Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla, 9-75, Bauru, SP, 17012-901, Brazil.
Departament of Prosthodontics, University Of Western São Paulo, José Bongiovani Street, 700 - Cidade Universitária, Pres. Prudente - SP, 19050-920, Brazil.
Dent Mater. 2018 Nov;34(11):1690-1701. doi: 10.1016/j.dental.2018.08.302. Epub 2018 Sep 13.
To evaluate and compare the outcomes of shear (S) and microtensile (μT) bond strength tests of CAD/CAM fiber-reinforced composite (FRC) to dentin. Aging with either fatigue or thermocycling were conducted for comparison with baseline microtensile group.
CAD/CAM FRC (Trinia, Bicon LLC, Boston, USA) blocks were milled to 3-mm diameter cylinders for shear and to blocks (5×5×5mm) for μT. Sixty extracted human molars were flattened to obtain dentin surfaces and randomly divided in four groups (n=15): (1) SC: samples tested in shear 24h after bonding; (2) μTC: samples tested in μT 24h after bonding); (3) μTF: samples submitted to mechanical fatigue prior to μT test, and; (4) μTT: thermocycling prior to μT test. Bonding system was applied onto the FRC material (Cera-Resin Bond, CRB, Shofu Dental, Kyoto, Japan). A conventional three-step adhesive system (All-bond 3, Bisco, Schaumburg, USA) was use with a self-cure resin cement (C&B resin cement, Bisco, Schaumburg, USA). Bond strength tests were conducted at 0.75mm/min and data analyzed using Weibull distribution (p<0.05).
Weibull contour plots showed a significantly lower characteristic strength (η) and Weibull modulus (m) for SC (η=6.9MPa and m=1.4) compared to μTC (η=20.9MPa and m=4.5). Fatigued and thermocycled μT groups presented significantly reduced characteristic strength (η=3.1MPa and η=4.1MPa, respectively) compared to μTC. Weibull modulus was significantly reduced only for SC and μTF groups compared μTC. Failure predominantly occurred at the cement/FRC interface.
FRC bonded to dentin samples presented lower Weibull modulus and characteristic bond strength when immediately tested in shear compared to microtensile. Aging through thermocycling or mechanical fatigue significantly reduced the characteristic strength in microtensile testing, with the majority of failures emerging between restoration material and cement interface.
评估和比较 CAD/CAM 纤维增强复合材料（FRC）与牙本质的剪切（S）和微拉伸（μT）结合强度测试的结果。进行疲劳或热循环老化与基线微拉伸组进行比较。
将 CAD/CAM FRC（Trinia，Bicon LLC，波士顿，美国）块铣削成 3mm 直径的圆柱体进行剪切，铣削成 5×5×5mm 的块进行 μT。从 60 颗人磨牙中取出牙本质表面并随机分为 4 组（n=15）：（1）SC：粘接后 24 小时进行剪切测试的样品；（2）μTC：粘接后 24 小时进行 μT 测试的样品；（3）μTF：在 μT 测试前进行机械疲劳的样品；（4）μTT：在 μT 测试前进行热循环的样品。粘接系统应用于 FRC 材料（Cera-Resin Bond，CRB，Shofu Dental，京都，日本）。使用传统的三步粘接系统（All-bond 3，Bisco，Schaumburg，美国）和自固化树脂水泥（C&B 树脂水泥，Bisco，Schaumburg，美国）。在 0.75mm/min 下进行粘接强度测试，并使用 Weibull 分布进行数据分析（p<0.05）。
Weibull 轮廓图显示，与 μTC（η=20.9MPa，m=4.5）相比，SC（η=6.9MPa，m=1.4）的特征强度（η）和 Weibull 模数（m）明显较低。与 μTC 相比，疲劳和热循环 μT 组的特征强度明显降低（η=3.1MPa 和 η=4.1MPa）。仅与 μTC 相比，SC 和 μTF 组的 Weibull 模数显著降低。失效主要发生在水泥/FRC 界面。
与微拉伸相比，直接剪切测试时，粘接至牙本质的 FRC 样品的 Weibull 模数和特征粘接强度较低。通过热循环或机械疲劳老化会显著降低微拉伸测试中的特征强度，大多数失效出现在修复材料和水泥界面之间。
