Screening of Solid and Porous Materials for Pacemaker Electrodes

Several different materials, including one which was porous, were studied to assess their properties as pacemaker electrode tips. Leads were implanted in sheep for periods up to one year. Electrical measurements were made during the implant period and histopathological examination performed after sacrifice. Although titanium vapor-deposited carbon, and silver did not lower the chronic stimulation threshold below that of platinum, their electrical characteristics were within generally acceptable limits. Zinc evoked a severe tissue reaction and a high threshold. Porous titanium alloy electrodes demonstrated reduced dislodgement, more frequent attachment and a lower sensing impedance than other electrodes.     

An Assessment of the Effect of Synthetic and Doping Conditions on the Processability and Conductivity of Poly(3,4‐ethylenedioxythiophene)/Poly(styrene sulfonic acid)

Poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) dispersions are synthesized via conventional oxidative polymerization under various synthetic (reaction times and formulations) and doping conditions (in situ and postpolymerization) with the introduction of dialysis as an additional purification step. Conductivities of films produced from these synthesized dispersions are one to three orders of magnitude higher than the equivalent commercial PEDOT/PSS reference film. In situ doped PEDOT/PSS dispersions give films that are more conductive than those doped postpolymerization. Optimum conductivity of 5.2 ± 0.7 S cm^?1 is obtained from PEDOT/PSS dispersions (1:2.5 EDOT:PSS mass ratio) synthesized for 12 h with doping efficiency of 73%. Under these synthetic conditions, the film most likely has the optimal microstructure, i.e., optimal PEDOT chain length and ideal distribution and balance of PEDOT/PSS segments and free PSS chains, favoring charge transport and processability. Capillary electrophoresis is presented here as a novel method for measuring free and doped PSS in PEDOT/PSS dispersions.

     

iRoot SP与Cortisomol糊剂对一次性根管治疗术后发生急症反应的影响

目的：比较iRoot SP根管充填材料与Cortisomol根管充填糊剂对一次性根管治疗术后患者发生急症反应的影响,为材料的选择提供参考。方法选择我院2015年9月至2016年3月口腔门诊牙髓炎及慢性根尖周炎患者86例,采用数表法随机分为两组,A组43例(47颗恒牙)采用iRoot SP根管充填材料,B组43例(46颗恒牙)采用Cortisomol根管充填糊剂,比较两组患者术后1~2 d和7 d的急症反应发生情况。结果两组患者术后1~2 d急症反应发生率均为4.65%,7 d急症反应发生率均为2.33%,差异均无统计学意义(P>0.05)。结论 iRoot SP根管充填材料与Cortisomol根管充填糊剂术后急症反应发生率均较低,但两种材料的特点不同,可根据需要选择使用。     

Characterization of silver particles in the stratum corneum of healthy subjects and atopic dermatitis patients dermally exposed to a silver-containing garment

Silver is increasingly being used in garments to exploit its antibacterial properties. Information on the presence of silver nanoparticles (AgNPs) in garments and their in vivo penetration across healthy and impaired skin from use is limited. We investigated the presence of AgNPs in a silver containing garment and in the stratum corneum (SC) of healthy subjects (CTRLs) and individuals with atopic dermatitis (AD). Seven CTRLs and seven AD patients wore a silver sleeve (13% Ag w/w) 8?h/day for five days on a forearm and a placebo sleeve on the other forearm. After five days, the layers of the SC were collected by adhesive tapes. The silver particles in the garment and SC were characterized by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and atomic force microscopy (AFM). AFM and SEM revealed the presence of sub-micrometre particles having a broad range of sizes (30–500?nm) on the surface of the garment that were identified as silver. On the SC tapes collected from different depths, aggregates with a wide range of sizes (150?nm–2?μm) and morphologies were found. Most aggregates contained primarily silver, although some also contained chlorine and sulfur. There was no clear difference in the number or size of the aggregates observed in SC between healthy and AD subjects.

After use, AgNPs and their aggregates were present in the SC at different depths of both healthy subjects and AD patients. Their micrometre size suggests that aggregation likely occurred in the SC.     

三种材料修复根面龋的临床效果观察

目的 :探讨修复根面龋较理想的材料。方法 :选择 1 92颗根面龋患牙 ,分别采用银汞合金、光固化复合树脂和银粉玻璃离子充填修复。随访观察 2年。结果 :三种材料修复成功率分别为 5 3 2 3% ,75 86 %和 88 89%。银汞合金与光固化复合树脂两种材料修复成功率有显著性差异 (P <0 0 1 ) ;银汞合金与银粉玻璃离子两种材料修复成功率有显著性差异 (P <0 0 1 ) ;银粉玻璃离子与光固化复合树脂两种材料修复成功有显著性差异 (P <0 0 5 )。结论 :银粉玻璃离子是修复根面龋较为理想的材料 ,其疗效优于银汞合金与光固化复合树脂     

Effect of surface treatment on etched procelain bond strength to enamel

The purpose of this study was to evaluate the effect of mechanical retention by etching and chemical bonding by silanizing porcelain surfaces on their shear bond strength to etched enamel. The individual contributions of the two processes were compared with the bond strength obtained by the combined treatment. The effect of applying fit-checker paste to etched porcelain surface was also examined before and after re-etching. The 5 groups were compared between Mirage shade A₂ (N=25) and Mirage shade 65 (N=25) porcelains. Following surface treatment of porcelain and resin bonding to etched enamel, the specimens were thermocycled 600 times between 5° and 55°C and debonded in shear mode. Results indicated that, overall, Mirage shade 65 porcelain was twice as strong as Mirage shade A₂. However, the 5 treatment groups for each shade showed remarkable similarity, with the highest bond achieved by both etching and silanizing the porcelain. The bond strength from etching or silanizing alone was not significant. Use of a fit-checker paste lowered the bond strength, possibly by chemical contamination. There was no evidence of physical obliteration of the microporosities on the etched surface with the use of a silane coupling agent or the fit-checker if removed completely. It was concluded that optimum bond strength of porcelain to etched enamel is obtained by both etching and silanizing the surface. Caution should be exercised when using a silicone-based fit-checker paste. Further study is recommended.     

Author Index of Volume 562

A simple, accurate, precise and sensitive potentiometric assay for the determination of acetycholine (Ach) in pure and biological samples is described. The method is based on the construction of an Ach sensor using carbon paste containing 1–10% (w/w) 2,3,6-trimethyl o-β-cyclodextrin doped as an ionophore with tricresyl phosphate (TCP) (a plasticizer) and potassium tetrakis-p-chlorophenyl borate (TKB). The increase in the potentiometric response of the carbon paste electrode CPE toward Ach is characterized by a slope of 57.4 ± 0.5 mV/decade in the range of 10³–10^?5 M Ach solution. The detection limit and correlation factors are calculated. The optimization of various experimental conditions is described. A successful application of the new CPE to determine Ach in the homogenates of cotton leaf worm “Spodoptera littoralis” is presented.     

三种无机抗菌剂对常见牙体牙周致病菌的抗菌效果

目的 比较三种国内纳米级载银无机抗菌剂对口腔病原菌的抗菌活性。方法 采用微量板液体稀释法，测定GKJ-R、Conval PAg-40、TiO2／Ag三种纳米级载银无机抗菌剂对变形链球菌（ATCC140）、乳酸杆菌（ATCC393）、粘性放线菌（ATCC19246）、牙龈卟啉单胞菌（ATCC25261）的最小杀菌浓度（MBC）。结果 三种纳米级载银无机抗菌剂对变形链球菌、乳酸杆菌、粘性放线菌、牙龈卟啉单胞菌均有良好的杀菌效果，且抗菌能力没有显著区别。结论 为纳米载银无机抗菌剂在牙科抗菌材料领域应用提供理论依据。     

Vitapex糊剂和抗生素糊剂用于根尖诱导成形术的疗效比较

目的:观察两种根充糊剂对根尖诱导成形的作用。方法:选择年轻恒牙172颗,其中牙髓炎62颗、牙髓坏死32颗、根尖周炎78颗,随机分成两组,分别充填Vitapex糊剂和抗生素糊剂,随访3a评价其疗效。结果:总治疗有效率Vitapex组为86.0%,抗生素组为91.9%,差异无显著性(P>0.05);但在根尖周炎组两者差异有显著性(P<0.05)。结论:Vitapex和抗生素糊剂都是较理想的根尖诱导制剂,但Vitapex糊剂要注意适应证的选择。     

根管糊剂在ObturaⅡ充填技术中对根尖微渗漏的影响

目的:探讨在Obtura Ⅱ注射式热熔牙胶充填中,不同根管糊剂对根尖微渗漏的影响。方法:40颗单根管牙随机分为4组,采用Obtura Ⅱ注射式热熔牙胶进行根管充填,A、B、C组分别以ZOE、Vitapex、AHplus作为根管糊剂,D组未用糊剂。充填后行墨汁渗透实验,制作透明标本,使用体视显微镜和显微照相系统观测染料渗透的长度。结果:染料自根尖孔渗入根管的长度,D组最长,为4.56±2.72mm,与A、B、C组间差异均有显著性(P<0.05)。在使用糊剂的实验组中,染色线的长度由小到大依次是AHplus1.70±0.82mm、Vitapex1.87±0.56mm和ZOE2.02±0.40mm,但3组之间没有统计学差异(P>0.05)。结论:根管糊剂的使用能显著降低Obtura Ⅱ根管充填后根尖的微渗漏。