Abstract: Objective    To investigate the effects of Er∶YAG laser surface treatment on the color and transparency of the glass ceramics. Methods    Totally 50 rectangle-shaped ceramic（IPS e.max Press HT）specimens（22.0 mm × 5.0 mm × 1.2 mm）were fabricated and randomly divided into 5 groups（n = 10），including 4 laser groups with different energy（2W，3W，4W and 5W）and 1 control group. The specimens of each laser group were treated with Er∶YAG laser with corresponding parameters for 30 s，60 s and 90 s and recorded as 30 s，60 s and 90 s subgroups. The control group did not receive surface treatment. The color parameters（L*，a*，b* values），color difference（ΔE）and transparency（TP）of each group were measured and compared. Results    ①There were significant differences in L* and TP values between each 5W laser subgroups and control group （P < 0.05）. There were significant differences in TP values between each 5W and each 4W laser subgroups and control group （P < 0.05）. No significant differences in color indexes were found between other laser subgroups and control group （P > 0.05）. ② The values of L*，a*，b*，ΔE and TP in different treatment time subgroups of each laser group were compared，and no significant differences were found （P > 0.05）. ③When the treatment time was 30 s，the TP value of 2W，3W and 4W laser groups was higher than that of 5W laser group，and the TP value of 2W laser group was higher than that of 4W laser group. When the treatment time was 60 s，the TP values of 3W，4W and 5W laser groups were lower than those of 2W laser group. When the treatment time was 90 s，the TP values of 2W，3W and 4W laser groups were higher than those of 5W laser group，and the L* values of 2W and 3W laser groups were lower than those of 5W laser group. The above differences were statistically significant（P < 0.05）. Conclusion    Er∶YAG laser surface treatment affects the color and transparency of the glass ceramics. Doctors should pay attentions to the influence of the Er∶YAG laser on the esthetic effect of ceramic restorations.

Key words: Er∶YAG laser, surface treatment, glass ceramics, color, transparency

摘要： 目的    研究Er∶YAG激光表面处理方法对玻璃陶瓷材料颜色和透明度的影响。方法    使用IPS E.max Press HT瓷块制作成50个长方形试件（22.0 mm × 5.0 mm × 1.2 mm），并随机分为5组，包括4个不同能量（2W、3W、4W和5W）激光组和1个对照组，每组10个试件。采用相应参数的Er∶YAG激光处理各激光组试件30、60、90 s，并记为30、60、90 s亚组；对照组不做表面处理。测量并比较各组颜色参数（L*、a*、b*值）、色差（ΔE）值和透明度（TP）值差异。结果    ①5W激光组不同处理时间亚组的L*值与对照组比较，差异均有统计学意义（均P < 0.05）；其TP值及4W激光组不同处理时间亚组的TP值与对照组比较，差异也均有统计学意义（均P < 0.05）。其他激光组不同处理时间亚组的测量指标与对照组比较，差异均无统计学意义（均P > 0.05）。②对各激光组不同处理时间亚组的L*、a*、b*、ΔE、TP值进行比较发现，差异均无统计学意义（均P > 0.05）。③当处理时间为30 s时，2W、3W、4W激光组的TP值均大于5W激光组，且2W激光组的TP值大于4W激光组；当处理时间为60 s时，3W、4W、5W激光组的TP值均小于2W激光组；当处理时间为90 s时，2W、3W、4W激光组的TP值均大于5W激光组，且2W、3W激光组的L*值均小于5W激光组，以上差异均有统计学意义（均P < 0.05）。结论    Er∶YAG激光表面处理会造成玻璃陶瓷材料颜色和透明度的改变，在临床应用中需要注意其对玻璃陶瓷修复体美学效果的影响。

关键词: Er∶YAG激光, 表面处理, 玻璃陶瓷, 颜色, 透明度