补骨脂酚的提取纯化工艺优选及其对骨质疏松症的治疗作用分析

目的:优选补骨脂酚的提取纯化工艺,并考察其对骨质疏松症的治疗作用。方法:使用乙醇回流法提取,经D101型大孔树脂纯化,通过单因素试验优选工艺条件,冷冻干燥后得到补骨脂酚;采用斑马鱼体内试验评价补骨脂酚对骨密度和骨骼发育钙化的影响。结果:优选的工艺条件为加8倍量85%乙醇浸泡过夜,回流提取3次,每次2 h,边搅拌边往补骨脂酚粗提物中加入0.2%氢氧化钠水溶液至完全溶解,过预处理好的D101型大孔树脂柱处理,上样流速1 BV·h~(-1),静置4 h,加水6 BV洗脱,用60%乙醇2 BV洗脱,加95%乙醇4 BV洗脱,收集95%乙醇的洗脱液;制备的补骨脂酚质量分数80%,收率10%。斑马鱼体内活性研究表明补骨脂酚能提高斑马鱼骨质疏松症的骨密度,且能促进正常斑马鱼骨骼发育钙化。结论:此工艺具有绿色环保、操作简便等优点,所得补骨脂酚的纯度和收率均比较理想,可开发成预防或治疗骨质疏松症的药品和食品。     

复合树脂嵌体经离体光照固化后修复牙体严重缺损的临床研究

目的：探讨一种适宜的修复牙体严重缺损的方法。方法:复合树脂嵌体经离体光固化后再黏结修复，并与其它传统修复方法比较。结果：1－1．5年临床效果显示：离体光照优于在体光照、银汞合金充填或离子充填。结论：光固化复合树脂嵌体离体固化黏结修复牙体严重缺损是一种值得临床推广的好方法。     

Biocompatibility of various root canal filling materials ex vivo

Aim  To evaluate the biocompatibility of a resin-based endodontic filler (RealSeal) using the indirect cytotoxicity test.
Methodology  Human gingival fibroblasts were cultured ex vivo . Pellets of the materials to be tested were incubated for 24, 48, and 72 h at 37 °C under sterile conditions to obtain their eluates. The fibroblasts were exposed to either diluted (50%) or undiluted eluates for 24 h. A culture medium with foetal calf serum was added to the control wells. Cell viability was estimated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide method. The data concerning cell viability were statistically analyzed using one-way anova test and Bonferroni multiple comparisons test.
Results  Eluates obtained after 24 h of incubation with the resin filler did not reduce cellular viability. An increase in cellular viability, as compared with control cells, was observed in the gutta-percha group. The undiluted eluate from the polyether material was cytotoxic, causing an 82 ± 4% decrease in cellular viability. Eluates obtained after 48 h of incubation with the resin filler increased cellular viability, whereas the polyether significantly reduced viability. Gutta-percha did not cause any detectable change. After 72 h of incubation the eluate of the resin filler caused an increase in cellular viability, as did gutta-percha, whereas polyether caused a significant decrease.
Conclusions  RealSeal resin filler was nontoxic in this laboratory model. Further investigations are necessary to verify its usefulness in clinical applications.     

The influence of 30-day-old Streptococcus mutans biofilm on the surface of esthetic restorative materials--an in vitro study

OBJECTIVE: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. METHODS: Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. RESULTS: The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. CONCLUSIONS: Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.     

氧化锆和纳米金刚石比例对核树脂挠曲强度的影响

目的 探讨二氧化锆、纳米金刚石比例对核树脂挠曲强度的影响.方法 采用双酚A-甲基丙烯酸缩水甘油酯(Bis-GMA)和二甲基丙烯酸三甘醇酯(TEGDMA)为树脂基质, 钡玻璃粉(BG)为主填料, 选择不同比例的微米或纳米级二氧化锆,纳米金刚石作为功能填料, 采用原位聚合法生成光固化牙科核树脂,万能材料试验机测定其挠曲强度.结果 含60wt%钡玻璃粉、0.2wt%纳米金刚石的树脂中,加入纳米级或微米级的二氧化锆含量分别为2wt%、3.5wt%、5wt%,3.5wt%相应核树脂挠曲强度最高;含70wt%钡玻璃粉、0.1wt%纳米金刚石的树脂中,加入40 nm的二氧化锆含量为0wt%、2wt%、3.5wt%、5wt%,2wt%质量百分比相应核树脂挠曲强度最高.结论 适当比例填料的核树脂挠曲强度能达到相应的国家标准及ISO标准的规定,能满足临床需要.     

Bonding between resin luting cement and glass infiltrated alumina-reinforced ceramics with silane coupling agent

The purpose of this study was to evaluate the shear bond strengths of three dual-cured resin luting cements (Linkmax HV, Panavia Fluoro Cement, and RelyX ARC) to glass-infiltrated alumina-reinforced ceramic material and the effect of four silane coupling agents (Clearfil Porcelain Bond, GC Ceramic Primer, Porcelain LinerM, and Tokuso Ceramic Primer) on the bond strength. The two type-shaped of In-Ceram alumina ceramic glass-infiltrated specimens were untreated or treated with one of the four ceramic primers and then cemented together with one of the three dual-cured resin luting cements. Half of the specimens were stored in water at 37 degrees C for 24 h and the other half thermocycled 20,000 times before shear bond strength testing. Surface treatment by all silane coupling agents improved the shear bond strength compared with non-treatment. The specimens treated with Clearfil Porcelain Bond showed significantly greater shear bond strength than any of the other three silane coupling agents regardless of resin luting cements and thermocycling except for the use of Panavia Fluoro Cement at 20,000 thermocycles. When the alumina-reinforced ceramic material was treated with any silane coupling agent except GC Ceramic Primer and cemented with Linkmax HV, no significant differences in bond strength were noted between after water storage and after 20,000 thermocycles. After 20,000 thermocycles, all specimens except for the combined use of Clearfil Porcelain Bond or GC Ceramic Primer and Linkmax HV and GC Ceramic Primer and Panavia Fluoro Cement showed adhesive failures at the ceramic-resin luting cement interface.     

Mechanical properties of computer-aided design/computer-aided manufacturing resin composites assuming perfect silane coupling using in silico homogenization of cryo-electron microscopy images

Purpose

The aim of this study was to determine the mechanical properties of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites for dental restoration assuming perfect silane coupling by in silico homogenization analysis using a three-dimensional model constructed from cryo-electron microscopy (cryo-EM) images.

Microstructural characterization and fracture behavior of a microhybrid and a nanofill composite

OBJECTIVES: To characterize the microstructure and composition of two different composites, and to determine their influence on the physical properties and fracture behavior. METHODS: The microstructure and composition of a microhybrid (Filtek Z250-Z2) and a nanofill (Filtek Supreme-SU) composite were analyzed using scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). Filler wt% was determined by thermogravimetric analysis. Hardness (H) and degree of conversion (DC) were evaluated at top and bottom surfaces of 2-mm thick specimens, and the dynamic elastic modulus (E) was determined with ultrasonic waves. Bar specimens (n=30) were subjected to flexure loading and flexural strength (sigmaf) was calculated (MPa). Fractographic analysis (FA) was performed to determine the fracture origin (c) for calculation of fracture toughness (KIc), and these results were compared to those from the single edge notch beam (SENB) method. Results were statistically analyzed using two-way ANOVA, Student's t-test and Weibull analysis (alpha=0.05). RESULTS: Z2 had higher filler wt%, H, E and DC at 2-mm depth as compared with SU. The fracture behavior (sigmaf and KIc) and the structural reliability (m) of the composites were similar. Results of KIc tested by SENB or calculated from fracture surfaces from flexure testing were similar. SIGNIFICANCE: The microstructural organization of the composites determines their physical properties, in spite of the similar filler content. In contrast, the microstructure did not influence the fracture behavior and the structural reliability of these highly filled composites. FA was shown to be a reliable method for determining the KIc of composites.     

Class V lesions restored with four different tooth-colored materials – 3-year results

The aim of this study was to compare the treatment results using four different types of tooth colored materials for restoring class V lesions. A total of 197 class V restorations (n = 197) were placed by one dentist in 37 patients on incisors, canines and premolars. The fillings were placed due to different indications: erosion/non-carious cervical defects (n = 69), primary carious lesions (n = 57), and for replacing defective existing fillings (n = 71). The teeth were assigned on a random basis to four groups for restoration with either a composite (group 1: n = 36; Tetric, Vivadent), or a polyacid-modified resin composite (group 2: n = 79; Dyract, Dentsply), or one of two different resin-modified glass ionomer cements (group 3: n = 51, Fuji II LC,GC; group 4: n = 31, Photac-Fil, Espe). The restorations were evaluated by a single-blind design, according to a modified USPHS system 36 months following placement. Statistical analysis was completed with the Pearson Chi-square test for comparing the results of the four groups (P < 0.05). Additionally, the survival rates were analyzed with the Kaplan-Meier estimator and the Log-rank test (P < 0.05). The Alpha ratings were as follows (Tetric/Dyract/Fuji II LC/Photac Fil): shade match (86%/77%/58%/40%), surface texture (81%/83%/16%/9%), marginal integrity (enamel) (73%/67%/61%/61%), marginal integrity (dentin) (86%/70%/55%/61%), marginal discoloration (enamel) (59%/44%/58%/52%), marginal discoloration (dentin) (82%/84%/71%/48%), anatomic contours (91%/83%/39%/35%). One Tetric restoration, five Dyract restorations, two Fuji II LC restorations and three Photac restorations were dislodged within the study period. The retention of the restorations showed no significant difference among the four materials. However, the clinical performance of the restorations retained over the 3-year period showed distinct differences for the four materials. The best clinical performance was observed for the resin composite, whereas the quality of the Dyract restorations without enamel etching was worse. The poorest results were obtained for the restorations with the resin-modified glass ionomers.     

电子探针观察氧化锆与树脂黏接断面的研究

目的　观察经二氧化硅(silica ,SiO2 )表面处理的摩尔分数为3%的氧化钇稳定的四方多晶氧化锆(3Y -TZP)与树脂黏接后的断面,了解SiO2 表面处理在3Y -TZP与牙科树脂黏接中的作用。方法　用溶胶-凝胶法在4个3Y -TZP试样上制备SiO2 薄膜作为薄膜组;另外4个3Y -TZP试样作为对照组。分别用EPMA 870 5QH2 电子探针和INCAEnergy能谱仪观察两组试样在拉伸剪切试验后的黏接断面。结果　背散射电子形貌像显示两组的3Y -TZP基底面均未破坏,但薄膜组表面残留的树脂黏接剂颗粒较多。电子探针能谱分析显示薄膜组在3Y -TZP表面存在比对照组高的硅峰谱。结论　经SiO2 表面处理后的3Y-TZP可提高与牙科树脂的黏接力。