Statement of problem

Veneering composite resins (VCRs) are often used to veneer frameworks, but knowledge of mechanical, surface, and discoloring properties is scarce.

Purpose

The purpose of this in vitro study was to evaluate the impact of thermocycling on flexural strength (FS) and the influence of different staining media on the discoloration (ΔE) and surface free energy (SFE) of VCRs.

Material and methods

The following VCRs were tested: Ceramage, dialog Vario, Gradia Plus, in:joy, Signum composite, and SR Nexco. FS was tested with enamel and dentin pastes (except SR Nexco: only enamel paste), whereas ΔE and SFE were analyzed for enamel pastes. ΔE was determined by using a spectrophotometer, and SFE was evaluated with contact angle measurements. For FS, rod-shaped specimens (N=660, n=10/subgroup; 25×2×2 mm) were fabricated, thermocycled for 220, 1500, 10 000, 20 000, and 40 000 cycles (5 °C/55 °C). and tested immediately after fabrication (initial) and after aging. For ΔE and SFE, disc-shaped specimens (N=300, n=10/subgroup; 15x15x1.4 mm) were fabricated and stored for 14 days in coffee, red wine, carrot juice, beetroot juice, or curry solution. ΔE and SFE were measured initially after polishing, after discoloration, and after repolishing. Data were analyzed using univariate analysis, 1-way ANOVA followed by the Scheffé post hoc test, Kolmogorov-Smirnov test, Kruskal-Wallis test, Mann-Whitney U test, and Wilcoxon test (α=.05).

Results

Ceramage had the highest FS, followed by dialog Vario and SR Nexco. Gradia Plus, and in:joy had the lowest FS, followed by Signum composite. FS was reduced by increasing of thermocycles. The highest ΔE was measured for curry and the lowest for carrot juice and red wine, followed by beetroot juice and coffee. The highest ΔE between the initial polished specimens and repolished specimens were observed for Ceramage. The remaining VCRs showed differences in ΔE between 0.95 (Signum composite) and 1.30 (SR Nexco). The SFE of the VCRs was similar. After storage in discoloring media, all VCRs had higher SFE than directly after polishing (initial). Repolishing decreased the SFE values compared with those of specimens measured after storage.

Conclusions

FS, ΔE, and SFE differed between the VCRs tested. Discoloration of the VCRs depended on the food and beverage and could be corrected to a clinically acceptable range by repolishing.

中文翻译：

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热循环对贴面复合树脂在各种染色介质中储存后的力学性能和变色的影响

问题陈述

饰面复合树脂（VCR）通常用于单板框架，但缺乏机械，表面和变色特性的知识。

目的

这项体外研究的目的是评估热循环对弯曲强度 (FS) 的影响以及不同染色介质对 VCR 的变色 (ΔE) 和表面自由能 (SFE) 的影响。

材料与方法

测试了以下 VCR：Ceramage、dialog Vario、Gradia Plus、in:joy、Signum Composite 和 SR Nexco。FS 用牙釉质和牙本质糊剂（SR Nexco 除外：仅牙釉质糊剂）进行测试，而对牙釉质糊剂分析 ΔE 和 SFE。使用分光光度计确定ΔE，并通过接触角测量评估SFE。对于 FS，制造棒状试样（N=660，n=10/亚组；25×2×2 mm），热循环 220、1500、10 000、20 000 和 40 000 次循环（5 °C/55 °C）。并在制造（初始）和老化后立即进行测试。对于 ΔE 和 SFE，制作了圆盘状标本（N=300，n=10/亚组；15x15x1.4 mm）并在咖啡、红酒、胡萝卜汁、甜菜根汁或咖喱溶液中储存 14 天。ΔE 和 SFE 在抛光后、变色后和重新抛光后进行初始测量。

结果

Ceramage 的 FS 最高，其次是 dialog Vario 和 SR Nexco。Gradia Plus 和 in:joy 的 FS 最低，其次是 Signum 复合材料。FS 随热循环的增加而降低。咖喱的 ΔE 最高，胡萝卜汁和红酒的 ΔE 最低，其次是甜菜根汁和咖啡。观察到最初的抛光试样和再抛光的试样之间的最高ΔE为Ceramage。其余 VCR 的 ΔE 差异在 0.95（Signum 复合材料）和 1.30（SR Nexco）之间。VCR 的 SFE 是相似的。在变色介质中储存后，所有 VCR 的 SFE 都高于抛光后（初始）。与储存后测量的样品相比，重新抛光降低了 SFE 值。

结论

FS、ΔE 和 SFE 在测试的 VCR 之间不同。VCR 的变色取决于食物和饮料，可以通过重新抛光将其校正到临床可接受的范围。