目的比较Er∶YAG激光蚀刻与传统磷酸酸蚀牙釉质表面后正畸托槽的黏接效果。方法选取因正畸需要而拔除4颗前磨牙的患者26例共104颗牙。每位患者的4颗离体前磨牙采用抽签法随机分入4组中,各组分别采用磷酸或不同工作参数的Er∶YAG激光处...目的比较Er∶YAG激光蚀刻与传统磷酸酸蚀牙釉质表面后正畸托槽的黏接效果。方法选取因正畸需要而拔除4颗前磨牙的患者26例共104颗牙。每位患者的4颗离体前磨牙采用抽签法随机分入4组中,各组分别采用磷酸或不同工作参数的Er∶YAG激光处理牙釉质表面:A组35%(质量分数)磷酸酸蚀,B组Er∶YAG激光蚀刻(能量200 m J、频率30 Hz、水量6/8),C组Er∶YAG激光蚀刻(能量250 m J、频率30 Hz、水量6/8)和D组Er∶YAG激光蚀刻(能量300 m J、频率20 Hz、水量6/8)。应用扫描电镜下观察牙釉质表面微结构变化;应用原子力显微镜观测其表面粗糙度和表面峰峰值,然后黏接托槽并进行抗剪切强度和黏接剂残余指数的测定。结果扫描电镜下观察牙釉质表面,4组都表现为釉柱中心凹陷,呈Ⅰ型酸蚀模式。C组蜂窝状边界最清晰。4组间表面粗糙度差异有统计学意义(P<0.01),其中A组最低,B、C、D 3组随激光能量值提高而增加。牙釉质表面峰峰值D组最大,A组最小。抗剪切强度A组最高,C组与A组最接近,两组间差异无统计学意义(P>0.05)。4组间的黏接剂残余指数差异无统计学意义(P>0.05)。结论在合适工作参数下,Er∶YAG激光蚀刻后,牙釉质表面形貌和黏接效能与35%(质量分数)磷酸酸蚀后效果相近。展开更多
By using oxalate group-modified TiO2 nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups（hydroxyl, hydrogen, and methyl） were used as the dispersing me...By using oxalate group-modified TiO2 nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups（hydroxyl, hydrogen, and methyl） were used as the dispersing media to prepare different electrorheological（ER） fluids. Their zero-field viscosity, yield stress under direct current electric fields, ER efficiency, shear stability, leakage current density, and sedimentation stability were tested to study the effect of carrier liquid on the properties of ER fluids. The results indicate that the zerofield viscosity, the yield stress, and the leakage current density increase with increasing viscosity of the silicone oils. The effects of the viscosity on the ER efficiency, the shear stability, and the sedimentation ratio depend on the competition between the viscous resistance and the aggregation of the particles. Among the three ER fluids prepared with silicone oil with different terminal groups, hydroxyl-terminated oil based sample has the highest zero-field viscosity, the highest field-induced yield stress and ER efficiency, the largest current density, and the best sedimentation stability.展开更多
文摘目的比较Er∶YAG激光蚀刻与传统磷酸酸蚀牙釉质表面后正畸托槽的黏接效果。方法选取因正畸需要而拔除4颗前磨牙的患者26例共104颗牙。每位患者的4颗离体前磨牙采用抽签法随机分入4组中,各组分别采用磷酸或不同工作参数的Er∶YAG激光处理牙釉质表面:A组35%(质量分数)磷酸酸蚀,B组Er∶YAG激光蚀刻(能量200 m J、频率30 Hz、水量6/8),C组Er∶YAG激光蚀刻(能量250 m J、频率30 Hz、水量6/8)和D组Er∶YAG激光蚀刻(能量300 m J、频率20 Hz、水量6/8)。应用扫描电镜下观察牙釉质表面微结构变化;应用原子力显微镜观测其表面粗糙度和表面峰峰值,然后黏接托槽并进行抗剪切强度和黏接剂残余指数的测定。结果扫描电镜下观察牙釉质表面,4组都表现为釉柱中心凹陷,呈Ⅰ型酸蚀模式。C组蜂窝状边界最清晰。4组间表面粗糙度差异有统计学意义(P<0.01),其中A组最低,B、C、D 3组随激光能量值提高而增加。牙釉质表面峰峰值D组最大,A组最小。抗剪切强度A组最高,C组与A组最接近,两组间差异无统计学意义(P>0.05)。4组间的黏接剂残余指数差异无统计学意义(P>0.05)。结论在合适工作参数下,Er∶YAG激光蚀刻后,牙釉质表面形貌和黏接效能与35%(质量分数)磷酸酸蚀后效果相近。
基金Funded by the National Natural Science Foundation of China(51478088)
文摘By using oxalate group-modified TiO2 nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups（hydroxyl, hydrogen, and methyl） were used as the dispersing media to prepare different electrorheological（ER） fluids. Their zero-field viscosity, yield stress under direct current electric fields, ER efficiency, shear stability, leakage current density, and sedimentation stability were tested to study the effect of carrier liquid on the properties of ER fluids. The results indicate that the zerofield viscosity, the yield stress, and the leakage current density increase with increasing viscosity of the silicone oils. The effects of the viscosity on the ER efficiency, the shear stability, and the sedimentation ratio depend on the competition between the viscous resistance and the aggregation of the particles. Among the three ER fluids prepared with silicone oil with different terminal groups, hydroxyl-terminated oil based sample has the highest zero-field viscosity, the highest field-induced yield stress and ER efficiency, the largest current density, and the best sedimentation stability.
