Mundstock K S, Sadowsky P L, Lacefield W, Bae S
University of Alabama at Birmingham, Department of Orthodontics, Birmingham, USA.
Am J Orthod Dentofacial Orthop. 1999 Dec;116(6):635-41. doi: 10.1016/s0889-5406(99)70198-8.
The objectives of the present study were to measure and compare the bond strength and failure sites of a currently available ceramic bracket (Transcend 3M-Unitek) with the new metal reinforced ceramic bracket (Clarity 3M-Unitek) and to evaluate the amount of composite left on the tooth using the Adhesive Remnant Index in the teeth that were debonded with pliers recommended for this purpose. In addition, the presence or absence of enamel damage after debonding was also assessed. One hundred and twenty extracted premolar teeth were divided into 4 groups of 30 each. Two groups of 30 teeth had Transcend 6000 brackets bonded, and the other 2 groups had Clarity brackets bonded. Shear bond strength was carried out on 30 Transcend 6000 brackets and 30 Clarity brackets, whereas the other 2 groups of 30 teeth bonded with Transcend 6000 and Clarity brackets were debonded with debonding pliers recommended by the manufacturer of both ceramic brackets. The mean shear bond strength of the Clarity brackets was 13.27 MPa, whereas that of the Transcend 6000 was 21.19 MPa. Both brackets failed mostly at the bracket-adhesive interface (75%), indicating a possible reduction of the chances of enamel damage. Six of the premolars, bonded with Transcend 6000 brackets and debonded with the plier, showed an increase in the number or length of enamel cracks as evaluated by an optical microscope (Micro-Vu); one premolar, bonded with Clarity brackets and debonded with the pliers, showed an increased enamel crack length. Gross enamel damage, assessed by enamel dislodgment, was not evident in any specimen. Results of this study suggest that the new metal reinforced ceramic bracket (Clarity) may be recommended for clinical use because of its acceptable shear bond strength and possible reduced chances of enamel damage during bracket removal.
本研究的目的是测量并比较一种市售陶瓷托槽（3M - Unitek公司的Transcend）与新型金属增强陶瓷托槽（3M - Unitek公司的Clarity）的粘结强度和失效部位，并使用粘结剂残留指数评估用为此目的推荐的钳子进行脱槽的牙齿上残留的复合树脂量。此外，还评估了脱槽后釉质损伤的情况。120颗拔除的前磨牙被分为4组，每组30颗。两组30颗牙齿粘结了Transcend 6000托槽，另外两组粘结了Clarity托槽。对30个Transcend 6000托槽和30个Clarity托槽进行剪切粘结强度测试，而另外两组分别粘结有Transcend 6000和Clarity托槽的30颗牙齿则用两种陶瓷托槽制造商推荐的脱槽钳进行脱槽。Clarity托槽的平均剪切粘结强度为13.27MPa，而Transcend 6000托槽的平均剪切粘结强度为21.19MPa。两种托槽大多在托槽 - 粘结剂界面处失效（75%），这表明釉质损伤的可能性可能会降低。在6颗粘结有Transcend 6000托槽并用钳子脱槽的前磨牙中，通过光学显微镜（Micro - Vu）评估发现釉质裂纹的数量或长度有所增加；1颗粘结有Clarity托槽并用钳子脱槽的前磨牙，其釉质裂纹长度增加。通过釉质脱落评估的明显釉质损伤在任何标本中均未出现。本研究结果表明，新型金属增强陶瓷托槽（Clarity）因其可接受的剪切粘结强度以及在托槽拆除过程中釉质损伤可能性可能降低，或许可推荐用于临床。
