基于X射线衍射的激光消融改变人牙本质表层晶体结构的研究

Study on Crystal Structure Change of Laser-Ablated Human Dentin Surface Based on X-Ray Diffraction

利用X射线衍射仪(XRD)研究了Er,Cr∶YSGG激光消融对人牙本质表层晶体结构的影响。采用不同能量密度的Er,Cr∶YSGG激光消融人牙本质,然后利用XRD分析了激光照射前后牙本质无机物相羟基磷灰石(HA)的晶体结构、平均粒径及晶胞参数等的变化,结果发现:不同能量密度的激光照射后,牙本质无机物相HA颗粒的平均尺寸略微变小,但晶胞参数没有明显变化。基于XRD数据,用Popa模型的Rietveld全谱拟合得到了激光照射前后牙本质HA晶粒为长椭球形。用扫描电镜观察了激光照射后牙本质的表面形貌及微结构,发现牙本质的表面粗糙度明显增大,表面无玷污层,没有裂纹、碳化现象,未见到明显的熔融现象。本研究表明,Er,Cr∶YSGG激光消融人牙本质后无机物相没有改变,HA晶粒没有发生重结晶,牙本质表面未见到大面积熔融现象。

The purpose of this article was to estimate the effect of Er,Cr∶YSGG laser ablation on the surface crystal structure of human dentin with X-ray diffractometer(XRD).Er,Cr∶YSGG laser with different energy densities were used to ablate human dentin,and XRD was used to analyze the changes of crystal structures,average particle size,and lattice parameters of hydroxyapatite(HA)crystals before and after laser irradiation.The results show that the average size of HA particles in dentin inorganic phase decreased slightly after laser irradiation with different energy densities,but the cell parameters did not change significantly.Based on XRD data,the ellipsoidal HA grain morphology of dentin before and after laser irradiation were obtained by Rietveld full pattern fitting of Popa model.The surface morphology and microstructure of dentin after laser irradiation were observed by scanning electron microscopy.It was found that the surface roughness of dentin increased obviously,there was no stained layer on the surface,no carbonization phenomenon and crack,and no obvious melting phenomenon.This study showed that the inorganic phase did not change after Er,Cr∶YSGG laser ablation of human dentin,HA grains did not recrystallize,and large area melting was not observed on the dentin surface.