Seto Kevin B, McLaren Edward A, Caputo Angelo A, White Shane N
Dental Student, UCLA School of Dentistry, Los Angeles, CA.
Clinical Associate Professor, UCLA School of Dentistry, Los Angeles, CA.
J Prosthodont. 2013 Oct;22(7):523-528. doi: 10.1111/jopr.12053. Epub 2013 May 31.
Resinous cements are widely used for luting zirconia restorations. Adhesive failures have occurred at the cement/zirconia interface, rather than at the cement/dentin interface, suggesting that the cement/zirconia bond may lack durability; however, few comprehensive, comparative evaluations of fatigue effects have been reported. The rate of fatigue-induced loss of bond strength may be a more important predictor of long-term success than a single snapshot of bond strength after an arbitrary number of thermocycles. Previous studies have failed to identify trends by investigating bond strengths at several different numbers of cycles. This may result in invalid conclusions about which cements have superior bond strengths. The purpose of this study was to investigate the effects of artificial aging by thermocycling and resinous cement type on bond strengths to zirconia.
The effect of the number of thermocycles (0, 1, 10, 100, 1000, and 10,000) on the bond strengths of five resinous cements, two of which were used with and without a primer, and an oxygen-inhibiting gel, was studied. Specimens were randomly assigned to thermocycle number/cement-type test groups. Because zirconia has a very low thermal diffusivity, exceptionally long thermocycle dwell times were used. Cylinders of zirconia were bonded end-to-end. One end of each bonded specimen was insulated, specimens were thermocycled and tested in shear, and bond strengths were calculated and analyzed.
Two-way ANOVA revealed that the effects of cement type, the number of thermocycles, and their interaction all significantly affected bond strength (p < 0.0001). By 10,000 cycles, most cements had lost at least half of their initial bond strengths, and two cements effectively recorded zero bond strengths. Failure modes were cement specific, but adhesive modes predominated. Fatigue resistance of two cements was greatly improved by use of a primer and an oxygen-inhibiting gel, as recommended by their respective manufacturers.
Both the type of resin cement and the number of thermocycles influenced bond strength. Fatigue through thermocycling affected different cement types in different ways. Some materials displayed more rapid loss of bond strength than others. Cements differed in their failure modes.
树脂水门汀广泛用于粘结氧化锆修复体。粘结失败多发生在水门汀/氧化锆界面，而非水门汀/牙本质界面，这表明水门汀/氧化锆之间的粘结可能缺乏耐久性；然而，关于疲劳效应的全面、比较性评估报道较少。与任意数量热循环后粘结强度的单一快照相比，疲劳导致的粘结强度损失率可能是长期成功的更重要预测指标。以往研究通过调查不同循环次数下的粘结强度未能确定趋势。这可能导致关于哪种水门汀具有更高粘结强度的结论无效。本研究的目的是调查热循环人工老化和树脂水门汀类型对氧化锆粘结强度的影响。
研究了热循环次数（0、1、10、100、1000和10000）对五种树脂水门汀粘结强度的影响，其中两种水门汀使用时添加或不添加底漆以及氧抑制凝胶。样本被随机分配到热循环次数/水门汀类型测试组。由于氧化锆的热扩散率非常低，因此使用了极长的热循环停留时间。将氧化锆圆柱体端对端粘结。每个粘结样本的一端进行绝缘处理，样本进行热循环并进行剪切测试，计算并分析粘结强度。
双向方差分析显示，水门汀类型、热循环次数及其相互作用均对粘结强度有显著影响（p < 0.0001）。到10000次循环时，大多数水门汀至少损失了其初始粘结强度的一半，两种水门汀的有效粘结强度记录为零。失败模式因水门汀而异，但粘结模式占主导。按照各自制造商的建议使用底漆和氧抑制凝胶，两种水门汀的抗疲劳性得到了极大提高。
树脂水门汀类型和热循环次数均影响粘结强度。热循环引起的疲劳以不同方式影响不同类型的水门汀。一些材料的粘结强度损失比其他材料更快。水门汀的失败模式各不相同。
