The effect of a bleaching agent on the pigment removal and the bond strength of bulk-fill resin composites: an in vitro study

Abstract Introduction In order to simplify the technique, reduce the time required for direct adhesive restorations, bulk-fill resin composites have been developed be applied in bulk placement up to 4 mm increments. Objective Evaluating the color change (ΔE) and the microtensile bond strength (μTBS) of bulk fill resin composites (BFRC) to dentin after the immersion in regular beverages and the application of bleaching systems. Method Forty-five human molar teeth were randomly distributed in three groups according to the filling material (n=15): Filtek Bulk Fill, Tetric N Ceram Bulk Fill and Filtek Z100. The restored teeth were immersed in coffee, wine and distilled water (n=5) for 72 hours. The color parameters were measured using a spectrophotometer, having as basis the CIE L*a*b*, before and after tooth staining and application of bleaching processes. Subsequently, the teeth were sectioned to obtain the specimens for the microtensile testing. The ΔE values were analyzed applying the Kruskal-Wallis and the Wilcoxon tests, and the μTBS values were analyzed applying the ANOVA and the Bonferroni tests (p<0.05). Result There were no significant differences in the ∆E values when comparing the BFRCs to the conventional resin composite (CRC) in most of the experimental groups. The ∆E values did not present significant differences before and after the application of bleaching processes for all the tested resin composites. The BFRCs presented higher μTBS values than the CRC after exposure to distilled water, wine and bleaching agent. Conclusion The studied BFRCs presented similar color stability to the CRC. The BFRCs presented higher bond strength to the dentin than the CTC in most of the evaluated conditions. The bleaching agent was not effective in whitening the stained restored teeth.

摘要 为简化操作流程、缩短直接粘接修复所需时长，大块充填树脂复合材料（bulk-fill resin composites）应运而生，其可采用一次性充填方式，单次充填厚度可达4mm。目的 评估大块充填树脂复合材料（bulk-fill resin composites, BFRC）经常规饮品浸泡及漂白系统处理后，与牙本质间的颜色变化值（ΔE）及微拉伸粘结强度（microtensile bond strength, μTBS）。方法 选取45颗人磨牙，按充填材料随机分为3组（每组n=15）：Filtek Bulk Fill、Tetric N Ceram Bulk Fill及Filtek Z100。将修复后的牙齿分别置于咖啡、红酒及蒸馏水中浸泡72小时（每组5颗）。基于CIE L*a*b*色彩空间，采用分光光度计在牙齿染色及漂白处理前后分别测量色彩参数。随后将牙齿切片以制备微拉伸测试试样。采用克鲁斯卡尔-沃利斯（Kruskal-Wallis）检验与威尔科克森（Wilcoxon）检验分析ΔE值，采用方差分析（ANOVA）及邦费罗尼（Bonferroni）检验分析μTBS值（检验水准p<0.05）。结果 在多数实验组中，大块充填树脂复合材料与传统树脂复合材料（conventional resin composite, CRC）的ΔE值无显著统计学差异。所有受试树脂复合材料在漂白处理前后的ΔE值均无显著差异。经蒸馏水、红酒浸泡及漂白剂处理后，大块充填树脂复合材料的μTBS值高于传统树脂复合材料。结论 本研究涉及的大块充填树脂复合材料的颜色稳定性与传统树脂复合材料相近。在多数评估条件下，大块充填树脂复合材料与牙本质的粘结强度高于传统树脂复合材料。漂白剂对染色后的修复牙齿并无美白效果。