中文摘要：

正畸托槽广泛应用于牙齿正畸临床治疗中。但由于诸多因素，粘结后的托槽时常会发生脱落现象，需要回收清洗，重新粘结。采用皮秒激光（波长为532nm和1064nm；脉宽小于20ps）对MiniSprint金属正畸托槽进行了激光清洗研究，有效地解决了常规激光清洗中因入射光边缘衍射效应而导致柱状固位结构周缘粘结剂残留的问题，实现托槽的完全清洗。确认高频断续超短脉宽的脉冲作用在材料中形成的热弹性波以力学振动传播扩散的方式是实现皮秒激光完全清洗的主要机制，该机制不同于常规激光清洗的热蒸发机制。发现不同波长皮秒激光清洗后的托槽固位结构单元顶端的表面形貌存在差异，因托槽制作工艺引入的表面本征缺陷在较短波长532nm皮秒激光的辐照下，因表面等离子振荡效应的激发，而导致局域电磁场能量增强，形成有利于托槽粘结的微坑结构。

英文摘要：

Bracket bonding technology is widely applied in clinical orthodontic practice. However, orthodontic bracket sheds off frequently due to various reasons which results in the advocating of recycling utilization of the brackets by refurbishing. In this study, the refurbishing of Mini Sprint stainless bracket by picosecond laser （wavelengths of 532 nm and 1064 nm, pulse width： 〈20 ps） is studied. High clean quality without any resin adhesive is achieved which overcome the limitation of edge diffraction effect during conventional laser cleaning technique. There is an evidence that the diffusion of the stress vibration due to the elastic waves generated by ultra short pulse shots with high frequency is the picosecond laser cleaning mechanism. It is observed that there are differences between the microstructure on the top of columnar bracket base refurbished by picosecond lasers with different wavelengths. It is suggested that localized surface polaritons （LSPs） induced by the original point defects on bracket base surface under the irradiation of 532 nm picosecond laser enhance the energy distribution of laser input, which results in the formation of micro-pit structures on the bracket surface beneficial for the rebonding.