超短脉冲Er:YAG激光对提高牙本质粘结强度最佳脉冲宽度的研究

Study on optimal pulse width of ultra-short pulseEr:YAG laser for improving dentin adhesion

目的探究超短脉冲Er:YAG激光对提高牙本质粘结强度的最佳脉冲宽度。方法选取50颗离体的第三磨牙在颈部按楔状缺损形态制备,取冠向面,将样本随机分为5组,G0组为空白对照组,G1~G4组,使用30 MJ,20 Hz Er:YAG激光处理,脉冲宽度分别设置为30、40、50、60μs。扫描电子显微镜(SEM)观察各组牙本质表面的形态学改变,并通过能量色散X射线光谱(EDX)检测各组钙磷比。通过冷热循环实验,以万能力学试验机测试各组剪切粘结强度(SBS)及体式显微镜下的断裂形式。评价不同脉宽值对提高牙本质粘结强度的影响。结果SEM观察牙本质表面经不同脉冲宽度激光处理后玷污层均去除,牙本质小管有不同程度的开放,经激光处理后牙本质表面钙磷比均上升,G2组激光处理前后的钙磷比值变化差异有统计学意义(P<0.05)。冷热循环实验后SBS平均值:G2>G3>G1>G4>G0,G2组与G0组、G1组、G3组和G4组组间差异有统计学意义(P<0.05);G0组与G1组、G2组、G3组和G4组组间差异有统计学意义(P<0.05)。各组断裂形式主要为类型1和类型3。结论30 MJ,20 Hz Er:YAG激光脉冲宽度设置为40μs可显著提高牙本质的粘结强度。

Objective To explore the optimal pulse width of ultra-short pulse Er:YAG laser for improving dentin bonding strength.Methods Forty isolated third molars were prepared in the shape of wedge defect in the neck,and the coronal plane was taken.The samples were randomly divided into 5 groups:group G0 was blank group,and groups G1-G4 were treated with 30 MJ,20 Hz Er:YAG laser,and the pulse width was set to 30,40,50 and 60μs,respectively.The morphology of dentin surface was observed by scanning electron microscopy(SEM),and the ratio of calcium to phosphorus was detected by energy dispersive X-ray spectroscopy(EDX).The shear bond strength(SBS)of each group and the fracture form under the type microscope were tested by the universal mechanical testing machine.The effect of different pulse width on improving dentin bonding strength was evaluated.Results SEM observation showed that the stained layer was removed after laser treatment with different pulse widths,and the dentin tubules were opened to different degrees.The calcium-phosphorus ratio of dentin after laser treatment increased,and the difference of calcium-phosphorus ratio in G2 group was statistically significant(P<0.05).The mean value of SBS after the cold and hot cycle experiment was G2>G3>G1>G4>G0,and the difference between G2 group and G0 group,G1 group,G3 group and G4 group are statistically significant(P<0.05).The difference between group G0 and groups G1,G2,G3 and G4 was statistically significant(P<0.05).The main fracture forms of each group were type 1 and type 3.Conclusion The 30 MJ,20 Hz Er:YAG laser pulse width of 40μs can significantly improve the bond strength of dentin.