Zarif Najafi Hooman, Bagheri Rafaat, Pakshir Hamid Reza, Tavakkoli Mohammad Amin, Torkan Sepideh
Orthodontic Research Center, Department of Orthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Dental Material Department and Biomaterials Research Center, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Int Orthod. 2019 Mar;17(1):73-79. doi: 10.1016/j.ortho.2019.01.008. Epub 2019 Feb 13.
The aim of this study was to determine the effect of bleaching and desensitizing on shear bond strength (SBS) of metal brackets to enamel.
One hundred extracted human premolar were randomly assigned to 5 groups of 20. In the first group (control), no bleaching or desensitizing agent was used. Groups 2 to 5 were bleached with 37.5% hydrogen peroxide and desensitized with 6.0% potassium nitrate. Surface treatment comprised of etching for 15seconds in groups 1, 2 and 3, Er:yag laser irradiation and etching in group 4 and sandblasting and etching in group 5. Premolar brackets were bonded with Transbond XT and cured for 20seconds and the SBS was tested using a universal testing machine. Adhesive remnant index (ARI) score was used to record the mode of bond failure.
No significant difference was found between the mean SBS (MPa) in groups 1(15.22), 4(14.02), and 5(12.62). SBS in group 4 was significantly higher than group 2 (8.15) (P<0.001). Also, SBS in groups 2 (P<0.001) and 3(11.74) (P=0.012) were significantly lower than group 1. An increased frequency of ARI score of 2 and 3 was observed in groups 1, 4 and 5.
Bleaching plus desensitizing significantly decreased the SBS of orthodontic brackets. Delaying the bonding procedure for at least 2 weeks or alternative surface treatment methods such as combined laser and acid etching or combined sand blasting and acid etching can improve the SBS.
本研究的目的是确定漂白和脱敏对金属托槽与牙釉质之间剪切粘结强度（SBS）的影响。
将100颗拔除的人类前磨牙随机分为5组，每组20颗。第一组（对照组）不使用漂白剂或脱敏剂。第2至5组用37.5%的过氧化氢漂白，并用6.0%的硝酸钾脱敏。表面处理包括：第1、2和3组酸蚀15秒，第4组Er:YAG激光照射后酸蚀，第5组喷砂后酸蚀。用Transbond XT粘结前磨牙托槽并固化20秒，然后使用万能试验机测试SBS。用粘结剂残留指数（ARI）评分记录粘结失败模式。
第1组（15.22）、第4组（14.02）和第5组（12.62）的平均SBS（MPa）之间无显著差异。第4组的SBS显著高于第2组（8.15）（P<0.001）。此外，第2组（P<0.001）和第3组（11.74）（P=0.012）的SBS显著低于第1组。在第1、4和5组中观察到ARI评分为2和3的频率增加。
漂白加脱敏显著降低了正畸托槽的SBS。将粘结程序推迟至少2周或采用联合激光和酸蚀或联合喷砂和酸蚀等替代表面处理方法可提高SBS。
