表面封闭法对托槽粘接抗剪强度影响的实验研究

目的:研究表面封闭法对托槽粘接抗剪强度(shear bond strength,SBS)的影响.方法:将正畸拔除的20 颗离体前磨牙切割成颊面牙片,用自凝塑料包埋,其颊面经Transbond~(TM) Plus自酸蚀处理液酸蚀30 s后随机等量分为2 组,①实验组:涂Filtek Flow 1400A3流动复合树脂形成封闭层,Transbond~(TM) XT复合树脂粘接托槽;②对照组:Transbond~(TM) XT复合树脂粘接托槽.37 ℃恒温水浴48 h及冷热循环(5 ℃ 30 s,55 ℃ 30 s)1 000 次后,以0.5 mm/min的速度对托槽SBS进行测试;10 倍体视显微镜下观察托槽脱落后牙面树脂残留情况并进行评估.结果:实验组、对照组托槽SBS(Mpa)平均是8.08±1.38、8.34±1.37,牙面树脂残留指数(resin remnant index,RRI)分别是: 2.80±1.03、 3.20±1.03,经检验, 2 组SBS、RRI差异无统计学意义.结论:表面封闭法不影响托槽粘接抗剪强度,能满足固定矫治需要.

Effects of surface sealing on the shear bond strength of the brackets

Objective: To investigate the effects of surface sealing on the shear bond strength(SBS) of the brackets. Methods: Twenty extracted premolars for orthodontics were cut into the buccofacial teeth pieces and etched by Transbond~TM Plus self-etching primers for 30 seconds firstly, then divided into two groups with 10 teeth pieces in each group randomly. ① experiment group, the buccal surface of the enamel was sealed with Filtek Flow 1400A3 flowable composite resin before bracket bonding;②control group, the bracket was bonded to the buccal surface of the enamel directly. All specimens were stored in deionized water at 37 ℃ for 48 h, thermocycled for 1 000 times at 30-second intervals between 5 ℃ and 55 ℃ water baths, and debonded with a universal testing machine. The amounts of resin remaining on the teeth pieces after debonding by using the resin remnant index (RRI), which were examined under 10×magnification stereo-microscope. Results: The SBS(MPa) between experiment group and control group was 8.08±1.38, 8.34±1.37 respectively, whereas the RRI was 2.80±1.03, 3.20±1.03 respectively. The SBS, RRI between experimental group and control group revealed no statistically significant differences. Conclusion: Surface sealing shows adequate bond strength, which is considered a clinically acceptable bond strength. The debonding of bracket is not affected by the surface sealing.