托槽重复黏结及不同处理方法对抗剪强度的影响

Influence of rebonded orthodontic brackets and different treatment methods on shear bond strength

目的:观察正畸托槽脱落后第2、3次黏结时托槽底板残留黏结剂的不同处理方法对抗剪强度的影响。方法:选择60颗离体人前磨牙,随机分成3组,每组20个样本,第1组为更换新托槽组(简称更新组),即在第2、3次黏结时分别更换新托槽;第2组为燃烧去除底板残胶组(简称燃烧组),即在进行第2、3次黏结时对托槽底板上的残留黏结剂进行燃烧处理;第3组为磨除法去除底板残胶组(简称磨除组),即在第2、3次黏结时对托槽底板上的黏结剂进行磨除处理。3组分别按常规操作对黏结托槽进行剪切试验,记录每组抗剪强度数值的变化并观察ARI指数(牙面残留黏结剂指数)。结果:3组托槽初次黏结的抗剪强度分别(10.00±2.95)MPa;(9.57±2.45)MPa;(9.09±2.58)MPa;更新组第2、3次黏结的抗剪强度分别为(9.55±2.84)MPa;(10.32±2.59)MPa。燃烧组第2、3次黏结抗剪强度分别为(7.30±2.15)MPa;(7.14±1.93)MPa;磨除组的第2、3次黏结抗剪切强度分别为(12.13±2.93)MPa;(12.86±3.08)MPa;燃烧组抗剪强度下降,磨除组抗剪强度则升高,两者均有统计学意义。结论:黏结脱落托槽时宜采用磨除法对脱落托槽底板上残留的黏结剂进行处理,避免使用燃烧底板残胶的方法。

Objective：To compare shear bond strength（SBS） of bonded and rebonded orthodontic brackets and influence of rebonded orthodontic brackets using different treatment methods on SBS. Methods： 60 extracted premolars were evenly divided into three groups. Brackets were debonded with conventional techniques and then removed of residual adhesives from the base mesh using three different treatments. In group Ⅰ , rebond a new bracket at the second, third bonding times. In group Ⅱ , remove residual adhesives from the base mesh with fire at the second, third times, then rebond the same bracket. In group Ⅲ, remove that using a tungsten carbide bur at the second, third times, then rebond the same bracket. Shear test was performed to compare the SBS and adhesive remnant indexes（ARI） among different groups. Results：The SBS of three groups at the first bonding sequence were （ 10.00 ± 2.95 ） MPa, （9.57 ± 2.45） MPa and （9.09±2.58） MPa. The SBS at the second, third debonding sequence in group Ⅰ, group Ⅱ, and group Ⅲ were （9.55 ±2.84） MPa and （10.32 ±2.59） MPa, （7.30 ±2. 15） MPa and （7. 14 ± 1.93） MPa, （ 12.13 ± 2.93 ） MPa and （ 12.86 ±3.08 ） MPa, respectively. In group Ⅱ, the SBS was significantly lower, however, in group Ⅲ, the SBS was significantly higher, and the results showed significant differences（ P 〈0.05 ）. Conclusion ：The data suggest that the optimal procedure to remove residual adhesives from the base mesh of bracket to get the greatest shear bond strength is using a tungsten carbide bur.