Statement of problem

The repairability of computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins might be adversely affected by the high degree of matrix polymerization that occurs during their manufacturing process. However, information on their repairability is lacking.

Purpose

The purpose of this in vitro study was to evaluate the microtensile bond strength of CAD-CAM composite resins subjected to simulated repair procedures by using varying surface treatments and universal adhesives.

Material and methods

Four different CAD-CAM blocks (Brilliant Crios, Lava Ultimate, Shofu Block HC, and Vita Enamic) were thermocycled (5000 times, 5/55 °C) and divided into 4 groups according to the surface treatment: control, 9% hydrofluoric acid etching, aluminum oxide airborne-particle abrasion, and tribochemical silica airborne-particle abrasion. After surface treatments, the surface roughness was measured with a nanoindenter and further examined with scanning electron microscopy. After the application of 3 different universal adhesives (Clearfil Universal Bond, Prime&Bond Universal, and Single Bond Universal), the specimens were subjected to a simulated repair process with composite resin. Bonded specimens were cut into 1 mm² beams, and microtensile bond strength values were determined until failure at a crosshead speed of 0.5 mm/min. The bond strength data were analyzed with 3-way analysis of variance, and surface roughness data were analyzed with 2-way analysis of variance tests. Pairwise analyses were performed with the Tukey test (α=.05).

Results

All surface treatments effectively improved repair microtensile bond strength values compared with the control (P<.05). Aluminum oxide airborne-particle abrasion had similar mean bond strength values compared with tribochemical silica airborne-particle abrasion (P>.05). Among the CAD-CAM blocks treated with hydrofluoric acid etching, Vita Enamic had the highest mean bond strength values. The highest mean microtensile bond strength repair values with the highest cohesive failure rates were found with the silane-containing universal adhesive (Single Bond Universal).

Conclusions

Surface treatment with aluminum oxide airborne-particle abrasion and tribochemical silica airborne-particle abrasion produced successful repair results for aged resin nanoceramics, whereas hydrofluoric acid etching can be used for aged hybrid ceramic repair. Silane-containing universal adhesive reported increased bond strength. Application of universal adhesive after surface treatment is recommended to increase repair strength.

中文翻译：

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不同表面处理和通用粘合剂对CAD-CAM复合树脂修复的影响：一项体外研究。

问题陈述

计算机辅助设计和计算机辅助制造（CAD-CAM）复合树脂的可修复性可能会受到其制造过程中发生的高度基体聚合的不利影响。但是，缺乏有关其可修复性的信息。

目的

这项体外研究的目的是通过使用不同的表面处理和通用粘合剂，对经过模拟修复程序的CAD-CAM复合树脂的微拉伸粘合强度进行评估。

材料与方法

将四种不同的CAD-CAM嵌段（Brilliant Crios，Lava Ultimate，Shofu Block HC和Vita Enamic）进行热循环（5000次，5/55°C），并根据表面处理分为4组：对照，9％氢氟酸蚀刻，氧化铝气载颗粒磨损和摩擦化学二氧化硅气载颗粒磨损。表面处理后，用纳米压头测量表面粗糙度，并进一步用扫描电子显微镜检查。施加3种不同的通用粘合剂（Clearfil通用粘合剂，Prime＆Bond通用粘合剂和Single Bond通用粘合剂）后，将样品用复合树脂进行模拟修复过程。将粘结的样品切成1 mm ²确定横梁和微拉伸粘结强度值，直到以0.5 mm / min的十字头速度破坏为止。结合强度数据通过三项方差分析进行分析，而表面粗糙度数据则通过两项方差分析进行分析。用Tukey检验（α= .05）进行成对分析。

结果

与对照相比，所有表面处理均有效改善了修复微拉伸结合强度值（P <.05）。与摩擦化学二氧化硅空气颗粒的磨损相比，氧化铝空气颗粒的磨损具有相似的平均粘结强度值（P > .05）。在用氢氟酸蚀刻处理的CAD-CAM块中，Vita Enamic的平均粘结强度值最高。用含硅烷的通用胶粘剂（单键通用胶粘剂）发现具有最高内聚破坏率的最高平均微拉伸胶粘强度修复值。

结论

氧化铝空气颗粒磨损和摩擦化学二氧化硅空气颗粒磨损的表面处理对老化的树脂纳米陶瓷产生了成功的修复结果，而氢氟酸蚀刻可用于老化的混合陶瓷修复。含硅烷的通用胶粘剂报告了增加的粘结强度。建议在表面处理后使用通用粘合剂，以提高修复强度。