关键词: 热循环, 剪切强度

Abstract: Objective To evaluate dentin-resin interface on bond strengths under different thermal cycling treatments in vitro. Methods Sixty intact non-carious human molars were selected, the occlusal enamel were removed using a low-speed-saw to expose a dentin surface ,dentin surface were polished with 300 grit，600 grit silicon carbide paper successively. Sixty specimens were divided randomly into three groups according to different thermal cycling treatments, in each group ,two bonding agents were used: Single Bond，a total etch bonding system;and Adper Prompt,a self etch bonding system, with ten teeth in each agent. In group Ⅰ (n=20),there was no thermal cycling treatment ,after preserved in 37℃ water for 24 h,shear bond tests were performed. Another forty specimens were assigned as group Ⅱ (n=20) and group Ⅲ (n=20). Specimens were submitted to thermal cycling, 500 cycles in group Ⅱ and 1 000 cycles in group Ⅲ. The treatment temperature in groups Ⅱand Ⅲ was 5℃-55℃.　The dwell time was 30s in each bath with a transfer time of 20 s. After 24 h storage in distilled water at 37℃, shear bond strength tests were performed. Shear bond strength tests of all groups were conducted in a instron 1121 universal testing machine at a cross-head speed of 1 mm·min^-1 .After shear bond strength test, one of Single Bond fractured specimens and one of Adper Prompt fractured specimen were selected in each group to be examined under SEM. Results Shear bond strengths (MPa)after　0,500 and 1 000 thermal cycles were: Single Bond 18.12±3.36,17.62±3.61 and 16.93±2.66; Adper Prompt:13.22±2.76,12.90±2.93 and 11.17±2.63. There were no significant differences of shear bond strengths among different thermal cycling treatment groups （P>0.05）; Single Bond provided significantly higher shear bond strengths than Adper Prompt in all groups (P<0.05) . All fractures of interfaces showed resin tag create with Single Bond more than with Adper Prompt. Conclusion In short terms,thermal cycling dosen′t influence significantly the shear bond strength of the resin-dentin interface. Compared two dentin-bonding systems used in this study,total etch bond system provide significantly higher strength than self etch bond system.

Key words: shear bond strengths test, thermal cycling