Tam L E, Yim D
Department of Restorative Dentistry, University of Toronto, Canada.
J Dent. 1997 May-Jul;25(3-4):339-46. doi: 10.1016/s0300-5712(96)00031-0.
The fracture toughness test was recently introduced as a clinically relevant method for assessing the fracture resistance of the dentine-composite interface. The objective of this study was to evaluate the effect of dentine depth on the interfacial fracture toughness test of several dentine-composite interfaces using some new proprietary dentine bonding agents.
Miniature short rod fracture toughness specimens containing a chevron-shaped dentine-composite-bonded interface were prepared for each group (n = 12). Six different dentine bonding agents and two dentine depths were the variables assessed at the dentine-composite interfaces. After 24 h at 37 degrees C in water, the specimens were tested by loading at 0.5 mm/min in the Instron Universal Testing Machine. The interfacial KIC results were analysed by ANOVA, unpaired Student's t-tests and Fisher's LSD test (P < 0.05).
The interfacial KIC results in MN.m-3/2 (S.D.) on superficial and deep dentine, respectively, were: All-Bond 2, 0.80 (0.21), 0.44 (0.13); Bond-lt, 0.75 (0.20), 0.38 (0.19); Prime and Bond, 0.56 (0.11), 0.28 (0.10); Scotchbond Multi-Purpose, 0.45 (0.23), 0.26 (0.15); One-Step and OptiBond, insufficient results due to premature specimen failures.
The results from this study should contribute to the development of the fracture toughness test as a method for assessing the integrity of the dentine-composite interface. The interfacial fracture toughness test determined significant differences among the different dentine bonding agents and between the superficial and deep dentine substrates. The dentine bonding agents showed significantly reduced interfacial fracture toughness results when bonding to deep versus superficial dentine.
断裂韧性测试最近被引入作为评估牙本质 - 复合材料界面抗断裂性的一种临床相关方法。本研究的目的是使用一些新型专利牙本质粘结剂，评估牙本质深度对几种牙本质 - 复合材料界面的界面断裂韧性测试的影响。
为每组制备了包含人字形牙本质 - 复合材料粘结界面的微型短棒断裂韧性试样（n = 12）。六种不同的牙本质粘结剂和两种牙本质深度是在牙本质 - 复合材料界面评估的变量。在37℃水中放置24小时后，在英斯特朗万能材料试验机上以0.5mm/分钟的加载速度对试样进行测试。通过方差分析、非配对学生t检验和Fisher最小显著差异检验（P < 0.05）分析界面KIC结果。
在浅表和深层牙本质上，界面KIC结果（单位为MN.m-3/2，括号内为标准差）分别为：全粘结2号，0.80（0.21），0.44（0.13）；粘结它，0.75（0.20），0.38（0.19）；初拌粘结剂，0.56（0.11），0.28（0.10）；3M多功能粘结剂，0.45（0.23），0.26（0.15）；一步法和优化粘结剂，由于试样过早失效，结果不足。
本研究结果应有助于断裂韧性测试作为一种评估牙本质 - 复合材料界面完整性的方法的发展。界面断裂韧性测试确定了不同牙本质粘结剂之间以及浅表和深层牙本质基质之间的显著差异。当粘结到深层牙本质与浅表牙本质时，牙本质粘结剂显示出显著降低的界面断裂韧性结果。
