Evaluation of pH, ultimate tensile strength, and micro-shear bond strength of two self-adhesive resin cements

The aim of this study was to evaluate the pH, ultimate tensile strength (UTS), and micro-shear bond strength (µSBS) of two self-adhesive resin cements to enamel and dentin. Sound bovine incisors (n = 10) and two self-adhesive resin cements (i.e., RelyX U-100 and seT PP) were used. The pH of the resin cements was measured using a pH-indicator paper (n = 3). Specimens for UTS were obtained from an hourglass-shaped mold. For µSBS, cylinders with internal diameter of 0.75 mm and height of 0.5 mm were bonded to the flat enamel and dentin surfaces. Bonded cylinders were tested in the shear mode using a loop wire. The fracture mode was also evaluated. The cement seT PP showed a low pH; U-100 showed significantly higher UTS (49.9 ± 2.0) than seT PP (40.0 ± 2.1) (p < 0.05) and high µSBS to enamel (10.7 ± 3.7). The lowest µSBS was found for seT PP to dentin (0.7 ± 0.6); seT PP to enamel (4.8 ± 1.7), and for U-100 to dentin (7.2 ± 1.9), showing an intermediate µSBS value (p < 0.05). Adhesive failure was the most frequently observed failure mode. The resin cement that presented the lowest pH and UTS also presented the lowest micro-shear bond strength to enamel and dentin.

本研究旨在评估两种自粘结树脂粘接剂（self-adhesive resin cements）对牙釉质与牙本质的pH值、极限抗拉强度（ultimate tensile strength, UTS）以及微剪切粘结强度（micro-shear bond strength, µSBS）。实验采用健康牛切牙（n = 10）以及两种自粘结树脂粘接剂，即RelyX U-100与seT PP。使用pH指示剂试纸（n = 3）测定树脂粘接剂的pH值。极限抗拉强度试样通过沙漏形模具制备。针对微剪切粘结强度测试，将内径0.75 mm、高度0.5 mm的圆柱体粘接至平整的牙釉质与牙本质表面，采用环形钢丝以剪切模式对粘接后的圆柱体进行强度测试，并评估其断裂模式。seT PP树脂粘接剂呈现较低pH值；U-100的极限抗拉强度（49.9 ± 2.0）显著高于seT PP（40.0 ± 2.1）（p < 0.05），且其对牙釉质的微剪切粘结强度较高（10.7 ± 3.7）。seT PP对牙本质的微剪切粘结强度最低（0.7 ± 0.6）；seT PP对牙釉质（4.8 ± 1.7）与U-100对牙本质（7.2 ± 1.9）的微剪切粘结强度处于中间水平，组间差异具有统计学意义（p < 0.05）。粘接失效是最常见的断裂模式。pH值与极限抗拉强度最低的树脂粘接剂，其对牙釉质与牙本质的微剪切粘结强度也最低。