Abstract:

Objective     To investigate the effect of irradiation with Nd∶YAG laser on the surface microstructure and temperature change of dental implants in vitro，in order to provide the reference for clinical parameter setting and operation method. Methods    The titanium discs were irradiated by Nd∶YAG laser with different parameter setting. The surface microstructure was observed by scanning electron microscope， and the temperature elevation was measured by thermocouple. The time to reach a 10℃ increase in temperature was recorded as well. Results    （1）Local areas with surface melting on 0.2W （20 mJ，10 Hz）and significant melting with crackson 1W setting （100 mJ，10 Hz or 50 mJ，20 Hz） were observed after Nd∶YAG laser irradiation without cooling，while the surface of the titanium disk is still molten with water vapor cooling.（2）The temperature elevation of titanium discs were less than 10℃ with low power setting or water cooling conditions of Nd∶YAG laser irradiation for 30 seconds. It took 13.8，6.2 and 7.8 seconds，respectively，to reach a 10℃ increase threshold in temperature after being irradiated with 0.5 W （50 mJ，10 Hz）and 1W（100 mJ，10 Hz or 50 mJ，20 Hz）without cooling conditions. Conclusion    Direct and prolonged exposure to Nd:YAG laser leads to microstructure change of implant surface，and may produce a risk of thermal damage to surrounding tissue. The reasonable parameter setting，mobile radiation mode and cooling are suggested.

Key words: Nd∶YAG laser, surface, temperature, peri-implantitis

摘要：

目的    研究Nd∶YAG激光照射对种植体表面结构和温度变化的影响，以期为临床应用该激光时的参数设置和操作方法提供依据。方法    应用波长1064 nm的脉冲Nd∶YAG激光照射与临床实际应用种植体相同表面处理的纯钛圆盘试件，设定不同参数和条件，扫描电镜观察钛盘表面结构变化，热电偶检测钛盘温度变化范围和到达骨组织损伤温度升高阈值（升高10 ℃）的照射时长。结果    （1）无水气冷却条件下，无论是定点照射5 s还是移动照射30 s，激光参数为0.2 W（20 mJ，10 Hz）时，钛盘表面均出现局限性熔融变化，移动照射时变化程度轻；激光参数为1 W（100 mJ，10 Hz或50 mJ，20 Hz）时，钛盘表面均出现熔融并伴裂纹。在有水气冷却的条件下，钛盘表面仍有熔融改变。（2）激光参数为0.2 W（20 mJ，10 Hz）、无水气冷却条件下或激光参数为0.5 W（50 mJ，10 Hz）和1W（50 mJ，20 Hz或100 mJ，10 Hz）、有水气冷却条件下，移动照射钛盘表面30 s，其表面温度升高均不超过10℃。无水气冷却条件下，激光参数分别为0.5 W（50 mJ，10 Hz）、1 W（50 mJ，20 Hz）和1 W（100 mJ，10 Hz）移动照射钛盘表面30 s，其表面温度变化达骨组织损伤温度升高阈值的照射时长分别为13.8、6.2和7.8 s。结论    Nd∶YAG激光直接照射种植体表面可引起表面结构明显变化和周围组织热损伤风险，应注意合理参数设置、移动照射操作和冷却。

关键词: Nd∶YAG激光, 表面, 温度, 种植体周围炎