【作者】 陈雪；

【导师】 朱松；

【作者基本信息】 吉林大学 ， 口腔医学硕士（专业学位）， 2024， 硕士

【摘要】 目的:本研究的目的是在模拟髓腔压力下,评估Er:YAG激光预处理牙本质的即刻和老化微拉伸粘接强度以及界面纳米渗漏的改变,分析粘接界面超微结构以及牙本质化学成分的变化。方法:收集112颗新鲜拔除完整无龋坏的离体第三磨牙,浸泡在0.5%的氯胺T溶液中,保存不超过3个月。平行于(牙合)平面和釉牙骨质界切除牙釉质及牙根,粘接于髓腔压力模型24 h后,根据不同处理方式分为五组:对照组(n=26),激光60 m J(n=20),80 m J(n=20),100 m J(n=26),120 m J(n=20)。使用通用型粘接剂的自酸蚀模式(Single Bond Universal)将树脂粘接在牙本质表面。每组随机分为两个亚组,分别采用去离子水保存24 h和冷热循环老化10000次处理。将每组样本制备呈横截面积为1 mm~2的条状试件,进行微拉伸粘接强度(μTBS)、断裂模式、纳米渗漏检测。采用扫描电子显微镜(SEM)、衰减全反射傅里叶变换红外光谱(ATR-FTIR)、X射线衍射(XRD)以及能量色散X射线光谱仪(EDX)等方法对各组样本进行分析。μTBS结果采用双因素方差分析,EDX结果采用独立样本t检验,采用Tukey’s后置多重比较检验进行组间多重比较分析,并将显著性水平定为0.05。结果:1.双因素方差分析显示,微拉伸粘接强度受激光参数(p<0.001,F=14.454)和老化(p<0.001,F=30.740)的影响,但能量水平和老化没有交互作用(p=0.823,F=0.380)。激光组的微拉伸粘接强度显著高于对照组(p<0.05),且能量为100 m J激光组中观察到最高值,但60、80、120 m J组之间的μTBS都无显著差异(p>0.05)。老化后,对照组牙本质粘接强度显著降低(p<0.05),60、80 m J组粘接强度保持稳定(p>0.05),100、120 m J组粘接强度明显低于即刻组(p<0.05)。老化前后,各组的断裂模式主要是界面断裂,牙本质内聚断裂占比最少。2.纳米渗漏结果显示,对照组中银颗粒在混合层底部呈连续的条带状沉积,而激光组则观察到不连续带状银沉积物。冷热循环老化后,混合层底部银沉积物增加,且部分牙本质小管内、粘接层内也可见银沉积物。3.扫描电镜结果显示,对照组牙本质表面可见均匀的玷污层,未见牙本质小管口;激光照射后牙本质表面粗糙呈鳞状,牙本质小管开放,无玷污层,没有出现熔融碳化区域。对照组形成的混合层薄且树脂突少且短小,激光组混合层更厚且均匀,树脂突多且粗长,并可观察到横向分支;老化后各组粘接界面的混合层和树脂突与即刻组相似。4.EDX结果显示激光处理前后牙本质钙、磷重量比差异不显著(p>0.05),但钙磷比值显著增加(p<0.05)。5.FTIR和XRD显示有机和无机物峰强度有所降低,但各峰的位置和形态以及牙本质晶相结构没有改变。结论:模拟牙髓压力下,Er:YAG激光处理后牙本质呈粗糙不规则表面,可见开放的牙本质小管口,无玷污层,增加了牙本质粘接面积且利于粘接剂渗入牙本质,形成高质量混合层和树脂突,从而提高牙本质的粘接强度,当能量为100 mJ时效果最佳。更多还原

【Abstract】 Objectives:To evaluate the immediate and aged micro-tensile bond strength（μTBS）and interfacial nanoleakage of the dentin following erbium:yttrium aluminum garnet（Er:YAG）laser treatment under simulated pulpal pressure.To analyze bond interface ultramorphological characteristics and dentin chemical composition modifications.Methods:In this investigation,112 sound human molars were employed.They were kept in 0.5%chloramine T for maximum of three months.To remove the enamel and root,specimens were sectioned parallel to the occlusal plane and the cemento-enamel junction.And after being subjected to a simulated pulpal pressure of 15 cm H₂O for 24 hours,they were then randomly divided into five groups based on different treatments:the laser group received Er:YAG laser treatment at settings of 60 m J/10 Hz,80 m J/10 Hz,100 m J/10 Hz,and 120 m J/10 Hz,respectively,while the control group only had their dentin surfaces ground with 600 Si C paper.Following that,100specimens were repaired using a resin composite and universal adhesive system in self-etch mode（SBU）,and divided into two subgroups:24-hour distilled water storage and thermocycling test.The specimens were subsequently sectioned in beams with a cross-sectional area of 1 mm²,and micro-tensile bond strength（μTBS）,failure modes,and nanoleakage were evaluated.The samples were analyzed adopting methods such as SEM-EDX atomic analysis,attenuated total reflection Fourier transform infrared spectroscopy（FTIR）,and X-ray diffraction（XRD）.TheμTBS results were analyzed by two-way ANOVA,the EDX results were analyzed by independent samples t-test,and multiple comparisons between groups were analyzed by Tukey’s post hoc multiple comparison test,and the significance level was set at 0.05.Results:1.Two-way ANOVA showed thatμTBS was affected by laser parameters（p<0.001,F=14.454）and aging（p<0.001,F=30.740）,but there was no interaction between energy and aging（p=0.823,F=0.380）.TheμTBS after laser treatment was significantly higher than that of the control group（p<0.05）,and the highestμTBS was observed in the group with an energy of 100m J laser.However,no significant differences inμTBS were observed between the 60,80,and 120m J groups in both the immediate and aging groups（p>0.05）.The aging analysis results showed a significant decrease in bond strength in the control group after aging（p<0.05）,while the bond strengths of 60,80 m J groups remained stable（p>0.05）.The bond strengths of 100,120 m J groups were significantly lower than those of the immediate group（p<0.05）.Adhesive failure,whether immediate or aging,accounted for the majority of fracture modes in each group,and cohesive failure within the dentin was the least prevalent in all groups.2.In the control group,immediate nanoleakage showed continuous band-like silver deposition at the bottom of the hybrid layer.In contrast,discontinuous bands of silver deposits were observed at the bottom of the hybrid layer in the laser treatment group.After aging,the silver particle deposits increased with silver deposits visible within some tubules and adhesive layer.3.The SEM analysis showed a homogeneous smear layer with occluded dentinal tubules on the dentin surface in the control group.By contrast,the lased dentin surface showed a scaly structure without a smear layer accompanied by a clearly exposed dentinal tubule orifice.Compared to the control group,the hybrid layer in the 100 m J group was thicker and more uniform,with a greater number of resin tags,and transverse branches were observed on the resin tags.The hybrid layer and resin tags at the interfaces of the groups after aging were similar to those of the immediate ones,and cracks were visible at the interfaces.4.EDX results showed that the difference between the calcium and phosphorus weight ratios of dentin before and after laser treatment was not significant（p>0.05）,but the calcium-phosphorus ratio increased significantly（p<0.05）.5.FTIR and XRD showed a decrease in the intensity of the organic and inorganic peaks,but the position and morphology of the peaks and the crystalline phase structure of dentin remained unchanged.Conclusions:Under simulated pulp pressure,the surface of dentin after Er:YAG laser irradiation was rough and irregular,and exposed dentin tubules with no smear layer,which increased the bonding area of dentin and facilitated the penetration of the adhesive into dentin,forming a superior hybrid layer and resin tags,thus improving the adhesive strength of dentin.The optimal bond strength was achieved at 100 mJ.更多还原