Influence of surface properties of resin‐based composites on in vitro Streptococcus mutans biofilm development

The aim of this in vitro study was to evaluate the influence of physicochemical surface properties of resin‐based composites on Streptococcus mutans biofilm formation. Specimens were prepared from each of four resin‐based composites by polymerization against Mylar strips. Half of the number of specimens received no further surface treatment, whereas the other half were subjected to a polishing treatment. Surface roughness (SR) and topography were assessed using profilometry and atomic force microscopy. Surface free‐energy (SFE) was determined, and the chemical surface composition was analysed by X‐ray photoelectron spectroscopy (XPS). S. mutans biofilms were formed on the surface of the resin‐based composite specimens for either 48 or 96 h using an artificial mouth system (AMS). Polishing caused a significant decrease in SFE, and XPS analysis indicated an increase of surface silicon and a decrease of surface carbon. Only for Grandio was a significant increase in SR identified after polishing, which was probably related to the higher concentration of filler particles on its surface. Significantly less S. mutans biofilm formation was observed on polished resin‐based composites than on unpolished resin‐based composites. These results indicate that the proportions of resin matrix and filler particles on the surface of resin‐based composites strongly influence S. mutans biofilm formation in vitro, suggesting that minimization of resin matrix exposure might be useful to reduce biofilm formation on the surface of resin‐based composites.     

Resin infiltration of deproteinised natural occlusal subsurface lesions improves initial quality of fissure sealing

The aim of this ex vivo study was to evaluate the infiltration capability and rate of microleakage of a low-viscous resin infiltrant combined with a flowable composite resin (RI/CR) when used with deproteinised and etched occlusal subsurface lesions (International Caries Detection and Assessment System code 2). This combined treatment procedure was compared with the exclusive use of flowable composite resin (CR) for fissure sealing. Twenty premolars and 20 molars revealing non-cavitated occlusal carious lesions were randomly divided into two groups and were meticulously cleaned and deproteinised using NaOCl (2%). After etching with HCl (15%), 10 premolar and 10 molar lesions were infiltrated (Icon/DMG; rhodamine B isothiocyanate (RITC)-labelled) followed by fissure sealing (G-?nial Flo/GC; experimental group, RI/CR). In the control group (CR), the carious fissures were only sealed. Specimens were cut perpendicular to the occlusal surface and through the area of the highest demineralisation (DIAGNOdent pen, KaVo). Using confocal laser-scanning microscopy, the specimens were assessed with regard to the percentage of caries infiltration, marginal adaption and internal integrity. Within the CR group, the carious lesions were not infiltrated. Both premolar (57.9%± 23.1%) and molar lesions (35.3%± 22.1%) of the RI/CR group were uniformly infiltrated to a substantial extent, albeit with significant differences (P=0.034). Moreover, microleakage (n=1) and the occurrence of voids (n=2) were reduced in the RI/CR group compared with the CR group (5 and 17 specimens, respectively). The RI/CR approach increases the initial quality of fissure sealing and is recommended for the clinical control of occlusal caries.     

In vitro degradation of resin–dentin bonds with one-bottle self-etching adhesives

The purpose of this study was to evaluate the durability of one-bottle self-etching adhesive during long-term water-storage testing. Resin–dentin bonded specimens were prepared using four commercially available one-bottle self-etching adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beam-shaped specimens that were stored in water for 24 h (control group) and 100, 200, and 300 d (experimental groups). After each storage period, the beams were subjected to a microtensile bond test. After the bond test, fractured surfaces were examined using a scanning electron microscope. In addition, interfacial observations of the silver tracer were performed using the secondary and back-scatter modes of the scanning electron microscope. The bond strength of all tested adhesives decreased significantly after 100 or more days in water. The interfacial observations showed an oxygen-inhibition zone as electron lucent in the adhesive–composite border in control specimens, displaying silver impregnation with breakage after aging. The deterioration of the oxygen-inhibition zone in the adhesive–resin composite junction resulted in a decrease in bond strength after 100 d in water for one-bottle self-etching adhesives.     

多模微波辅助的聚乙二醇化聚苯乙烯树脂制备

目的：研究一种微波辅助的聚苯乙烯树脂聚乙二醇（PEG）化的方法。方法使用PEG 200对市售Merrifield树脂进行修饰,尝试了不同条件下PEG化的效率。使用自行制备的PEG化树脂进一步衍生化,并进行氨基酸的负载,与市售王树脂进行比对。结果优选出了一套较为合适的反应参数,使用5 g树脂,50 ml PEG 200,微波功率600 W,预设温度170℃,照射15 min,共2次,获得了接近90%的负载率。衍生化得到PEG化王树脂后与氨基酸进行缩合,获得了令人满意的产率。结论本文首次报道了多模微波装置辅助的聚苯乙烯树脂PEG化,该方法操作简单,制备快速,条件温和,产率满意,远远优于传统制备方法。     

不同型号大孔吸附树脂对莱菔子水提液中萝卜苷的吸附性考察

目的:研究不同型号大孔吸附树脂对莱菔子水提液中萝卜苷的纯化效果,筛选适合萝卜苷纯化的最佳型号树脂。方法:以萝卜苷的纯化效率为指标,采用高效液相色谱法测定莱菔子水提液和洗脱液中萝卜苷的含量,选择最佳型号大孔树脂。结果:X-5型大孔吸附树脂对萝卜苷的纯化率为86.2%,表明X-5型树脂更适合莱菔子中萝卜苷的纯化。萝卜苷在X-5型树脂上的吸附平衡时间为4 h。结论:采用X-5型大孔吸附树脂纯化莱菔子中萝卜苷是可行的。     

Er:YAG 激光和酸蚀预处理对自粘结树脂水门汀粘结强度的影响

目的:探讨Er:YAG 激光和酸蚀预处理对自粘结树脂水门汀粘结强度的影响?方法:44颗前磨牙根据对牙本质表面预处理方式的不同随机分为4组:对照组?Er:YAG 激光组?酸蚀组(35%磷酸)?Er:YAG 激光+酸蚀组?每组11颗牙中随机选出1颗切取3 mm厚牙本质片,按相应分组要求预处理后进行扫描电镜观察;每组剩余10颗牙制备一致标准牙本质表面后按相应分组要求预处理,用自粘结树脂水门汀RelyXTM Unicem将其与Everest ZS 氧化锆瓷片粘结,24 h后测试各组剪切粘结强度并进行统计分析?结果:扫描电镜观察显示采用不同方式预处理后,牙本质表面形态改变明显;统计分析结果显示剪切粘结强度由高到低为Er:YAG 激光组(7.18 ± 2.54)MPa?Er:YAG 激光+酸蚀组(5.50 ± 2.09)MPa?对照组(4.05 ± 1.04)MPa?酸蚀组(3.61 ± 0.70)MPa;Er:YAG 激光组?Er:YAG 激光+酸蚀组与对照组有显著性差异(P < 0.05),酸蚀组与对照组无显著性差异(P > 0.05)?结论:酸蚀对自粘结树脂粘结强度的改变无明显影响,Er:YAG 激光预处理能有效提高自粘结树脂与牙本质和氧化锆瓷的粘结强度?     

石菖蒲大孔树脂不同洗脱部位高效液相图谱与抗抑郁效应的关联性研究

目的：研究石菖蒲大孔树脂不同洗脱部位高效液相图谱与抗抑郁效应的关联性。方法采用AB‐8大孔树脂制备石菖蒲不同部位。采用梯度洗脱法建立石菖蒲原药材及不同树脂洗脱部位的高效液相特征图谱,并确认图谱中特征峰及对应特征峰之间的峰面积数据关系。运用小鼠悬尾实验（TST）、游泳实验（FST）等小鼠行为学实验,观察口服石菖蒲及不同树脂洗脱部位抗抑郁效应。结果石菖蒲原药材及不同AB‐8树脂洗脱部位的特征图谱具有特征共有峰。石菖蒲大孔树脂90％及70％乙醇洗脱部分能显著缩短TST和FST。石菖蒲抗抑郁效应与特征峰具有关联性。结论石菖蒲具有抗抑郁作用,其主要抗抑郁效应来源于AB‐8树脂70％及90％乙醇洗脱部位。石菖蒲液相特征图谱及相关峰数据关系可用于衡量石菖蒲的抗抑郁效应,为今后石菖蒲用于抗抑郁效应研究及开发提供依据。     

三官能团环氧树脂常温固化剂的复配研究及其固化动力学

以间苯二酚二缩水甘油醚(RDGE)和1,1,1-三(对羟基苯基)乙烷为原料,合成了三官能团环氧树脂TEP,并分别与异佛尔酮二胺(IPDA)单一体系和IPDA/2-乙基-4-甲基咪唑(2E4MZ)复合体系进行常温固化。通过DSC、热重分析(TGA)、动态机械热分析仪、耐化学介质以及力学性能测试对比研究了TEP树脂与两种固化体系的固化反应动力学、固化度以及热稳定性。结果表明:复合固化体系较单一固化体系初始表观活化能更低,复合体系固化物的固化程度、玻璃化转变温度、耐腐蚀性均优于单一IPDA固化体系。     

大孔吸附树脂分离纯化淫羊藿EF5黄酮

目的：采用HPLC法和UV法监测AB-8大孔吸附树脂分离纯化以淫羊藿苷、朝藿定A、朝藿定B、朝藿定C和宝藿苷I这五种黄酮为主要成分的淫羊藿EF5黄酮并筛选出最佳分离纯化工艺参数。方法：采用UV法,以淫羊藿总黄酮洗脱率为指标,考察树脂对淫羊藿总黄酮的吸附容量、解吸附率、吸附动力学,以确定树脂分离纯化淫羊藿EF5黄酮的最佳吸附性能;采用HPLC法,以淫羊藿EF5黄酮中五种黄酮单体的洗脱率为指标,考察洗脱液浓度和洗脱液用量等参数,确定淫羊藿EF5黄酮的最佳洗脱参数。结果：AB-8大孔吸附树脂对淫羊藿总黄酮的吸附容量以湿树脂计为（58.37±2.36）mg·g-1,解吸附率为（86.77±2.32）%,最佳吸附时间为180min,最佳洗脱液为60%乙醇,最佳洗脱液用量为5BV,纯化后真空干燥所得棕褐色淫羊藿EF5黄酮粉末中朝藿定A、朝藿定B、朝藿定C、淫羊藿苷和宝藿苷I的含量分别为3.51%、4.87%、1.22%、33.05%、1.36%,淫羊藿EF5黄酮纯度为44%。结论：AB-8大孔吸附树脂分离纯化得到的淫羊藿EF5黄酮的纯度较高,适合工业生产。