钛硅涂层对钴铬合金耐腐蚀性能的影响

目的:研究钛硅(TiSi)涂层对牙科钴铬合金(CoCr)耐腐蚀性能的影响。方法:选用临床常用的CoCr合金,制作成10mm×10mm×3mm规格的试件,运用溶胶-凝胶法在其表面涂层钛硅。将涂层前、后的试件浸泡在人工唾液中,利用失重法计算材料的腐蚀速度,并运用ICP-AES等离子体发射光谱仪分析钴铬合金钛硅涂层前、后离子释放量的差异,采用SAS8.0软件包对数据进行统计学分析。结果:失重法实验发现,钛硅涂层前的腐蚀速度为0.163g·m-2·h-1;涂层后为0.138 g·m-2·h-1,运用AES技术分析钴铬合金的元素释放量(g·m-2),涂层前镍为7.728582657、钴为0.008801153、铬为0.306195965、硅为0.194851978;而涂层后,镍为4.745189808、钴为0.004718889、铬为0.153195362、硅为0.778406136,镍、钴、铬的元素释放量在涂层后减少。结论:硅钛涂层能提高钴铬合金的耐腐蚀性能。     

Impact de l’élimination du gel fluoré résiduel sur la corrosion des attaches en titane

Introduction

Fluoride ions, in long-term applications on titanium brackets, cause their corrosion. Fluoride gel used for caries prevention during orthodontic treatment has a very high concentration in fluoride ions, and therefore has the potential for causing bracket corrosion. The main aim of this study was to determine the effect of eliminating the residual fluoride gel, by rinsing it, on the corrosion of titanium brackets. The secondary aim was to evaluate the corrosion of titanium brackets in the presence of fluoride gel.

Methods

One hundred titanium brackets were divided into five groups of 20 brackets each. Group 1 being the control group, the rest of the groups were immersed in fluoride gel: Group 2 for 4 minutes and kept for 30 minutes with the residual fluoride gel on; Group 3 for 4 minutes followed by immediate water rinsing; Group 4 for 12 minutes and kept for 90 minutes with the residual fluoride gel on and Group 5 for 12 minutes followed by immediate water rinsing. All groups were rinsed then dried, for 20 hours, using Silica gel in a desiccator maintained at 37 °C before testing.

Results

Gravimetrical results and SEM analysis showed no significant difference between Groups 2, 3 and 5 compared to each other and to the control group. Only Group 4 showed significant weight loss and pitting corrosion in four of the 20 brackets. In sliding resistance, no significant difference was detected between any of the groups.

Conclusions

Short time applications of fluoride gel do not affect sliding resistance of titanium brackets. No titanium corrosion was detected for one application of concentrated fluoride gel and some brackets showed pitting corrosion for three applications. The rinsing of residual fluoride gel eliminates completely the risk of bracket corrosion.     

Cyclic Fatigue Resistance of Three Different Nickel-Titanium Instruments after Immersion in Sodium Hypochlorite

Introduction

The purpose of this study was to assess the resistance to cyclic fatigue of three nickel-titanium (NiTi) files after the immersion in sodium hypochlorite (NaOCl) solution in conditions similar to those used in clinical practice.

Methods

A total of 150 new Twisted Files (SybronEndo, Orange, CA), Revo S SU files (Micro Mega, Besancon, France), and Mtwo files (Sweden and Martina, Padova, Italy), size 25.06, were tested. Fifty files of the same brand were randomly assigned to five groups (n = 10) and submitted to the following immersion protocol in 5% NaOCl at 37°C for 16 mm: no immersion (control), 5 minutes statically, 1 minute statically, 5 minutes dynamically (300 rpm/min), and 1 minute dynamically. Resistance to cyclic fatigue was determined by counting the numbers of cycles to failure in a 60° curve with a 5-mm radius. Data were analyzed by two-way analyses of variance.

Results

Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl (P > .05). The Twisted File showed a higher resistance in all groups than Revo S SU (P < .001). The comparison between the same groups of Twisted Files and Mtwo files or between Mtwo and Revo S files did not show significant differences (P > .05) except for two cases: group 2 of the Twisted Files and Mtwo files and group 5 of the Mtwo and Revo S SU files (P < .05).

Conclusions

Static or dynamic immersion in NaOCl for 1 minute or 5 minutes did not reduce the cyclic fatigue resistance of NiTi significantly. However, the type of instrument influences cyclic fatigue resistance. In our study, Twisted Files were more resistant followed by Mtwo and Revo S SU files.     

阳极氧化及等离子渗氮对纯钛腐蚀性能的影响

目的：模拟口腔环境,研究阳极氧化纯钛试样及等离子渗氮纯钛试样在pH=6.8的人工唾液中的腐蚀情况。方法：采用塔菲尔（tafel）曲线测试,测定阳极氧化纯钛试样及等离子渗氮纯钛试样在pH=6.8的人工唾液中的自腐蚀电流密度（Icorr）,并以自然氧化纯钛试样为对照组进行比较分析。场发射扫描电镜（FSEM）观察不同纯钛试样腐蚀前后形貌。结果：阳极氧化及等离子渗氮对纯钛腐蚀性的影响均有显著性,P〈0.05。Icorr均明显减小,腐蚀速度减慢。阳极氧化纯钛试样在pH=6.8的人工唾液中Icorr最小,耐腐蚀性能好。结论：阳极氧化及等离子渗氮两种表面处理方法可以显著提高纯钛试样在pH=6.8的人工唾液中的耐腐蚀性;进行阳极氧化表面处理后纯钛试样的耐腐蚀性能更优。     

生物医用镍钛合金表面钽涂层腐蚀行为研究

目的 在模拟体液环境中,研究钽(tantalum, Ta)涂层对生物医用镍钛形状记忆合金(NiTi shape memory alloy, NiTi SMA)抗腐蚀性能的影响.方法 对镍钛形状记忆合金试样,运用等离子喷涂技术在其表面形成一层400μm厚的钽涂层.通过模拟体液环境下电化学测量法对比涂层前后的试样抗腐蚀性能...     

Effect of surface pre-treatments on biocompatibility of magnesium

This study reports the influence of Mg surface passivation on the survival rate of human HeLa cells and mouse fibroblasts in cell culture experiments. Polished samples of commercially pure Mg show high reactivity in the cell culture medium, leading to a pH shift in the alkaline direction, and therefore cell adhesion and survival is strongly impaired. Passivation of the Mg surface in 1 M NaOH can strongly enhance cell survival. The best initial cell adhesion is observed for Mg samples incubated in simulated body fluid (M-SBF), which leads to the formation of a biomimetic, amorphous Ca/Mg-phosphate layer with high surface roughness. This surface layer, however, passivates and seals the Mg surface only partially. Subsequent Mg dissolution leads to a significantly stronger pH increase compared to NaOH-passivated samples, which prevents long-term cell survival. These results demonstrate that surface passivation with NaOH and M-SBF together with the associated changes of surface reactivity, chemistry and roughness provide a viable strategy to facilitate cell survival on otherwise non-biocompatible Mg surfaces.     

消毒煮沸器在区级医院使用的探讨

目的探讨区级医院消毒供应室使用消毒煮沸器进行器械消毒的效果。方法随机将门诊小手术器械240件分为A、B两组。A组器械在常规手工清洗后浸泡在含氯消毒液（含有效氯500mg／L）中30min,B组器械常规手工清洗后用煮沸器90℃煮沸消毒5min,每2天分别作细菌培养,对比两组器械的细菌数及器械使用1个月后的锈蚀情况及锐性器械（剪刀）的锐利度。结果两组手术器械消毒后进行细菌培养比较,结果均为全部合格：锈蚀率及锐利度比较,B组明显优于A组,两组差异有统计学意义（P〈0．05）。结论区级医院或基层医院消毒供应室在没用清洗消毒机的情况下,器械使用煮沸器进行煮沸消毒,符合器械清洗质量标准,能达到提高工作质量、效率和降低物耗的目的,也减少了环境污染与职业暴露的风险。     

Hank’s溶液中NiTi形状记忆合金微动和腐蚀交互作用的研究

通过对近待原子比NiTi形状记忆合金在Hank’s溶液的微动腐蚀行为的研究发现，在微动条件下，化学腐蚀和微动磨损交互作用用使得NiTi　SMA失厚比上述二者单独存在时严重，即化学腐蚀因微动磨损而加剧，腐蚀也进一步加大了微动磨损。在Hank’s溶液中合金的失厚来自于五个方面：纯化学腐蚀、微动磨损、微动磨损引起的化学腐蚀、化学腐蚀引起的微动磨损及微动磨损与化学腐蚀的交互作用。在Hank＇s溶液中微动磨损引起的失厚远远大于微动磨损与化学腐蚀交互作用引起的失厚，合金在Hank’s溶液中微动磨损的主要形式是黏着磨损和磨粒磨损。     

人工龋形成的电化学机理研究

目的：研究人工龋形成的电化学腐蚀机理。方法：采用循环伏安法、失重法观察牙片在K2S04溶液中的氧化还原行为及在KCl和K2SO4介质中恒电位腐蚀情况，并监测电解液氢离子浓度的变化情况。结果：在0．0V—2．5V电位范围内，牙片电极与石墨电极具有波形相似的循环伏安曲线；在KCl和K2SO4介质中牙片的腐蚀速度无显著差异；2．0V恒电位腐蚀牙片8h后，阳极池本体溶液pH值为3．87，阴极池pH值为10．65。结论：在外电场作用下，牙片的阳极腐蚀与介质无关；电化学人工龋形成的主要决定因素是牙齿发生酸溶。     

Ti-Fe-Mo-Mn-Nb-Zr合金在不同pH值乳酸中的腐蚀性能研究

对应口腔环境中 p H值发生明显变化以及形成龋齿的自然现象 ,采用加速试验法研究了新型钛合金在不同 p H值乳酸中浸泡的耐腐蚀性能。研究表明当 p H=4即酸性略高于龋齿发病时酸性条件下 ,新型牙科钛合金能够完全耐乳酸腐蚀。在乳酸中腐蚀形式以点蚀为主 ,且随酸性增强有向晶间腐蚀转变的趋势。ICP分析表明合金在乳酸中的溶解析出物主要是 Fe,Fe的加入不利于合金的耐腐蚀性能。热力学计算表明设计的新型钛合金氧化膜含有 Mn2 O3、Nb2 O5、Zr O2 和 Ti O2 中的全部或部分 ,XPS分析表明氧化膜中的确含有 Mn2 O3、Nb2 O5和 Ti O2 ,主要是 Ti O2 。这三种氧化物致密且 Ti O2 和 Nb2 O5耐腐蚀 ,有利于合金的耐腐蚀性能。