Is Oxidized Zirconium Femoral Head Superior to Other Bearing Types in Total Hip Arthroplasty? A Systematic Review and Meta-Analysis

BackgroundOxidized zirconium (OxZi) is a relatively new type of material that combines the strength of a metal with the surface/wears properties of a ceramic. Our aim was to investigate whether OxZi femoral heads lead to lower polyethylene wear, higher survival rate, and better clinical outcomes than the other bearing types in patients treated with total hip arthroplasty (THA).MethodsTwo reviewers independently conducted a systematic search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews. These databases were queried with the terms: a. “oxidized” AND “zirconium” AND “total” AND “hip” AND “arthroplasty”; b. “oxinium” AND “total” AND “hip” AND “arthroplasty”. The primary outcome measures were the survival rate of the bearing surfaces as well as the polyethylene wear.ResultsThe vast majority (85.7%) of the studies, which reported the mean polyethylene wear rate, showed that there was not any significant difference between OxZi and cobalt-chrome (CoCr) femoral heads (rate ratio: 0.836; 95% confidence interval: 0.362-1.928; P = .674). All studies comparing the survival rate of OxZi and CoCr femoral heads illustrated almost excellent survivorship with both implants.ConclusionOxZi femoral heads did not lead to lower polyethylene wear rate or higher survival rate, when compared with CoCr femoral heads in patients treated with THA. On the basis of these results and taking into account the higher cost of these implants, we would not recommend the routine use of OxZi femoral heads in primary THAs.Level of EvidenceSystematic review and meta-analysis of therapeutic studies I-III.     

Stereological analysis of microvascular parameters in a double transgenic model of Alzheimer's disease

Morphological alterations in microvasculature occur as a common finding in the brains of non-demented aged persons and patients with Alzheimer's disease. Quantifying the extent of this vascular pathology, however, has been complicated by systematic error (bias) associated with the applications of assumption- and model-based morphometric techniques to human and animal tissues. The current study used novel assumption- and model-free stereological approaches to quantify capillary parameters in the corpus callosum of a double amyloid precursor protein/presenilin-1 transgenic murine model of Alzheimer's disease. The results revealed significant reductions in the total number of capillary segments in white matter of transgenic mice compared to non-transgenic littermates, with no differences in total capillary length. These findings support the view that the expression of mutant human genes for beta-amyloid peptides alters the normal architecture of cerebral capillary vessels in the white matter of mouse brain, which may model microvasculature changes reported in Alzheimer's disease.     

不同止血方式在新生儿PICC置管后的效果观察

目的 探讨新生儿PICC置管后有效的止血方式及减少肢体肿胀的方法.方法 对在我科住院治疗的132例需置入PICC管的患儿,在常规护理的基础上随机分为实验组和对照组各66例.对照组采用2×2cm的纱块按压穿刺点,外部用折叠后的绷带缠绕加压;实验组采取我科自制的纱球,如花生米粒大小（约0.5×0.8cm）,用其按压穿刺点局部,然后在其外部以透明敷贴加压,观察两组患者穿刺点渗血情况以及肢体肿胀情况.结果 观察组在穿刺点止血及穿刺侧肢体肿胀方面明显优于对照组（P＜0.05）,两组差异具有统计学意义.结论 采用自制消毒纱球作点状按压能达到快速止血的效果并且能够减少肢体肿胀的发生.     

Conical crowns with electroplated gold copings: retention force changes caused by wear and combined off‐axial load

Objectives: The aim of this study was to examine the wear behavior of conical crowns of gold alloy and zirconium dioxide ceramics facing electroplated gold copings. Methods: The conical crowns were milled in Group A of a cast gold alloy (Degunorm^®, DeguDent^®) and B zirconium dioxide (Cercon^®, DeguDent^®). Fifteen specimens were milled per group with a conicity of 2°. The electroplated coping was established by direct electroforming with the Solaris system (DeguDent^®) and glued into a framework. An apparatus accomplishing 5000 wear cycles performed the wear test. After each of the cycles, extra axial forces (80 N) were loaded 1 million times on an extension of the framework. The retentive forces and the correlating distance during insertion and separation were measured. The wear test was separated in a start phase, an initial wear phase and the long‐term wear period. The retention force value and the force–distance integral of the first 0.3 mm of each cycle were calculated. Results: The changes of retention force (ΔF) and integral (ΔF_d) differed significantly between both groups in the start phase (ΔF: A ?1.85 N, B +1.39 N, P=0.0028; ΔF_d: A ?0.155 N mm, B +0.2685 N mm, P=0.0378) and the initial wear phase. The long‐term wear period showed no differences in force and integral development. As a statistical test for the comparison of the median values of the two groups, the Mann–Whitney test was used. The median force never fell below 4 N or exceeded 12 N. Conclusions: Within the limitations of this study, the conical crowns tested showed clinically acceptable retentive properties. The values of about 4–6 N mentioned as sufficient in the recent literature were always attained. As the most retentive elements for dentures, both groups showed the main changes in retentive forces during the first 2000 cycles. The retention force development of the zirconia group appears to be less excursive over the whole wear test. To cite this article:
Bayer S, Zuziak W, Kraus D, Keilig L, Stark H, Enkling N. Conical crowns with electroplated gold copings: retention force changes caused by wear and combined off‐axial load.
Clin. Oral Impl. Res. 22 , 2011; 323–329.
doi: 10.1111/j.1600‐0501.2010.02003.x     

Fatigue resistance of yttria‐stabilized tetragonal zirconia polycrystal clasps for removable partial dentures

With the rapid development of computer‐aided design/computer‐aided manufacturing (CAD /CAM ) systems, the application of zirconia in removable partial dentures is expected to expand. Clasps composed of zirconia should improve esthetics without inducing the risk of metal allergy. The aim of this study was to examine the fatigue resistance of yttria‐stabilized tetragonal zirconia polycrystal (Y‐TZP) clasps for removable partial dentures. Yttria‐stabilized tetragonal zirconia polycrystal and cobalt‐chromium (Co‐Cr) alloy were prepared using CAD /CAM systems. Specimens were either of the semicircular type or of the flat type, with cross‐sectional areas of taper ratios of 0.50, 0.75, and 1.00. All specimens were tested using the cantilever test and the constant displacement fatigue test, and data were analyzed using ANOVA . During the cantilever test, the maximum displacement prior to fracture was greater than the required undercut, and the semicircular‐type specimen exhibited a higher fracture load than the flat type. None of the specimens displayed permanent deformation and showed almost the same degree of deformation after fatigue testing. A lower taper ratio was associated with lower average load values and greater displacement. Within the limitations of this study, it was possible to conclude that Y‐TZP provides the required undercut and adequate retentive force for removable partial denture clasps. Additionally, Y‐TZP and Co‐Cr alloy had almost the same degree of deformation even after the simulated lifespan of removable partial dentures.     

Effect of silica coating and laser treatment on the flexural strength,surface characteristics,and bond strength of a dental zirconia

This study investigated the effect of irradiation with an erbium‐doped yttrium aluminium garnet (Er:YAG) laser and coating with silica on the surface characteristics, bond strength, and flexural strength of dental zirconia. Three hundred and forty‐three standard zirconia specimens were created, and 49 were assigned to each of seven surface treatment groups: (i) no treatment; Er:YAG laser (80 mJ/2 Hz) with pulse widths of 50 μs (ii), 100 μs (iii), 300 μs (iv), or 600 μs (v); or tribochemical silica coating at the partially sintered stage (vi) or after sintering was complete (vii). All specimens were sintered after the surface treatments, except for the group in which specimens were sintered before treatment. The study outcomes were roughness, surface loss, microshear bond strength (μSBS), and biaxial flexural strength (BFS). Mean roughness and surface loss values were significantly higher in specimens from irradiated groups than in those from silica‐coated groups. Regarding μSBS, after aging, specimens from all experimental groups presented very low and similar μSBS values, irrespective of the surface treatment. Silica coating after sintering yielded the highest BFS (1149.5 ± 167.6 MPa), while coating partially sintered specimens with silica resulted a BFS (826.9 ± 60.9 MPa) similar to that of the untreated control group (794.9 ± 101.7 MPa). Laser treatments, irrespective of pulse width used, significantly decreased the BFS. In the group treated with laser at 300 μs pulse width, specimens exhibited the lowest BFS value (514.1 ± 71.5 MPa). Adhesion to zirconia was not stable after aging, regardless of the surface treatment implemented.