Influence of water, loading rate and bonder on the adhesion of porcelain to titanium

OBJECTIVES: The aim of this study was to measure the influence of water on the adhesion between titanium and porcelain by means of the strain energy release rate (G-value or interfacial toughness). METHODS: Rectangular specimens of grade II titanium and a reference gold-palladium porcelain fused to metal (PFM) alloy were veneered with feldspathic porcelains. In the case of the titanium, two gold and one ceramic bonder systems were used to enhance the adhesion of the porcelain. The G-value was measured with a four-point bending configuration developed by Charalambides et al. (Journal of Applied Mechanics (Trans ASME). 1989;56:77-82), at four different loading rates (from 0.1 to 15 N/s) in water and at one loading rate (1.5 N/s) in kerosine. RESULTS: There was a significant difference (ANOVA, p<0.01) in the interfacial toughness between the different bonding systems, with the two goldbonder systems exhibiting higher toughness in kerosine and water than the ceramic bonder. The two goldbonders achieved the best results across all loading rates. Their interfacial toughness, tested in kerosine, varied between 45.83+/-6.72 and 73.54+/-17.01 J/m(2) and tested in water from 40.86+/-2.23 to 69.17+/-12.33 J/m(2), respectively. The ceramic Ti bonder achieved the lowest G-values throughout (30.15+/-5.52 J/m(2) in kerosine to 11.08+/-2.18 J/m(2) in water). The gold-palladium PFM alloy showed more constant behaviour (33.48+/-2.24 J/m(2) to 23.07+/-0.53 J/m(2) in kerosine and water, respectively). CONCLUSION: Compared to the gold-palladium PFM alloy, the goldbonders achieved much higher G-values whereas the ceramic Ti bonder G-values were lower when tested in water and in kerosine.     

离子色谱-抑制电导法测定硫酸镁钠钾口服用浓溶液中镁、钠、钾离子

目的 建立离子色谱–抑制电导法同时测定硫酸镁钠钾口服用浓溶液中镁、钠、钾离子的方法。方法 采用Dionex IonPac^TM CS12A色谱柱（250 mm×4 mm）,Dionex IonPac^TM CG12A保护柱（50 mm×4 mm）;以甲烷磺酸溶液为洗脱液,梯度洗脱,体积流量为1.0 mL/min,柱温30 ℃,检测池温度35 ℃,电导检测器,抑制器为Dionex CDRS 600 4 mm,电流值117 mA,进样体积为25 μL。结果 镁在0.72～1.08μg/mL、钠在12.80～19.20 μg/mL、钾在3.20～4.80 μg/mL线性关系良好,平均回收率分别为101.0%、100.7%、102.9%,RSD值分别为1.4%、1.4%、0.7%。结论 该方法简单、快速、准确,能够有效地控制硫酸镁钠钾口服用浓溶液中镁、钠、钾离子。     

合并骨质疏松且无低血镁的Gitelman综合征1例

目的 探讨Gitelman综合征（GS）合并重度骨质疏松的临床特点、诊断和治疗,加深对该病的认识。方法 2017年2月海南医学院第二附属医院内分泌科住院的GS合并重度骨质疏松且无低血镁1例,复习文献,总结该病特点。结果 该病主要表现为严重低钾血症、多处骨关节疼痛,易误诊。予积极补钾、抗醛固酮、抗骨质疏松治疗,有效缓解了病情。结论 GS虽然尿钙低,无低血镁,但也可以合并骨质疏松。因此,对存在多关节疼痛的GS病人,应及时进行双能X线骨密度检查早期筛查骨质疏松。对于此类病人,积极给予补钾、抗醛固酮及抗骨质疏松治疗可提高疗效。     

槲皮素对低钙高镁饮食大鼠血清矿量和骨代谢的改善作用

目的观察槲皮素对低钙高镁饮食大鼠血清矿量和骨代谢水平的改善作用,为骨质疏松临床预防提供参考。方法将60只清洁雄性SD成年黑色大鼠随机等分为空白对照组、模型对照组和槲皮素喂养组,每组20只。空白对照组实验过程中均正常喂养,模型对照组和槲皮素喂养组均适应性喂养2周后,进行低钙高镁(钙5 mg/L,镁60 g/L,蒸馏水溶液作为饮用水)喂养3个月,槲皮素喂养组给予低钙高镁喂养期间同时给予槲皮素(2.64 kg/d)。观察各组大鼠的日常饮食量、饮水量、体重、毛发、毛发色泽、活动等一般情况,分别于低钙高镁喂养前(实验前)和给药喂养3个月时(实验后)两个时刻点进行血清矿量(血钙、血镁、血磷)及骨代谢指标(BALP、CTX-1、BGP、t PINP)测定。结果实验期间,空白对照组、模型对照组和槲皮素喂养组大鼠的日常饮食量、饮水量、体重比较无显著差异(P0.05),但空白对照组、槲皮素喂养组实验大鼠更具活力,毛发更光润。模型对照组大鼠实验后的血钙量、血磷量、BALP均下降,血镁量、BGP、CTX1、t PINP均提升,与实验前比较差异有统计学意义(P0.05)。槲皮素喂养组大鼠实验后的血钙量、血磷量、BALP均显著高于模型对照组大鼠实验后(P0.05),槲皮素喂养组大鼠实验后的血镁量、BGP、CTX1、t PINP均显著低于模型对照组大鼠实验后(P0.05)。结论槲皮素可显著改善低钙高镁饮食大鼠血清矿量和骨代谢水平,可能在低钙高镁交互作用诱导骨质疏松症的预防中起到重要作用。     

Metallurgical and interfacial characterization of PFM Co–Cr dental alloys fabricated via casting,milling or selective laser melting

Objectives

Bulk and interfacial characterization of porcelain fused to metal (PFM) Co–Cr dental alloys fabricated via conventional casting, milling and selective laser melting.

Methods

Three groups of metallic specimens made of PFM Co–Cr dental alloys were prepared using casting (CST), milling (MIL) and selective laser sintering (SLM). The porosity of the groups was evaluated using X-ray scans. The microstructures of the specimens were evaluated via SEM examination, EDX and XRD analysis. Vickers hardness testing was utilized to measure the hardness of the specimens. Interfacial characterization was conducted on the porcelain-covered specimens from each group to test the elemental distribution with and without the application of INmetalbond. The elemental distribution of the probed elements was assessed using EDX line profile analysis. Hardness results were statistically analyzed using one-way ANOVA and Holm–Sidak's method (α = 0.05).

Results

X-ray radiography revealed the presence of porosity only in the CST group. Different microstructures were identified among the groups. Together with the γ phase matrix, a second phase, believed to be the Co₃Mo phase, was also observed by SEM and subsequent XRD analysis. Cr₇C₃ and Cr₂₃C₆ carbides were also identified via XRD analysis in the CST and MIL groups. The hardness values were 320 ± 12 HV, 297 ± 5 HV and 371 ± 10 HV, and statistically significant differences were evident among the groups.

Significance

The microstructure and hardness of PFM Co–Cr dental alloys are dependent on the manufacturing technique employed. Given the differences in microstructural and hardness properties among the tested groups, further differences in their clinical behavior are anticipated.     

Cytotoxicity of alloying elements and experimental titanium alloys by WST-1 and agar overlay tests

ObjectiveThis study was performed to evaluate the biocompatibility of nine types of pure metals using 36 experimental prosthetic titanium-based alloys containing 5, 10, 15, and 20 wt% of each substituted metal.MethodsThe cell viabilities for pure metals on Ti alloys that contain these elements were compared with that of commercially pure (CP) Ti using the WST-1 test and agar overlay test.ResultsThe ranking of pure metal cytotoxicity from most potent to least potent was: Co > Cu > In > Ag > Cr > Sn > Au > Pd > Pt > CP Ti. The cell viability ratios for pure Co, Cu, In, and Ag were 13.9 ± 4.6%, 21.7 ± 10.4%, 24.1 ± 5.7%, and 24.8 ± 6.0%, respectively, which were significantly lower than that for the control group (p < 0.05). Pure Pd and Pt demonstrated good biocompatibility with cell viabilities of 93.8 ± 9.6% and 97.2 ± 7.1%, respectively. The Ti–5Pd alloy exhibited the highest cell viability (128.4 ± 21.4%), which was greater than that of CP Ti. By alloying pure Co or Cu with Ti, the cell viabilities for the Ti–xCo and Ti–xCu alloys increased significantly up to 10 wt% of the alloying element followed by a gradual decrease with a further increase in the concentration of the alloying element. Based on the agar overlay test, pure Ag, Co, Cr, Cu, and In were ranked as ‘moderately cytotoxic’, whereas all Ti alloys were ranked as ‘noncytotoxic’.SignificanceThe cytotoxicity of pure Ag, Co, Cr, Cu, and In suggests a need for attention in alloy design. The cytotoxicity of alloying elements became more biocompatible when they were alloyed with titanium. However, the cytotoxicity of titanium alloys was observed when the concentration of the alloying element exceeded its respective allowable limit. The results obtained in this study can serve as a guide for the development of new Ti-based alloy systems.     

Magnesium ions facilitate integrin alpha 2‐ and alpha 3‐mediated proliferation and enhance alkaline phosphatase expression and activity in hBMSCs

Magnesium metal and its alloys have been proposed as a novel class of bone implant biomaterials because of their biodegradability and mechanical properties. The purpose of this study was to determine whether magnesium ions, which are released abundantly from alloys, affect proliferation and differentiation of human bone marrow‐derived stromal cells (hBMSCs). High levels of magnesium ions did not induce cytotoxicity in hBMSCs, but treatment with 2.5–10 mm magnesium ions for 48–72 h significantly increased hBMSC proliferation. The expression of integrins α2 and α3, but not β1, was upregulated compared with the control and shifted from α3 to α2 in hBMSCs treated with magnesium ions. Knockdown of integrins α2 and/or α3 significantly reduced magnesium‐induced proliferation of hBMSCs. Magnesium exposure profoundly enhanced alkaline phosphatase (ALP) gene expression and activity even at a relatively low magnesium concentration (2.5 mm ). Exposure to magnesium ions facilitated hBMSC proliferation via integrin α2 and α3 expression and partly promoted differentiation into osteoblasts via the alteration of ALP expression and activity. Accordingly, magnesium could be a useful biomaterial for orthopaedic applications such as bone implant biomaterials for repair and regeneration of bone defects in orthopaedic and dental fields. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparison of nebulised magnesium sulphate and salbutamol combined with salbutamol alone in the treatment of acute bronchial asthma: a randomised study

Objective

To test the hypothesis that combined administration of multiple doses of nebulised salbutamol and magnesium sulphate provides additional benefit compared with salbutamol alone in adult patients with acute asthma.

Design

Randomised, double blind, prospective study.

Methods

A total of 100 patients presenting to an emergency department with an acute attack of bronchial asthma were randomised to two groups: nebulisation with a combination of salbutamol and magnesium sulphate (group A) and nebulisation with salbutamol only (group B). Both groups received nebulisation thrice at intervals of 20 minutes. Salbutamol and magnesium sulphate were administered in doses of 0.5 mg and 500 mg, respectively, and the solutions were made isotonic to plasma osmolality. Pulse rate, blood pressure, and peak expiratory flow rate (PEFR) were measured at baseline and at 15, 60, 75, and 120 minutes. Serum magnesium levels and blood gases were measured at 0 and 120 minutes in both groups.

Results

All patients had either acute severe or life threatening asthma. The baseline characteristics were comparable in the two groups. Both groups showed significant rise in PEFR at all time intervals, however, there was no significant difference between the groups in rise in PEFR at any time point. Serum magnesium levels remained within normal limits, and there was no difference in requirement of additional medication during the study or hospital admission rates in both groups. No significant side effects were noted.

Conclusion

This study suggests that there is no therapeutic benefit of adding magnesium sulphate to salbutamol nebulisation in the treatment of patients with acute severe or life threatening asthma.     

天鹅记忆接骨器对骨折愈合中皮质骨胶原构筑的影响

目的 探讨天鹅记忆接骨器（SMC）对实验性骨折愈合中皮质骨胶原构筑的影响。方法 20只新西兰大白兔双侧肱骨干截骨后，随机选取一侧用SMC固定，对侧用4孔动力加压接骨板（DCP）固定，分别在术后2、4、8、16、32周时各处死4只动物取材，扫描电镜观察固定段皮质骨胶原构筑的变化。结果 SMC组在整个固定过程中，皮质骨结构与正常对照组相比无明显变化。而DCP组术后4周，胶原排列出现稀疏，局部有小吸收陷窝形成；术后8周，胶原排列紊乱，且有多个吸收腔形成；术后16周，DCP组胶原纤维出现中断；术后32周，DCP组骨质松化更加明显。结论SMC具有材料特性和几何构型上的优势，不仅对骨干不产生应力遮挡效应，而且对骨血供损伤也非常轻，故能有效防止骨质疏松的发生。     

Magnesium Content of Mononuclear Blood Cells in Migraine Patients

SYNOPSIS
Recent research has shown that magnesium levels in serum, salivary secretions and red blood cells are reduced in migraine patients with and without aura, both ictally and interictally. This suggests that lower magnesium levels can contribute to the etiopathogenetic mechanisms underlying migraine attacks. It has been suggested that mononuclear magnesium content is a reliable index of magnesium nutritional status, as it is more closely related to the total body stores than other biochemical indices. Therefore we determined mononuclear magnesium content in adult migraine patients with and without aura, in headache-free periods and, in a number of patients, during attacks. Migraine patients with and without aura, assessed in interictal periods, had a reduced mononuclear magnesium content compared to age-matched healthy control subjects. No significant variations were observed between ictal and interictal periods in migraine patients with aura and without aura. The lower magnesium content in mononuclear cells could indirectly indicate the reduction of brain magnesium concentration, which has recently been demonstrated in the course of migraine.