底板形态和粘结时间对托槽粘结强度的影响

Influence of base forms and bond time on the shear bond strength of orthodontic brackets

目的对目前正畸临床上最常用的金属网底托槽和微蚀刻底托槽的粘结强度进行对比分析,并确定力加载的适宜时间。方法选取正畸临床上减数拔除的上颌第一前磨牙120颗,随机分为2组,第1组粘结金属网底托槽,第2组粘结金属微蚀刻底托槽。每组分别在粘结后5 min、10 min、15 min、30 min、60 min、24 h测定抗剪切强度(SBS),并统计粘结剂残留指数(ARI),电镜扫描托槽粘结前、脱落后底板形貌。结果金属网底托槽组和微蚀刻底托槽组SBS均随粘固时间的延长而增大,24 h时粘结强度最大,且与其他时间点有统计学差异(P<0.05)。结论两种金属托槽的粘结强度均能满足临床需要,可在托槽粘结后5 min进行正畸力的加载。

Objective To find the appropriate time to load the bracket by comparing the shear bond strengths （SBS） of two kinds of brackets with different bases. Methods One hundred and twenty extracted youth first premolars were di- vided into 2 groups randomly. The standard straight wire brackets with spherical mesh base and etching base were used in the 2 groups respectively. The SBS test for the 2 groups was performed at different debond times of 5, 10, 15, 30 and 60 minutes and 24 hours. The chi-squared test was also used to determine the significant differences for the adhesive remnant index （ARI） scores between the 2 groups. Scanning electronic microscope was used to observe the shape of the brackets with different bases before bonding and after debonding from teeth. Results The highest shear bond strength was obtained at the debond time of 24 hours for the both kinds of metal brackets, which had significant difference than those at other times （ P 〈 0.05）. Conclusion The both kinds of metal brackets are strong enough to meet the clinical needs. It is reliable to load the bracket 5 minutes after it is bonded.