PMMA/HA-GF医用复合材料制备及性能测试

本文主要研究了无机玻璃纤维增强聚甲基丙烯酸甲酯(PMMA)/羟基磷灰石(HA)复合材料的制备及相关的性能测试,证明此复合材料性能稳定、物理机械强度高以及工艺简单,有良好的应用前景。     

Radiologic long-term results after cervical vertebral interbody fusion with Polymethyl Methacrylat (PMMA)

Long-term results of cervical interbody fusion with PMMA were evaluated in a retrospective study. X-ray films of 83 patients were obtainable. Post-operative follow-up in this series was between 15 and 20 years. The results show that PMMA is engrafted after about 2 years. Stable vertebral interbody fusion is obtained in about 90% of cases. Development of malignoma was not observed. Resorptive bone alterations, which can be seen in about 2% of cases one to two years after operation are shown not to be progressive. This process heals and stable fusion develops.     

Purification of bovine conglutinin using pepsin digestion

This paper describes a new method for the purification of bovine conglutinin based on the relative resistance of this protein to pepsin digestion. First, conglutinin is purified by absorption on yeast, then the preparation is treated with 2% pepsin (w/w) at 4°C for 18 hr, and finally gel filtrated on agarose A5m. The yield is 60–75% and conglutinin thus prepared appears physically, immunochemically and functionally intact. This procedure allows for a rapid production of sufficient amounts of conglutinin for immune complex detection or purification methods.     

A Novel Macroinitiator for the Synthesis of Triblock Copolymers via Atom Transfer Radical Polymerization: Polystyrene‐block‐poly(bisphenol A carbonate)‐block‐polystyrene and Poly(methyl methacrylate)‐block‐poly(bisphenol A carbonate)‐block‐poly(methyl methacrylate)

Summary: Bis(hydroxy)telechelic bisphenol A polycarbonate (PC) was prepared via melt polycondensation of bisphenol A (BPA) and diphenyl carbonate (DPC) using lanthanum(III ) acetylacetonate as a catalyst for transesterification. Subsequently, the polycarbonate was converted to a bifunctional macroinitiator for atom transfer radical polymerization (ATRP) with the reagent, α‐chlorophenylacetyl chloride. The macroinitiator was used for the polymerization of styrene (S) and methyl methacrylate (MMA) to give PS‐block‐PC‐block‐PS and PMMA‐block‐PC‐block‐PMMA triblock copolymers. These block copolymers were characterized by NMR and GPC. When styrene and methyl methacrylate were used in large excess, significant shifts toward high molecular weights were observed with quantitative consumption of the macroinitiator. Several ligands were studied in combination with CuCl as the ATRP catalyst. Kinetic studies reveal the controlled nature of the polymerization reaction for all the ligands used.

Formation of a bifunctional ATRP macroinitiator by esterification of bis(hydroxy)telechelic PC with α‐chlorophenylacetyl chloride.     

氟—肝素表面修饰人工晶状体植入兔眼后眼前段病理改变

目的 研究氟－肝素表面修饰人工晶状体植入后眼前段组织病理改变,了解其生物相容性。方法 将氟－肝素表面修饰人工晶状体及ＰＭＡＭ人工晶状体各３２枚分别植入兔眼后房３月。术后不同时间摘除眼球,取眼前段做组织病理切片,光镜观察。结果 两种人工晶状体植入后,兔眼前段组织病理变化无明显区别。但９０天时,修饰晶状体组睫状体非色素上皮细胞水样变性较轻,间质组织增生较少,结论 氟－肝素表面修饰人工晶状体略有较好的生     

注入式义眼台技术的动物实验观察

目的：观察应用骨水泥注入巩膜腔形成义眼台对兔眼组织的影响。方法：依据处死的时间将15只新西兰大白兔分作5组，每兔一眼做实验用眼．另眼为对照，手术时用手指挤压和碘伏棉签清除兔眼内容物和色素组织后注入骨水泥，进行肉眼观察、测量眼球重量并进行统计学处理，而后行病理组织学检查。结果：术后实验和对照眼球重量无明显差异，组织学显示术后早期组反应呈现为炎性坏死反应，大量炎性细胞浸润；而后呈现为炎性坏死反应向纤维组织增生过度；术后3个月呈现为眼角膜血管化，围绕义眼台形成纤维膜，炎性反应基本消失。结论：聚甲基丙烯酸甲酯义眼台有良好的生物相容性，比重适当，注入式义眼台技术手术操作相对简单，术后义眼活动度良好，具有应用价值。     

Comparison of wear between occlusal splint materials and resin composite materials

Tooth wear in bruxing patients often results in a need for treatment with composite restorations. In some cases, bruxing patients receive an occlusal splint as a protective means as well. However, the wear between these opposing materials has not been investigated yet. The aim of this in vitro study was to assess the wear of different splint materials against resin composite materials. A two‐body wear test was conducted using the ACTA wear machine. The materials selected for this study were three composites used for direct restorations (Filtek Z250, CLEARFIL AP‐X, and Filtek Supreme XT) and four occlusal splints materials, viz. a polyamide resin (ThermoSens) an conventional (hand‐processed), milled and printed polymethylmethacrylate (PMMA). As antagonistic materials, stainless steel, Filtek Supreme XT and CLEARFIL AP‐X were used. The wear rate of the seven materials was determined after 200 000 cycles, using a profilometry. The rates were analysed using two‐way ANOVA and post hoc Tukey's tests. The wear rates were significantly higher for the conventional and milled PMMA materials than for all other materials (P < .001). The wear rates of printed PMMA and the polyamide resin were comparable to composite wear rates. The antagonist materials have minor or no influence on the amount of wear of the various splint materials (P < .001). In conclusion, different splint materials yielded different wear rates for all antagonist materials tested. Keeping in mind that this study is an experimental in vitro study, this finding enables practitioners to choose the splint material necessary according to their patients’ needs.     

A Toluidine Blue Method for Demonstrating Mast Cells

Abstract

A modified Giemsa azure-eosin method for staining polymethyl methacrylate (PMMA) plastic embedded bone sections is described. The method is similar to those used to stain glycol methacrylate sections but differs in timing and addition of air drying steps. The stain yields effective differentiation of marrow cells, growth plate, calcified cartilage, osteoid, bone matrix and bone cells in undecalcified sections of bone. The stain does not interfere with the resolution of fluorochrome labeled specimens. Hence, the same slide can beused to evaluate static and dynamic parameters of bone metabolism. (The J Histotechnol 14:85, 1991)     

Concentration Fluctuations and Segmental Dynamics in Weakly Dynamic Asymmetric Blends in the Presence of Surface‐Functionalized Multiwall Carbon Nanotubes

Surface‐functionalized multiwall carbon nanotubes (MWCNTs) are incorporated in poly(methyl methacrylate)/styrene acrylonitrile (PMMA/SAN) blends and the pretransitional regime is monitored in situ by melt rheology and dielectric spectroscopy. As the blends exhibit weak dynamic asymmetry, the obvious transitions in the melt rheology due to thermal concentration fluctuations are weak. This is further supported by the weak temperature dependence of the correlation length (ξ ≈ 10–12 Å) in the vicinity of demixing. Hence, various rheological techniques in both the temperature and frequency domains are adopted to evaluate the demixing temperature. The spinodal decomposition temperature is manifested in an increase in the miscibility gap in the presence of MWCNTs. Furthermore, MWCNTs lead to a significant slowdown of the segmental dynamics in the blends. Thermally induced phase separation in the PMMA/SAN blends lead to selective localization of MWCNTs in the PMMA phase. This further manifests itself in a significant increase in the melt conductivity.

     

Discoloration of Provisional Restorations after Oral Rinses

Purpose: Oral rinses are widely used to promote periodontal health with provisional restorations during the interim period. The aim of this study was to compare the discoloration of provisional restoration materials with different oral rinses.Material and Methods: A total of 140 disc-shaped specimens (shade A2) (10 mm x 2 mm) were prepared from one PMMA-based (TemDent Classic^®) and three different bis-acrylic-based (Protemp II^®, Luxatemp^® and Fill-In^®) provisional restoration materials (n=7). The color values (L*, a*, and b*) of each specimen were measured before and after exposure with a colorimeter, and the color changes (∆E) were calculated according to the CIE L*a*b* system. The specimens were immersed in each of the 4 oral rinses (alcohol-containing mouthwash, chlorhexidine, benzydamine HCl, benzydamine HCl and chlorhexidine) twice a day for 2 minutes. After 2 minutes of immersion in the oral rinses, the specimens were immersed in artificial saliva. The specimens were exposed to the oral rinses and the artificial saliva for 3 weeks. Two-way ANOVA, the Bonferroni test and the paired sample t-test were used for statistical analyses (p<0.05).Results: Comparison of the discoloration from the oral rinses after immersion for three weeks revealed no significant differences (p>0.05). The lowest color change was observed in PMMA-based Temdent in all oral rinses (p<0.05). There were no significant differences between the bis-acryl composites after immersion in saliva or the mixture of benzydamine HCl and chlorhexidine and the alcohol-containing mouthwash for 3 weeks (p>0.05). After immersion in chlorhexidine, the color change values of Protemp II and Fill-in showed significant differences (p=0.018). Protemp II also showed less discoloration than the other bis-acryl composites, and this color change was statistically significant (p <0.05). For all oral rinses, the L* value decreased while b* values increased, and this color change was found to be statistically significant (p <0.05). A* values were found to be significantly higher with oral rinses (p<0.05), except Protemp II immersed in benzydamine HCl or alcohol-containing mouthwash.Conclusions: The type of the oral rinse did not affect the discoloration process. For long-term esthetic results, choosing MMA-based materials for provisional restorations appears to be more effective.