The effect of hydrofluoric acid and resin cement formulation on the bond strength to lithium disilicate ceramic

Abstract To investigate how the hydrofluoric acid (HF) concentrations applied to a lithium disilicate glass-ceramic (EMX) affects the surface morphology and microtensile bond strength (μTBS) of ceramics to dentin, using light-cured resin cements with or without UDMA. Sixty-three EMX square ceramic blocks were etched for 20 seconds using different HF concentrations (1%, 5% and 10%) and luted to dentin using two types of resin cement combinations: BisGMA/TEGDMA and BisGMA/TEGDMA/UDMA (n = 10). Each bonded EMX-dentin block was sectioned to obtain 1 mm2 sticks for μTBS evaluation. Half of the sticks were tested after 24 hours and the other half was assessed after 6 months of water storage. Data were statistically assessed using split-plot three-way ANOVA and multiple comparisons were performed using the Tukey's post hoc test (α = 0.05). One EMX sample from each HF concentration was analyzed using field-emission scanning electron microscope (FE-SEM) to characterize the etching pattern. According to the FE-SEM images, increasing the concentration of HF from 1 to 5 and then to 10% led to increased removal of glassy matrix and greater exposure of lithium disilicate crystals. The 10% HF concentration yielded higher μTBS when compared to 1% for BisGMA/TEGDMA formulation (p < 0.05); whereas HF 1% and 5% showed similar μTBS values when compared to 10% HF for BisGMA/TEGDMA/UDMA resin matrix (p > 0.05) at both storage times. Water aging decreased the μTBS values (p < 0.05), except when 10% HF was associated with BisGMA/TEGDMA resin cement. Resin cement formulation and hydrofluoric acid concentrations can interfere with the immediate and long-term glass-ceramic bond strength to dentin.

摘要：为探究氢氟酸（HF）作用于二硅酸锂玻璃陶瓷（EMX）时，其浓度对陶瓷表面形貌，以及陶瓷与牙本质分别使用含与不含氨基甲酸酯二甲基丙烯酸酯（UDMA）的光固化树脂水门汀粘结后的微拉伸粘结强度（μTBS）的影响。本研究共制备63块EMX方形陶瓷块，采用1%、5%、10%三种不同浓度的HF溶液蚀刻20秒，随后使用两种树脂水门汀组合（BisGMA/TEGDMA与BisGMA/TEGDMA/UDMA）将陶瓷粘结至牙本质样本，每组样本量n=10。将每一组粘结完成的EMX-牙本质块切割为1 mm²的试条以开展μTBS测试：其中一半试条于粘结后24小时进行强度检测，另一半则经6个月水储存后进行评估。采用裂区设计三因素方差分析对实验数据进行统计学评估，并通过Tukey事后检验进行多重比较（检验水准α=0.05）。从每一种HF浓度处理的EMX样本中各选取1份，使用场发射扫描电子显微镜（FE-SEM）表征其蚀刻后的表面形貌。FE-SEM成像结果显示，随着HF浓度从1%提升至5%再至10%，陶瓷表面玻璃基质的去除程度逐渐升高，二硅酸锂晶体的暴露量也同步增加。对于BisGMA/TEGDMA树脂水门汀组，10% HF浓度处理的样本μTBS显著高于1% HF浓度组（p<0.05）；而对于BisGMA/TEGDMA/UDMA树脂水门汀组，在两种储存时间下，1%、5% HF浓度组与10% HF浓度组的μTBS值均无显著差异（p>0.05）。水老化处理可显著降低样本的μTBS值（p<0.05），但当10% HF与BisGMA/TEGDMA树脂水门汀联用时除外。研究结果表明，树脂水门汀配方与氢氟酸浓度均可影响玻璃陶瓷与牙本质的即刻及长期粘结强度。