Objective

Low pH neutralization and subsequent remnant hydrophilicity can lead to hygroscopic expansion of self-adhesive resin cements (SARCs) after water storage. The aim of this in vitro study was to investigate the effects of hygroscopic expansion of SARCs, used as luting and partial core build-up material, on integrity and cement gap thickness increase of all-ceramic CAD/CAM crowns.

Methods

Human third molars (n = 48) were prepared and anatomical all-ceramic CAD/CAM crowns were manufactured (VITABLOCS Mark II, VITA Zahnfabrik). Crowns internal surfaces were HF etched and silanized. The prepared teeth with their respective crowns were divided into 6 groups (n = 8). In groups 1, 3 and 5 the coronal dentin was removed to simulate a partial core build-up. Groups 1 and 2 were luted with iCEM (Heraeus Kulzer), 3 and 4 with RelyX Unicem 2 Automix (3M), 5 and 6 with Variolink Esthetic DC (Ivoclar Vivadent). All specimens were dual cured and stored in distilled water at 37 °C. Crown integrity was controlled at baseline and in regular intervals until 180 days. Cement gap thickness was measured using an optical 3D scanner (ATOS Triple scan, GOM) at baseline and after 180 days. Crown integrity was statistically analysed using Kaplan–Meier survival analysis and cement gap thickness increase using two-way ANOVA (α = 0.05).

Results

After 180 days storage, crack formation was observed in all specimens of group 1 (mean survival time of 85.5 days), in one specimen of group 2 and in two specimens of group 4. Two-way ANOVA analysis revealed a statistically significant interaction between material type and build-up on cement gap size increase for iCEM.

Significance

Within the limits of this study, the application of SARCs with low pH neutralization as partial build-up material under CAD/CAM crowns is not recommended for clinical use.

中文翻译：

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自粘树脂胶粘剂的吸湿性和全瓷冠的完整性

客观的

低pH中和和随后的残留亲水性可能导致自粘树脂水泥（SARC）吸水后的吸湿膨胀。这项体外研究的目的是研究SARCs的吸湿性扩展（用作浸胶和部分堆芯材料）对全陶瓷CAD / CAM牙冠的完整性和水泥间隙厚度增加的影响。

方法

准备了人类的第三磨牙（n = 48），并制造了解剖学上全陶瓷的CAD / CAM牙冠（VITABLOCS Mark II，VITA Zahnfabrik）。冠的内表面经过HF蚀刻和硅烷化处理。准备好的带有各自牙冠的牙齿分为6组（n = 8）。在第1、3和5组中，将冠状牙本质去除以模拟部分核心堆积。第1组和第2组使用iCEM（Heraeus Kulzer），第3组和第4组使用RelyX Unicem 2 Automix（3M），第5组和第6组使用Variolink Esthetic DC（Ivoclar Vivadent）。所有样品均经过双重固化，并保存在37°C的蒸馏水中。在基线和180天之前定期控制牙冠的完整性。在基线和180天后，使用光学3D扫描仪（ATOS Triple scan，GOM）测量水泥缝隙厚度。α  = 0.05）。

结果

储存180天后，在第1组的所有标本（平均生存时间为85.5天），第2组的一个标本和第4组的两个标本中均观察到裂纹形成。双向方差分析表明材料之间存在统计学上的显着相互作用iCEM的水泥类型和水泥间隙尺寸的增加。

意义

在本研究的范围内，不建议将具有低pH中和值的SARC作为CAD / CAM冠下的部分堆积材料的临床应用。