Effect of Ultrasonic Excitation on the Porosity of Glass Ionomer Cement: A Scanning Electron Microscope Evaluation

Background: Ultrasonic excitation (US) was applied to glass ionomer cement (GIC) during early set time to increase the advantageous properties of this material. Purpose: The aim of this in vitro study was to assess the inner porosity of GIC after US. Study design: A total of 16 specimens, for each material, were prepared from high-viscosity GIC Fuji IX GP, Ketac Molar, and Ketac Molar Easymix. Half of these specimens (n = 8) received 30 s of US during the initial cement setting. After completion of the material setting, specimens were fractured and observed by scanning electronic microscopy to quantitatively assay porosity inside the material using Image J software. Results: Statistical data analysis revealed that US reduced the porosity for all tested materials (P <= 0.05). The following reductions (expressed in percentages) were achieved: Fuji IX-from 3.9% to 2.8%; Ketac Molar Easy Mix-from 4.4% to 2.6%, and Ketac Molar-from 2.4% to 1.6%. Conclusion: Under the tested conditions, US was an effective method for porosity reduction inside the material. Microsc. Res. Tech. 74:54-57, 2011. (C) 2010 Wiley-Liss, Inc.

Influences of the insertion method in glass ionomer cement porosity

The aim of this study was to evaluate the presence of porosities inside the glass ionomer cement (GIC) after different techniques of material insertion. MATERIAL and METHOD: Specimens were prepared with high-viscosity GIC Ketac Molar Easymix and divided into three groups according to the insertion method: spatula (PI), Centrix injector (CI), and low-cost syringe (LCS). The specimens were fractured and observed with scanning electronic microscopy to quantitatively evaluate porosity inside the material using Image J Software. RESULTS: Statistical analysis, ANOVA application, and Tukey test to significance level of 5%, revealed that there was no statistical difference between the groups. CONCLUSION: Although the use of LCS has not decreased the porosity of the material, this insertion method is easy, accessible, and low cost, which makes it a viable alternative of use in the ART technique and in others bucal health programs. Microsc. Res. Tech., 2012. (c) 2012 Wiley Periodicals, Inc.

The Effect of Coating Patterns with Spinel-Based Investment on the Castability and Porosity of Titanium Cast into Three Phosphate-Bonded Investments

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Measurement of Interfacial Porosity at the Acrylic Resin/Denture Tooth Interface

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The occurrence of porosity in reline acrylic resins. Effect of microwave disinfection

Microwave energy has proved to be an effective method for disinfecting acrylic dentures. However, the effect of microwave heating on the porosity of autopolymerising denture reline resins has not been investigated.The purpose of the study was to determine the effect of microwave disinfection on the porosity of autopolymerised denture reline materials (Kooliner-K, New Truliner-NT, Tokuso Rebase Fast-TR and Ufi Gel Hard-UGH) and a conventional heat-polymerised denture base resin (Lucitone 550-L).Specimens (10 mm x 20 mm x 1 mm) were obtained from the impression surface of the palatal mucosa in a single person and divided into four groups (n = 5). The porosity was evaluated after polymerisation (C1), after two cycles of microwave disinfection (MW2), after seven cycles of microwave disinfection (MW7) and after 7 days storage in water at 37 degrees C (C2). Specimens from group MW7 were exposed to microwave disinfection daily being stored in water at 37 degrees C between exposures. All the replicas were sputter coated with gold and micrographs/digital images were taken of each replica using scanning electron microscopy at magnification x 100. The SEM micrographs were then examined using an image analyser to determine the number of pores. Comparison between materials and groups were made using Kruskal-Wallis tests.MW7 resulted in a significant increase in the number from the pores of material K, but decreased in number in reline material TR and UGH reline resin. The number of pores in materials NT and L remained unaffected following microwave disinfection.Differences in the porosity amongst the materials and for different experimental conditions were observed following microwave disinfection.

Reliability of a method for evaluating porosity in denture base resins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of synthesis and processing on supersaturated rare earth-doped nanometric SnO2 powders

This paper presents and discusses some of the results of the effects of processing on rare earth-doped nanosize SnO2. Several relevant factors that may influence the characteristics of the final product are studied. The influence of two preparation routes and two heat-treatment conditions on the incorporation of dopants is investigated. The route whereby a soluble salt is used as the dopant source is found to provide the highest degree of dopant incorporation, even under the least favorable heat-treatment conditions.

Characterization of the porosity developed in a new titania-alumina catalyst support prepared by the sol gel route

Titanium oxide (TiO2) is a good candidate for support of hydrotreating catalysts but has the disadvantage of presenting a low surface area and a poor thermal stability when compared with Al2O3. A mixed TiO2-Al2O3 support was proposed as an alternative that is expected to be free from these drawbacks. The variation during firing of the nanoporous texture of supports composed of TiO2-Al2O3, TiO2 and Al2O3 was studied by small angle X-ray scattering (SAXS). The supports were prepared by the sol-gel route using Ti and Al isopropoxides. We have particularly analyzed the effects of acid and basic hydrolysis on the nanostructural features of catalyst supports fired at different temperatures. The nanopore radius distribution functions were determined from SAXS results assuming a simple model of spherical nanopores embedded in a homogeneous solid matrix. The modal pore radius in both pure TiO2 and pure Al2O3 supports grows from 1.3 to 2.2 nm as the firing temperature increases from 673 to 973 K. on the other hand, the modal pore radius in the mixed TiO2-Al2O3 support remains below 1.2 nm over the same range of firing temperatures. These results demonstrate the good thermal stability of the nanoporous texture of mixed TiO2-Al2O3 supports.

The effect of polymerization cycles on porosity of microwave-processed denture base resin

Statement of problem. Although most of the physical properties of denture base resin polymerized by microwave energy have been shown to be similar to resins polymerized by the conventional heat polymerization method, the presence of porosity is a problem.Purpose. This study evaluated the effect of different microwave polymerization cycles on the porosity of a denture base resin designed for microwave polymerization.Material and methods. Thirty-two rectangular resin specimens (65 X 40 X 5 mm) were divided into 3 experimental groups (A, B, and C; Onda-Cryl, microwave-polymerized resin) and I control group (T; Classico, heat-polymerized resin), according to the following polymerization cycles: (A) 500 W for 3 minutes, (B) 90 W for 13 minutes + 500 W for 90 seconds, (C) 320 W for 3 minutes + 0 W for 4 minutes + 720 W for 3 minutes, and (T) 74degreesC for 9 hours. Porosity was calculated by measurement of the specimen volume before and after its immersion in water. Data were analyzed using 1-way analysis of variance (alpha = .05).Results. The mean values and SDs of the percent mean porosity were: A = 1.05% +/- 0.28%, B = 0.91% +/- 0.15%, C = 0.88% +/- 0.23%, T = 0.93% +/- 0.23%. No significant differences were found in mean porosity among the groups evaluated.Conclusion. Within the limitations of this study, a denture base resin specifically designed for microwave Polymerization tested was not affected by different polymerization cycles. Porosity was similar to the conventional heat-polymerized denture base resin tested.

Synthesis and photoluminescence study of La1.8Eu0.2O3 coating on nanometric alpha-Al2O3

In this work the La1.8Eu0.2O3 coating on nanometric alpha-alumina, alpha-Al2O3@La1.8Eu0.2O3, was prepared for the first time by a soft chemical method. The powder was heat-treated at 100, 400, 800 and 1200 degrees C for 2 h. X-ray powder diffraction patterns (XRD), transmission electronic microscopy (TEM), emission and excitation spectra, as well as Eu3+, lifetime were used to characterize the material and to follow the changes in structure as the heating temperature increases. The Eu3+ luminescence data revealed the characteristic transitions D-5(0) --> F-7(J) (J = 0, 1 and 3) of Eu3+ at around 580, 591 and 613 nm, respectively, when the powders were excited by 393 nm. The red color of the samples changed to yellow when the powder was annealed at 1200 degrees C. The decrease in the (D-5(0) --> F-7(2))/(D-5(0) --> F-7(1)) ratio from around 5.0 for samples heated at lower temperatures to 3.1 for samples annealed at 1200 degrees C is consistent with a higher symmetry of the Eu3+ at higher temperature. The excitation spectra of the samples also confirms this change by the presence of a more intense and broad band at around 317 nm, instead of the presence of the characteristic peak at 393 mn, which corresponds to the F-7(0) --> L-5(6) transition of the Eu3+. The lifetimes of the D-5(0) --> F-7(2) transition of Eu3+ for the samples heat-treated at 100, 400, 800 and 1200 degrees C was evaluated as 0.57, 0.72, 0.43 and 0.31 ms, respectively. (C) 2006 Elsevier Ltd. All fights reserved.