Buchman D J
Am J Orthod. 1980 Jun;77(6):654-68. doi: 10.1016/0002-9416(80)90157-8.
Recycling of metallic direct-bond orthodontic brackets is of current interest to the profession. The methods of three recycling companies (Esmadent, Ortho-Cycle, and Ortho-Bonding) as well as the author's flame method were examined for their effects on bracket base torque, slot width, and mechanical properties. There was no statistically significant difference among the four methods of recycling in terms of change in base torque angle and slot width. A slightly statistically significant number of brackets in the control group had a change in slot width of not more than 0.0015 inch (0.038 mm.), and the number of brackets with any change in slot width was less than 20 percent. The recycling methods of the author and Ortho-Bonding caused a loss of ferromagnetism in the recycled brackets, suggesting annealing of the metal. The effect of thermal treatment on brackets was evaluated by measuring hardness and theoretical tensile strength and by evaluating microstructure. The Ortho-Cycle method did not alter the mechanical properties of the bracket metal while the Esmadent method caused subtle changes. The author's process and the Ortho-Bonding method caused carbode separation. While it appears that the amount of dimensional changes in the brackets is of little clinical significance, the changes in the metallurgic microstructure suggest susceptibility to metallic intergranular corrosion.
金属直接粘结正畸托槽的回收利用是当前该行业关注的问题。研究了三家回收公司（Esmadent、Ortho-Cycle和Ortho-Bonding）的方法以及作者的火焰法对托槽基底扭矩、槽宽和机械性能的影响。在基底扭矩角度和槽宽变化方面，四种回收方法之间没有统计学上的显著差异。对照组中槽宽变化不超过0.0015英寸（0.038毫米）的托槽数量在统计学上略有显著差异，且槽宽有任何变化的托槽数量少于20%。作者和Ortho-Bonding的回收方法导致回收托槽中铁磁性丧失，表明金属发生了退火。通过测量硬度和理论拉伸强度以及评估微观结构来评估热处理对托槽的影响。Ortho-Cycle方法没有改变托槽金属的机械性能，而Esmadent方法引起了细微变化。作者的工艺和Ortho-Bonding方法导致碳化物分离。虽然托槽尺寸变化的量似乎在临床上意义不大，但冶金微观结构的变化表明易发生金属晶间腐蚀。
