不同参数的Er:YAG激光离体牙窝洞预备的形态学观察

Morphological changes of dental hard tissues irradiated by Er:YAG laser with different parameters:an in vitro study

目的:观察Er:YAG激光对离体人牙进行窝洞预备后的形态学改变,比较不同的能量设置及不同的水气比作用下的预备效果。方法:将10个无龋的离体磨牙随机分为5组(n=2),分别用不同Er:YAG激光参数进行窝洞预备。扫描电镜下观察牙釉质和牙本质的形态学改变。结果:经Er:YAG激光照射后,牙釉质呈现出一个粗糙不平的表面,牙本质层清洁,小管开放。在总功率相近的情况下,当水冷却降到50%或切割牙釉质时脉冲能量增加到700 mJ、切割牙本质时脉冲能量增加到400 mJ时,牙釉质及牙本质表面可发生部分熔融改变。结论:Er:YAG激光使用合适的参数进行牙体硬组织的切割安全有效,但在功率相近的情况下,水冷却不足或能量过大(牙釉质>700 mJ,牙本质>400 mJ)可损伤牙体组织。

AIM To observe the morphological changes of dental hard tissues irradiated by Er：YAG laserwith different parameters .METHODS：10 extracted caries-free human molars were randomly divided into 5 groups（n =2）and were prapred by Er：YAG laser with 200 mJ/40 Hz/8 W/100%water for enamel and 100mJ/40Hz/4W/100%water for dentin（group 1）.400 mJ/20 Hz/8 W/100%water for enamel and 200 mJ/20 Hz/4W/100%water fordentin（group 2）.400 mJ/20 Hz/8 W/50%water for enamel and 200 mJ/20 Hz/4 W/50%water for dentin（group3）.400 mJ/20 Hz/8 W/100% water for enamel and 300 mJ/15 Hz/4.5 W/100% water for dentin （group4 ）.700 mJ/10 Hz/7W/100%water for enamel and 400 mJ/10 Hz/4 W/100% water for dentin（group 5）,respectively.After preparation,the samples were observed under SEM.RESULTS：The enamel showed a clear rough surface aftertreatment,the dentin showed open dentinal tubules and no smear layer.But when water spray decreased to 50% or thepulse energy increased to 700 mJ for enamel and 400 mJ for dentin,melting areas were detected.CONCLUSION：Appropriate parameters of Er：YAG laser is safe and effective for dental hard tissue ablation.Under the same power setting,insufficient water spray or too high pulsing energy can damage the hard tissue.