained substrates, with higher concentrations of HP bleaching gels resulting in greater tooth color difference. Previous staining increased the variation in whiteness values (ΔWID) following bleaching, but specimens maintained a lower whiteness index after bleaching compared to the non-stained substrate. Staining induced alterations on the enamel surface. These factors indicate that pre-staining of specimens is not essential to evaluate the whitening efficacy of bleaching gels.
已采用多种体外方法来评估美白效果，使用了染色和未染色的牙齿基质，这可能会影响结果。本研究旨在评估先前的体外染色对使用不同浓度过氧化氢（HP）凝胶的美白效果和牙釉质表面的影响。
将牛牙釉质/牙本质标本（n = 16）根据HP浓度[20%（HP20）、30%（HP30）、40%（HP40）和去离子水（阴性对照）]以及基质状况（未染色或染色）随机分组。使用分光光度计测量牙齿颜色，并计算色差（ΔE00）和白度指数（WID和ΔWID）。在不同时间评估牙釉质的努氏表面显微硬度（SMH）和粗糙度（Ra）。使用方差分析和Tukey事后检验（α<0.05）分析未染色和染色基质的数据。
在不同HP浓度和基质状况下，ΔE00存在显著差异（p<0.001）。HP40组的牙齿颜色变化更大，其次是HP30组和HP20组。除HP20组外，染色组的ΔE00值高于未染色组。在染色/漂白组中观察到更高的ΔWID值。染色过程降低了SMH并增加了Ra。
未染色和染色基质的漂白模式相似，HP漂白凝胶浓度越高，牙齿颜色差异越大。先前的染色增加了漂白后白度值（ΔWID）的变化，但与未染色基质相比，标本在漂白后保持较低的白度指数。染色导致牙釉质表面发生改变。这些因素表明，标本预染色对于评估漂白凝胶的美白效果并非必不可少。
