Evaluation of the effectiveness of bioactive glass fillers against Candida albicans adhesion to PMMA denture base materials: An in vitro study

BackgroundDentures with antimicrobial properties are desirable for preventing Candida albicans adhesion. This study was to assess the effectiveness of bioactive glass (BAG) on C. albicans adhesion, surface roughness, and hardness of denture base materials.MethodsHeat-polymerized (HP) and autopolymerized (AP) acrylic resins were used to fabricate 240 disk specimens (120/material, 60/C. albicans, 60/surface roughness and hardness). Specimens were divided into five groups (n = 10) based on the BAG concentration: 0.5, 1.5, 3, 5, and 7.5 wt% of the acrylic powder, with a control group comprised of unmodified specimens. Direct culture method was used to assess C. albicans adhesion. A profilometer and Vickers hardness test were used to measure surface roughness and hardness respectively. Analysis of variance (ANOVA) and post hoc Tukey’s test were used for data analysis (α = 0.05).ResultsBAG addition significantly decreased the C. albicans count when compared with the control group (P < 0.001) for both HP and AP. Regarding surface roughness, there was no change in the HP acrylic resins (P > 0.05), while the AP acrylic resins exhibited significantly higher surface roughness with BAG addition (P < 0.001). The hardness of the HP and AP acrylic resins were significantly higher with the addition of BAG (P < 0.001).ConclusionsThe addition of BAG to HP and AP acrylic resins effectively decreases C. albicans adhesion. The roughness of AP acrylic resins increases with the addition of BAG, while the hardness of both HP and AP acrylic resins increase with the addition of BAG.     

不同表面处理对LAVA树脂纳米瓷剪切强度的影响

目的 研究不同处理方式对树脂纳米瓷(LAVA Ultimate)与树脂水门汀粘接后剪切强度的影响。方法 本次实验分为喷砂实验和粘接实验两部分。将LAVA Ultimate切削成大小约 6 mm×6 mm,高度约为2 mm的样本80片,依照不同的喷砂时间和喷砂气压随机分为4组,每组10个试件,使用3M Single Bond Universal+3M RelyX Ultimate与纳米树脂柱粘接后在万能试验机上测试断裂载荷,计算剪切强度,选出最高组。同等喷砂条件下40个样本随机分为A(Single Bond Universal(3M)+RelyX Ultimate(3M)) ,B (Porcelain Primer(Bisco)+ All-bond Universal(Bisco)+RelyX Ultimate(3M))与纳米树脂柱进行粘接。粘接后再分成两个亚组,分别进行冷热循环5 000次和恒温水浴24 h。在万能试验机上测试断裂载荷,计算剪切强度,采用单因素方差分析对数据进行统计分析。结果 单因素方差分析结果表明不同喷砂条件的分组对剪切强度差异有统计学意义(第2组和第4组)(P=0.037);冷热循环后,A组和B组试件的剪切强度均有明显下降(P=0.003,P<0.01);A、B组不同粘接方式的剪切强度差异无统计学意义(P=0.062,P=0.671)。结论 0.2 MPa压力下喷砂14 s可明显提高树脂纳米瓷与树脂水门汀的剪切强度;冷热循环会明显降低剪切强度;粘接方式对剪切强度无明显影响。     

Evaluation of a Fluorescence-aided Identification Technique (FIT) to assist clean-up after orthodontic bracket debonding

Objectives:To compare a fluorescence-aided identification technique (FIT) with a conventional light source (CLS) for removing composite during debonding of brackets with respect to time needed, composite remnants, and tooth substance loss.Materials and Methods:Twelve maxillary models with 10 bovine teeth each were digitally surface-scanned and metal brackets were bonded on each tooth with Opal Seal and Opal Bond. Two operators: an experienced orthodontist (A) and an undergraduate student (B) received six models each and were asked to remove the composite remnants with a tungsten carbide bur and Sof-Lex discs by both a conventional light source (CLS group, n = 3), and fluorescent inducing light (FIT group, n = 3). The time taken was recorded, and a postoperative scan was digitally superimposed on the preoperative scan to quantify number of teeth with composite remnants and volume and thickness of enamel loss and composite remnants. Chi-square test and independent t-tests were performed to compare methods with a significance level of 5%.Results:Compared to CLS, both operators needed significantly less time when using the FIT method and degree of enamel loss, height, and volume of composite remnants and total remaining composite remnants were significantly reduced. By FIT, the volume of enamel loss was significantly reduced for operator A only. Operator B removed the same enamel volume with either method.Conclusions:Cleanup after orthodontic debonding with the FIT was superior regarding time needed and removal of composite remnants. Total enamel loss reduction was operator-dependent.     

Copper scavenging efficiency of adsorbents prepared from Raphia hookeri fruit waste

Low cost adsorbents prepared from the epicarp of Raphia hookeri fruit were used for the removal of copper (II) ion from aqueous solution. The effects of operational parameters such as pH, concentration and contact time, dosage as well as interference of other ions were studied. Optimum pH for raw and modified biomass were 5.0 and 5.5 with percentage removal of 75.08% and 95.62% respectively. Concentration of competing ions greatly reduced Cu²⁺ removal with both adsorbents while agitation speed had negligible effect on Cu²⁺ uptake. Adsorbents surfaces were activated as temperature increased thus enhancing adsorbent adsorption capacity at high temperature. Adsorption kinetic data fitted best into the pseudo second order model while the thermodynamics studies confirmed adsorption spontaneity and feasibility. The Freundlich adsorption isotherm best described the adsorption process and the Langmuir maximum monolayer adsorption capacity for the raw (RHE) and acid treated (ARHE) biomass were 81.97 and 103.09 mg/g respectively. Chemisorption predominate the Cu²⁺-ARHE system hence desorption efficiency was obtained to be 72.65% with CH₃COOH as eluent.     

Study on Adsorption Properties of Calcined Mg–Al Hydrotalcite for Sulfate Ion and Chloride Ion in Cement Paste

In the marine environment, sulfate ions and chloride ions are abundant. Therefore, sulfate attack and chloride ion attack are common failure forms of marine concrete. Mg–Al hydrotalcite is a layered bimetallic hydroxide, which can be used as guest molecular adsorbent. In this experiment, we synthesized Mg–Al hydrotalcite, and the crystal state, surface morphology, and composition of this adsorbent were investigated by modern micro-analysis technology. Mg–Al hydrotalcite was added into the prepared target ion solution, to explore the influence of various factors on the adsorption performance of Mg–Al hydrotalcite, and then calcined Mg–Al hydrotalcite was added into cement paste, to study the mechanical properties and durability of the paste samples. The experimental results show that the optimum conditions for adsorption of chloride ions by calcined Mg–Al hydrotalcite are an adsorption time of 4 h, temperature of 35 °C, LDO (calcined Mg-Al hydrotalcite) dosage of 3.5 g/L, and a pH of 8. The adsorption effect of sulfate ion is best when the adsorption time is 6 h, the temperature is 35 °C, the dosage of LDO is 4 g/L, and the pH = 8. The optimal adsorption conditions of calcined Mg–Al hydrotalcite for chloride ion and sulfate ion are not completely the same, and the adsorption of these two ions in mixed solution shows competitive adsorption. Compared with the common paste specimens without Mg–Al hydrotalcite, the mechanical properties and deformation properties of cement specimens can be significantly improved by adding Mg–Al hydrotalcite.     

Preparation of Zn doped mesoporous silica nanoparticles (Zn-MSNs) for the improvement of mechanical and antibacterial properties of dental resin composites

ObjectiveThe purpose of this work was to explore the enhancement effect of zinc doped mesoporous silica nanoparticles (Zn-MSNs), which could form micromechanical interlocking with resin matrix and sustainably release Zn²⁺, on the mechanical and antibacterial properties of the dental resin composites.MethodsZn-MSNs were prepared by a sol–gel method, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N₂ adsorption/desorption. The mechanical properties of the dental composites reinforced by Zn-MSNs were measured by a universal mechanical testing machine. Antibacterial activities of dental composites were evaluated by both qualitative and quantitative analysis using Streptococcus mutans (S. mutans). The cytotoxicity of the Zn-MSNs filled dental composites was investigated by osteoblasts (OBs).ResultsThe synthesized Zn-MSNs possessed good monodispersity with an average particle size of about 138 nm. The mechanical properties of the composites gradually increased with the increase of the content of Zn-MSNs. The flexural strength, flexural modulus, compressive strength and micro-hardness of the composites containing 15 wt% Zn-MSNs were 31.21%, 50.47%, 53.83% and 26.79% higher than the samples with no Zn-MSNs, respectively. The antibacterial performance was significantly improved by the addition of Zn-MSNs and the antibacterial rate of the composite with 15 wt% of Zn-MSNs reached 100%. Cytotoxicity tests revealed that all the composites were biocompatible during OBs incubation.SignificanceThe prepared Zn-MSNs can effectively improve the mechanical and antibacterial properties of the dental resin composites.     

水中邻苯二甲酸酯吸附材料的研究进展

邻苯二甲酸酯(PAEs)被广泛应用于食品包装、玩具和医疗产品,以改善其塑性和弹性。PAEs易于向水体中迁移,并因其具有内分泌干扰特性而成为目前最受公众关注的污染物之一。笔者总结了目前吸附法处理PAEs的最新研究和发展趋势,重点综述了各类吸附材料如活性炭、壳聚糖、人工合成树脂、粘土矿物材料对PAEs的吸附效能和机制,并在此基础上对吸附法处理PAEs的发展方向进行展望。     

Methods of reducing the level of indoxyl sulfate – one of the most potent protein-bound uremic toxins

Chronic kidney disease (CKD) is associated with accumulation of uremic toxins, especially indoxyl sulfate (IS). IS has multi-directional, adverse influence on the organism, and is connected with cardiovascular and bone diseases. These properties make reducing level of IS so important issue. This article reviews methods allowing to reduce concentration of IS. Authors present methods like dialysis, using albumin-binding competitors, trans-cellular transporters and adsorbents, facilitation of dissociation from albumin, as well as modification of diet and intestinal bacteria. Despite the continued improvement and invention of new strategies, development of effective and safety methods of IS removing is still a challenge for researchers.     

高纯度庆大霉素C1a游离碱制备工艺研究

目的 探索用大孔吸附树脂层析法及盐析结晶法精制纯化硫酸依替米星起始物料-庆大霉素C1a成品(HPLC纯度91%~93%)，从而减少由起始物料引入依替米星杂质的水平。方法 以庆大霉素C1a吸附量和庆大霉素C1a纯度为指标，考察大孔吸附树脂纯化庆大霉素C1a的吸附性能和洗脱参数；以盐析后庆大霉素C1a样品纯度和盐析收率为指标，考察盐析工艺最佳温度、溶剂、酸的添加量及酸的种类。结果 获得较优的树脂NM200，获得较优的解析液pH值为2.0和流速0.5BV/h。经过优化后，纯化收率从65%提高至74%。通过盐析结晶条件筛选和优化，确定室温先加溶剂后加硫酸(pH6.5)和甲醇与乙醇1:2的条件较优，优化后获得的庆大霉素C1a纯度达到98.2%，收率大于93%。研究了多种无机酸盐析结晶的情况，发现磷酸、硫酸和碳酸条件下能析出白色固体。结论 通过比较大孔吸附树脂和盐析结晶的纯化连接，组合纯化后获得的庆大霉素C1a游离碱纯度大于99.0%，比纯化前样品提高6%以上，收率大于70%。