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目的探讨多次黏结对金属托槽槽沟及其滑动摩擦力的影响。方法本研究于2004年9月至2006年3月在福建医科大学附属口腔医院及福州大学测试中心进行。选择因正畸治疗拔除的上颌双尖牙40颗,MBTTM迷你直丝弓托槽10个,采用高温灼烧后电解抛光的方法处理脱落的金属托槽,对托槽进行多次黏结。扫描电镜下观察槽沟底金属表面结构的变化,并检测托槽宽度和槽沟宽度。应用三角函数的原理推算出托槽弓丝接触角θc的公式,分别计算出多次黏结前后托槽指数、入槽指数及θc的变化。结果随着黏结次数的增加,槽沟底金属表面结构愈显粗糙;托槽宽度逐渐减小,与首次黏结相比,第二次黏结的变化无统计学意义(P>0.05),第三、第四次黏结的变化具有统计学意义(P<0.01)。随着黏结次数的增加,槽沟宽度、θc均依次增大,托槽入槽指数、托槽指数显著减小,与首次黏结相比,各组差异均有统计学意义(P<0.01)。结论入槽指数的减小虽然有利于缓解滑动阻力,但多次黏结会引起金属托槽槽沟表面粗糙、托槽弓丝接触角θc增大,均有可能导致槽沟滑动摩擦力增加,因此,在正畸临床矫治过程中对托槽的多次黏结应慎重。而托槽指数的变化对托槽与弓丝间滑动摩擦力的影响还有待于进一步的研究。
Objective To explore the effect of multiple bonding on the groove and sliding friction of metal bracket. Methods The study was conducted from September 2004 to March 2006 at the Affiliated Stomatological Hospital of Fujian Medical University and the Fuzhou University Test Center. Choose 40 maxillary bicuspids extracted by orthodontic treatment, 10 MBTTM mini linear arch brackets, use high-temperature burning and electropolishing method to dispose of the dropped metal bracket, and bond the bracket several times. Under the scanning electron microscope, the change of the surface structure of the groove bottom metal was observed, and the width of the bracket and the width of the groove were measured. Applying the principle of trigonometric function, the formula of the contact angle θc of the arch wire of the bracket is deduced, and the change of bracket index, slot index and θc before and after multiple bond are calculated respectively. Results With the increase of the number of bonding, the surface structure of the grooved bottom metal became more rough. The width of the bracket decreased gradually. Compared with the first bonding, the second bonding showed no statistical significance (P> 0.05) The fourth change of adhesion was statistically significant (P <0.01). With the increase of the number of bonding, the width of groove and θc increased in turn, the index of bracket slotting and bracket index decreased significantly. Compared with the first bonding, the difference of each group was statistically significant (P <0.01). Conclusions Although the reduction of the slot index can help to reduce the sliding resistance, the multiple bonding will cause the surface of the metal bracket groove to be rough and the contact angle θc of the bracket wire increases, which may increase the sliding friction of the groove. , In orthodontic clinical treatment of the brackets repeatedly bonded should be careful. The change of bracket index on the sliding friction between the bracket and arch wire remains to be further studied.