Mojtahedzadeh Faramarz, Akhoundi Mohammad Sadegh Ahmad, Noroozi Hassan
Department of Orthodontics, Kerman School of Dentistry, Kerman, Iran.
Am J Orthod Dentofacial Orthop. 2006 Sep;130(3):385-7. doi: 10.1016/j.ajodo.2006.03.021.
The purpose of this study was to compare 2 common methods of measuring orthodontic shear bond strength.
Brackets were bonded to 40 bovine incisors, and the teeth were mounted in a jig. The teeth were paired for symmetry, and the pairs were divided into 2 groups for debonding. In group 1, the shear force was applied with a rectangular wire under the tie wings. In group 2, a shearing blade applied force to the junction between the bracket base and the adhesive.
Debonding with the shear blade produced higher (24.86 +/- 7.44 MPa) and more dispersed (coefficient of variation = 29.91%) bond strengths compared with the wire loop (17.12 +/- 3.16 MPa, coefficient of variation = 18.44%). Adhesive remnant index (ARI) scores showed a tendency for cohesive failure in the enamel in the shear-blade group (ARI = 5) compared with adhesive failure (ARI = 3) in the wire group.
There is a need to standardize bond strength tests. The results of this study favor the wire-loop method, which might have more similarity to clinical loads. The regression formula might make comparison of previous studies easier.
本研究的目的是比较两种常用的测量正畸剪切粘结强度的方法。
将托槽粘结到40颗牛切牙上，并将牙齿安装在夹具中。牙齿按对称性配对，然后将配对的牙齿分为两组进行脱粘。在第1组中，在结扎翼下方用矩形丝施加剪切力。在第2组中，用剪切刀片对托槽底座与粘合剂之间的结合处施加力。
与丝圈法（17.12±3.16MPa，变异系数=18.44%）相比，使用剪切刀片进行脱粘产生的粘结强度更高（24.86±7.44MPa）且更分散（变异系数=29.91%）。粘结剂残留指数（ARI）评分显示，与丝圈组的粘结剂破坏（ARI=3）相比，剪切刀片组的釉质内聚破坏趋势（ARI=5）。
需要对粘结强度测试进行标准化。本研究结果支持丝圈法，该方法可能与临床负荷更相似。回归公式可能会使以往研究的比较更容易。
