Er:YAG激光去除Zenostar T全瓷冠的能量评估方法研究

Energy assessment of Zenostar T all-ceramic crown removal using Er:YAG laser

目的评估Er:YAG激光作用于不同厚度Zenostar T全瓷修复样品后的温度变化情况,探讨激光能量、材料厚度和温度变化之间的相关性,为临床使用Er:YAG激光去除Zenostar T全瓷冠提供初步的依据与指导。方法选择Zenostar T全瓷修复材料,制成长和宽均为10 mm,厚度分别为1.0 mm、1.5 mm、2.0 mm、2.5 mm和3.0mm的样品(n=3)。使用X线能谱(EDS)和傅里叶变换红外光谱(FTIR)检测样品的化学元素和化学基团组成;利用扫描电镜(SEM)观察Er:YAG激光照射全瓷修复样品前后表面形态改变。Er:YAG激光波长为2940 nm,频率15 Hz,脉宽330μs,光斑直径1 mm,对不同厚度样品进行垂直照射,单次照射持续5 s,不同位置重复照射3次,用激光功率计和热电偶温度计测量激光穿透样品后的能量和温度变化情况。结果实验组激光能量在50 mJ、100 mJ、150 mJ时,能量结果的指数曲线r2分别为0.9997、0.9973、0.9790;温度结果的指数曲线r2分别为0.9883、0.9868和0.9950;能量和温度与样品厚度均符合指数函数关系。SEM结果表明激光照射会对样品造成一定程度的损伤。结论Er:YAG激光去除Zenostar T全瓷冠时,可依据实验结果中的指数拟合曲线,初步估算安全的激光能量。

Objective Improper energy setting may cause irreversible damage to oral tissue when Er:YAG laser was used to remove all-ceramic crowns.This study aimed to evaluate the temperature variation in Zenostar T samples of different thicknesses irradiated by Er:YAG laser,investigate the relationship between the changes in laser energy,material thickness,and temperature,and provide preliminary energy selection guidance for clinical practice in using Er:YAG laser to remove Zenostar T all-ceramic crowns.Methods All samples used in this experiment were Zenostar T all-ceramic materials,which were cut into squares of 10 mm×10 mm with thicknesses of 1.0 mm,1.5 mm,2.0 mm,2.5 mm,and 3.0 mm.Three samples of each thickness group were prepared.The chemical elements and groups of the samples were analyzed by X-ray energy spectroscopies and FTRI.SEM was used to observe the sample surface morphology changes before and after laser irradiation.Er:YAG laser with a wavelength of 2940 nm,a repetition rate of 15 Hz,and a pulse duration of 330μs was used.The laser spot diameter was 1.0 mm,and the laser irradiation duration was 5 s each time.The laser energy was irradiated three times at different positions of each sample,and the energy and temperature of the laser after penetrating the sample was recorded each time.Results With the increase of the laser energy,the r2 of energy results in the experiment groups were 0.9997、0.9973、0.9790,and the r2 of temperature results were 0.9883、0.9868、0.9950.The research showed that energy and temperature had an exponential fitting curve relationship with the sample thickness under the same energy.The SEM results showed that the structure of Zenostar T samples was damaged by laser irradiation.Conclusions When all ceramic crowns will be removed by Er:YAG laser,laser energy can be preliminarily estimated on the basis of the exponential curve fitted in the experimental results.