An evaluation of microleakage of various glass ionomer based restorative materials in deciduous and permanent teeth: An in vitro study

AimTo evaluate the microleakage of recently available glass ionomer based restorative materials (GC Fuji IX GP, GC Fuji VII, and Dyract) and compare their microleakage with the previously existing glass ionomer restorative materials (GC Fuji II LC) in primary and permanent teeth.MethodOne hundred and fifty (75 + 75) non-carious deciduous and permanent teeth were restored with glass ionomer based restorative materials after making class I cavities. Samples were subjected to thermocycling after storing in distilled water for 24 h. Two coats of nail polish were applied 1 mm short of restorative margins and samples sectioned buccolingually after storing in methylene blue dye for 24 h. Microleakage was assessed using stereomicroscope.ResultSignificant differences (P < 0.05) were found when inter group comparisons were done. Except when GC Fuji VII (Group III) was compared with GC Fuji II LC (Group II) and Dyract (Group IV), non-significant differences (P > 0.05) were observed. It was found that there was no statistically significant difference when the means of microleakage of primary teeth were compared with those of permanent teeth.ConclusionsGC Fuji IX GP showed maximum microleakage and GC Fuji VII showed least microleakage.     

Chitin-based poly(urea-urethane)s

—Chitins of various origins in DMA-LiCl solution have been reacted with excess 1,6-diisocyanatohexane (three or twelve equivalents per repeating unit) for 4-20 h. The resulting solutions were exposed to water vapor for 2 days and flexible and opaque materials were produced, which upon drying yielded powders whose main characteristics were insolubility in aqueous and organic solvents, remarkable crystallinity, typical infrared spectrum, high N/C ratio (0.287), and a high degree of substitution (0.29). Under the SEM structural features reminiscent of chitin were absent but no thermoplastic behavior was found by differential scanning calorimetry. Chitosan was similarly treated under heterogeneous conditions in anhydrous pyridine, and yielded reaction products with a lower degree of substitution (0.17). With partially hydrolysed chitosan, highly crystalline products were obtained.     

Fluoride bioactive glass paste improves bond durability and remineralizes tooth structure prior to adhesive restoration

ObjectiveThe current study aimed at examining a fluoride containing bioactive glass (BiominF®) paste as a temporary filling material capable of remineralizing the demineralized enamel or dentin, and its ability to decrease a simulated dentinal fluids pressure on the resin/dentin interface, without affecting the shear bond strength of a universal bonding agent to enamel and dentin.Methods60 premolars were utilized for the acid resistance, trans-microradiography (TMR) and shear bond strength (SBS) experiments. Enamel and dentin discs were demineralized for 4 days to create a subsurface demineralized zone followed by applying BiominF® paste, 1.23% acidulated phosphate fluoride, or a temporary filling material for 24 h.30 extracted human non-carious third molars were utilized for the pulpal pressure experiment in which direct communication to the pulp chamber was created by cutting at a level approximately 1 mm below the cemento-enamel junction while the coronal enamel was ground to expose mid coronal dentin. The dentin surface was exposed to a simulated pulpal pressure. The dentin surfaces had BiominF® paste, an oxalate desensitizing agent, or temporary filling material followed by application of a universal adhesive system.ResultsOne way ANOVA showed that BiominF® paste remineralized effectively the demineralized enamel or dentin, did not affect the bond strength of the enamel and dentin surfaces to the tested adhesive system p < 0.05, and improved the acid resistance of the demineralized enamel and dentin against a secondary erosive challenge. Moreover, BiominF® paste decreased the nanoleakage expression in the dentin/adhesive interface exposed to a simulated pulpal pressure.SignificanceBiominF® paste may serve as a temporary filling material that may improve the longevity of adhesive restorations and help to conserve tooth structures by preserving the demineralized enamel and dentin form cutting during cavity preparation.     

Counting primary loops in polymer gels

Much of our fundamental knowledge related to polymer networks is built on an assumption of ideal end-linked network structure. Real networks invariably possess topological imperfections that negatively affect mechanical properties; modifications of classical network theories have been developed to account for these defects. Despite decades of effort, there are no known experimental protocols for precise quantification of even the simplest topological network imperfections: primary loops. Here we present a simple conceptual framework that enables primary loop quantification in polymeric materials. We apply this framework to measure the fraction of primary loop junctions in trifunctional PEG-based hydrogels. We anticipate that the concepts described here will open new avenues of theoretical and experimental research related to polymer network structure.     

肿瘤相关性贫血的治疗

肿瘤相关性贫血是肿瘤相关性炎症或肿瘤相关治疗导致骨髓抑制（主要是放、化疗）引起的贫血。肿瘤相关性 贫血可以发生在肿瘤诊治的任何阶段，其发生与肿瘤类型、分期及治疗等因素密切相关。2012 年国内的调查显示，肿瘤相 关性贫血的发生率为60.83%，其中轻度贫血40.84%，中度贫血15.67%，重度贫血3.47%，极重度贫血0.84%。发病率较高的肿瘤分别为消化道癌、乳腺癌和肺癌等。研究显示，肿瘤相关性贫血会明显降低肿瘤患者的生活质量，影响治疗效果， 缩短生存期，增加死亡风险；而通过合理的治疗，纠正贫血后，可以改善患者的生活质量，提高生存率。肿瘤相关性贫血 的发病机制复杂，可能与肿瘤本身及其并发症（如肿瘤侵犯骨髓、溶血、失血、肿瘤相关性炎症等）、治疗手段引起的骨 髓抑制（化疗、放疗等）等有关。肿瘤相关性贫血的治疗目标为“提高生活质量，降低红细胞输注需求”。在病因治疗的 基础上，补充造血原料（铁剂、叶酸、维生素 B12 等），应用促红细胞生成素类药物及输红细胞治疗为其常用治疗手段。     

Influence of Fermentation and Drying Materials on the Contamination of Cocoa Beans by Ochratoxin A

Ochratoxin A (OTA) is a mycotoxin produced mainly by species of Aspergillus and Penicillium. Contamination of food with OTA is a major consumer health hazard. In Côte d’Ivoire, preventing OTA contamination has been the subject of extensive study. The current study was conducted to evaluate the influence of fermentation and drying materials on the OTA content in cocoa. For each test, 7000 intact cocoa pods were collected, split open to remove the beans, fermented using 1 of 3 different materials, sun-dried on 1 of 3 different platform types and stored for 30 days. A total of 22 samples were collected at each stage of post-harvesting operations. The OTA content in the extracted samples was then quantified by high-performance liquid chromatography. OTA was detected in beans at all stages of post-harvesting operations at varying levels: pod-opening (0.025 ± 0.02 mg/kg), fermentation (0.275 ± 0.2 mg/kg), drying (0.569 ± 0.015 mg/kg), and storage (0.558 ± 0.04 mg/kg). No significant relationships between the detected OTA level and the materials used in the fermentation and drying of cocoa were observed.     

Impact of Acoustic Radiation Force Excitation Geometry on Shear Wave Dispersion and Attenuation Estimates

Shear wave elasticity imaging (SWEI) characterizes the mechanical properties of human tissues to differentiate healthy from diseased tissue. Commercial scanners tend to reconstruct shear wave speeds for a region of interest using time-of-flight methods reporting a single shear wave speed (or elastic modulus) to the end user under the assumptions that tissue is elastic and shear wave speeds are not dependent on the frequency content of the shear waves. Human tissues, however, are known to be viscoelastic, resulting in dispersion and attenuation. Shear wave spectroscopy and spectral methods have been previously reported in the literature to quantify shear wave dispersion and attenuation, commonly making an assumption that the acoustic radiation force excitation acts as a cylindrical source with a known geometric shear wave amplitude decay. This work quantifies the bias in shear dispersion and attenuation estimates associated with making this cylindrical wave assumption when applied to shear wave sources with finite depth extents, as commonly occurs with realistic focal geometries, in elastic and viscoelastic media. Bias is quantified using analytically derived shear wave data and shear wave data generated using finite-element method models. Shear wave dispersion and attenuation bias (up to 15% for dispersion and 41% for attenuation) is greater for more tightly focused acoustic radiation force sources with smaller depths of field relative to their lateral extent (height-to-width ratios <16). Dispersion and attenuation errors associated with assuming a cylindrical geometric shear wave decay in SWEI can be appreciable and should be considered when analyzing the viscoelastic properties of tissues with acoustic radiation force source distributions with limited depths of field.     

通过FTIR与DSC分析医疗器械包装材料成分特性

介绍了医疗器械塑料包装材料的特性，通过FTIR和DSC简单快捷的分析了包装材料聚乙烯与聚丙烯的成分及聚合度，为以后相关医疗器械包装材料的残留单体及添加剂等有害物质分析确认提供参考。     

A New Approach Toward Metal‐Free Self‐Healing Ionomers Based on Phosphate and Methacrylate Containing Copolymers

In order to accelerate the progress of the development of new self‐healing ionomers, a new pathway toward fully organic ionomers containing methacrylic acid and phosphate‐based functional groups, respectively, as well as butyl methacrylate as comonomer is presented in the current study. The well‐defined copolymer structures are synthesized using the reversible addition‐fragmentation chain transfer polymerization and further characterized by NMR, size exclusion chromatography as well as titration. Two different metal‐free ionomers as well as one reference K⁺ based ionomer are created and tested. The results of the detailed investigation by NMR, thermal analysis, and rheology are correlated with the scratch‐healing performance in order to identify trends and dependencies leading to preconditions for further improvements.