Long-term surface hardness and monomer conversion of a nonofilled and a microhybrid composite resin

Objective: This study aims to evaluate the degree of conversion (DC) and hydrolytic degradation through the Vickers hardness test (HV) of a nanofilled (Filtek��� Z-250, 3M) and a microhybrid (Filtek���Supreme-XT, 3M) composite resin. Materials and methods: Eight disk-shaped specimens (4 mm diameter �� 2 mm thick, ISO 4049) of each material were prepared for each test. Composites were inserted into single increment in a metallic matrix and light-cured for 40 seconds. VH readings were performed for each specimen at predetermined intervals: immediately after polymerization (control), 1, 2, 3, 7, 14, 21, 30 and 180 days. After curing, initial hardness measurements were performed and the specimens were immersed in artificial saliva at 37��C. For DC (%), specimens were ground, pressed with KBr and analyzed by FT-IR spectrophotometer. Results: Student t-test showed that there was no difference between the resins for DC (p = 0.252). ANOVA analysis revealed that Z-250 VH means were all greater than S-XT, for both top and bottom surfaces, whatever the storage-period in artificial saliva (p < 0.001). After 180 days of storage, the hardness obtained for S-XT was similar with that at the baseline, for both top and bottom surfaces. While for Z-250 hardness was not significantly different from baseline only for top surface, but there was a significant decrease observed in hardness for bottom surface. Conclusion: The materials tested showed no evidence of hydrolytic degradation in a significant way, in a 6-month storagetime in artificial saliva. Nanofilled resin presents a monomer conversion comparable to the conventional microhybrid.

Influence of light source and immersion media in surface roughness and hardness of a nanofilled composite resin

The study evaluated the influence of light curing units and immersion media on superficial roughness and microhardness of the nanofilled composite resin Supreme XT (3M/ESPE). Light curing units used were: XL 3000 (3M/ESPE), Jet Lite 4000 Plus (JMorita) and Ultralume Led 5 (Ultradent) and immersion media were artificial saliva, Coke��, tea and coffee, totaling 12 experimental groups. Specimens (10mm x 2mm) were immersed in each respective solution for 5 seconds, three times a day, during 60 days and so, were submitted to measure of superficial roughness (Ra) and Vickers hardness. Data were subjected to two-way ANOVA test (p<0.05). Results showed that only the light source factor showed statistically difference for hardness. It was observed that the hardness of the composite resin Filtek Supreme XT (3M/ESPE) was influenced by the light source (p<0.01) independently of the immersion media (p= 0.35) and the Jet Lite 4000 Plus (JMorita) was the light curing unit that presented lower values. In relation to surface roughness, it was noted no-significant statistical difference for light source (p=0.84), when specimens were immersed in different beverages (p=0.35).

Surface roughness and hardness of yttria stabilized zirconia (Y-TZP) after 10 years of simulated brushing

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Addition of Chlorhexidine Gluconate to a Glass Ionomer Cement: A Study on Mechanical, Physical and Antibacterial Properties

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Efeito de elementos susbstitucionais e intersticiais nas propriedades mec��nicas e na biocompatibilidade de ligas do sistema Ti-15Zr-xMo

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Influ��ncia da espessura da infraestrutura em Zirc��nia (3Y-TZP)na resist��ncia mec��nica da porcelana de cobertura

P��s-gradua����o em Reabilita����o Oral - FOAR

Surface degradation of lithium disilicate ceramic after immersion in acid and fluoride solutions

Purpose: To analyze whether immersion in sodium fluoride (NaF) solutions and/or common acidic beverages (test solutions) would affect the surface roughness or topography of lithium disilicate ceramic. Methods: 220 ceramic discs were divided into four groups, each of which was subdivided into five subgroups (n = 11). Control group discs were immersed in one of four test beverages for 4 hours daily or in artificial saliva for 21 days. Discs in the experimental groups were continuously immersed in 0.05% NaF, 0.2% NaF, or 1.23% acidulated phosphate fluoride (APF) gel for 12, 73, and 48 hours, respectively, followed by immersion in one of the four test beverages or artificial saliva. Vickers microhardness, surface roughness, scanning electron microscopy (SEM) associated with energy dispersive spectroscopy, and atomic force microscopy (AFM) assessments were made. Data were analyzed by nested analysis of variance (ANOVA) and Tukey&apos;s test (alpha = 0.05). Results: Immersion in the test solutions diminished the microhardness and increased the surface roughness of the discs. The test beverages promoted a significant reduction in the Vickers microhardness in the 0.05% and 0.2% NaF groups. The highest surface roughness results were observed in the 0.2% NaF and 1.23% APF groups, with similar findings by SEM and AFM. Acidic beverages affected the surface topography of lithium disilicate ceramic. Fluoride treatments may render the ceramic surface more susceptible to the chelating effect of acidic solutions.

Characterization of a wollastonite glass-ceramic material prepared using sugar cane bagasse ash (SCBA) as one of the raw materials

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

A comparison of microhardness of indirect composite restorative materials

The purpose of this study was to compare the microhardness of four indirect composite resins. Forty cylindrical samples were prepared according to the manufacturer s recommendations using a Teflon mold. Ten specimens were produced from each tested material, constituting four groups (n=10) as follows: G1 - Artglass; G2 - Sinfony; G3 - Solidex; G4 - Targis. Microhardness was determined by the Vickers indentation technique with a load of 300g for 10 seconds. Four indentations were made on each sample, determining the mean microhardness values for each specimen. Descriptive statistics data for the experimental conditions were: G1 - Artglass (mean �����standard deviation: 55.26 �� 1.15HVN; median: 52.6); G2 - Sinfony (31.22 �� 0.65HVN; 31.30); G3 - Solidex (52.25 �� 1.55HVN; 52.60); G4 - Targis (72.14 �� 2.82HVN; 73.30). An exploratory data analysis was performed to determine the most appropriate statistical test through: (I) Levene's for homogeneity of variances; (II) ANOVA on ranks (Kruskal-Wallis); (III) Dunn's multiple comparison test (0.05). Targis presented the highest microhardness values while Sinfony presented the lowest. Artglass and Solidex were found as intermediate materials. These results indicate that distinct mechanical properties may be observed at specific materials. The composition of each material as well as variations on polymerization methods are possibly responsibles for the difference found in microhardness. Therefore, indirect composite resin materials that guarantee both good esthetics and adequate mechanical properties may be considered as substitutes of natural teeth.

Analysis of residual stress and hardness in regions of pre-manufactured and manual bends in fixation plates for maxillary advancement

The aim of this study was to analyze, through Vickers hardness test and photoelasticity analysis, pre-bent areas, manually bent areas, and areas without bends of 10-mm advancement pre-bent titanium plates (Leibinger system). The work was divided into three groups: group I-region without bend, group II-region of 90�� manual bend, and group III-region of 90�� pre-fabricated bends. All the materials were evaluated through hardness analysis by the Vickers hardness test, stress analysis by residual images obtained in a polariscope, and photoelastic analysis by reflection during the manual bending. The data obtained from the hardness tests were statistically analyzed using ANOVA and Tukey's tests at a significance level of 5��%. The pre-bent plate (group III) showed hardness means statistically significantly higher (P���<���0.05) than those of the other groups (I-region without bends, II-90�� manually bent region). Through the study of photoelastic reflection, it was possible to identify that the stress gradually increased, reaching a pink color (1.81 �����/�����), as the bending was performed. A general analysis of the results showed that the bent plate region of pre-bent titanium presented the best results.

Caracteriza����o de juntas soldadas em PAW e GTAW de chapas finas em a��o maraging 300 submetidas a v��rios reparos

P��s-gradua����o em Engenharia Mec��nica - FEG

Structure, microstructure, and selected mechanical properties of Ti-Zr-Mo alloys for biomedical applications

New titanium alloys for biomedical applications have been developed primarily with the addition of Nb, Ta, Mo, and Zr, because those elements stabilize the �� phase and they don���t cause cytotoxicity in the organism. The objective of this paper is to analyze the effect of molybdenum on the structure, microstructure, and selected mechanical properties of Ti-15Zr-xMo (x = 5, 10, 15, and 20 wt%) alloys. The samples were produced in an arc-melting furnace with inert argon atmosphere, and they were hot-rolled and homogenized. The samples were characterized using chemical, structural, and microstructural analysis. The mechanical analysis was made using Vickers microhardness and Young���s modulus measurements. The compositions of the alloys were sensitive to the molybdenum concentration, indicating the presence of �����+�����+�� phases in the Ti-15Zr-5Mo alloy, �����+�� in the Ti-15Zr-10Mo alloy, and �� phase in the Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys. The mechanical properties showed favorable values for biomedical application in the alloys presenting high hardness and low Young���s modulus compared with CP-Ti.

Effect of the substitutional elements on the microstructure of the Ti-15Mo-Zr and Ti-15Zr-Mo systems alloys

Titanium alloys have excellent biocompatibility, and combined with their low elastic modulus, become more efficient when applied in orthopedic prostheses. Samples of Ti-15Mo-Zr and Ti-15Zr-Mo system alloys were prepared using an arc-melting furnace with argon atmosphere. The chemical quantitative analysis was performed using an optical emission spectrometer with inductively coupled plasma and thermal conductivity difference. The X-ray diffractograms, allied with optical microscopy, revealed the structure and microstructure of the samples. The mechanical analysis was evaluated by Vickers microhardness measurements. The structure and microstructure of alloys were sensitive to molybdenum and zirconium concentration, presenting �����, ����� and �� phases. Molybdenum proved to have greater ��-stabilizer action than zirconium. Microhardness was changed with addition of molybdenum and zirconium, having Ti-15Zr-10Mo (436 �� 2 HV) and Ti-15Mo-10Zr (378 �� 4 HV) the highest values in each system.

Influ��ncia do aporte t��rmico da soldagem GTAW no balan��o de fases Ferrita/Austenita do A��o Inoxid��vel Duplex UNS S32205

P��s-gradua����o em Engenharia Mec��nica - FEIS

Incorpora����o de nanopart��culas de ��xido de zinco a um cimento de ion��mero de vidro por meio da calcina����o: avalia����o de propriedades mec��nicas e f��sicas

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)