Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0-14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia. © 2013 Elsevier B.V. All rights reserved.

The impact of hydrofluoric acid etching followed by unfilled resin on the biaxial strength of a glass-ceramic

Objectives: To evaluate the null hypotheses that hydrofluoric (HF) acid etching time would neither decrease the biaxial flexural strength of a glass-based veneering ceramic nor enhance it after silane and unfilled resin (UR) applications. Methods: Disc-shaped IPS e.max ZirPress specimens were allocated into 12 groups: G1-control (no-etching), G2-30 s, G3-60 s, G4-90 s, G5-120 s, G6-60 s + 60 s. Groups (G7-G12) were treated in the same fashion as G1-G6, but followed by silane and UR applications. Surface morphology and roughness (Ra and Rq) of the ceramics were assessed by means of scanning electron microscopy (SEM) and profilometry, respectively. Flexural strength was determined by biaxial testing. Data were analyzed by two-way ANOVA and the Sidak test (α = 0.05). Weibull statistics were estimated and finite element analysis (FEA) was carried out to verify the stress concentration end areas of fracture. Results: The interaction (etching time vs. surface treatment) was significant for Ra (p = 0.008) and Rq (0.0075). Resin-treated groups presented significantly lower Ra and Rq than non-treated groups, except for the 60 s group (p < 0.005). SEM revealed that etching affected the ceramic microstructure and that the UR was able to penetrate into the irregularities. A significant effect of etching time (p = 0.029) on flexural strength was seen. G7-G12 presented higher strength than G1-G6 (p < 0.0001). None of experimental groups failed to show 95% confidence intervals of σ 0 and m overlapped. FEA showed lower stress concentration after resin treatment. Significance: HF acid etching time did not show a damaging effect on the ceramic flexural strength. Moreover, the flexural strength could be enhanced after UR treatment. © 2013 Academy of Dental Materials.

Influência do tratamento de superfície na adaptação externa de cavidade classe V hígida e afetada por cárie submetidas á ciclagem térmica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da cinética de cura e das propriedades térmicas da resina benzoxazina e de seus compósitos nanoestruturados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e caracterização de compósito processados por RTM para aplicação aeroespacial

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

Efeito da clorexidina e laser sobre a adaptação externa de resina a base de silorano em cavidade hígida e afetada por cárie

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação histopatológica do reparo apical e periapical em dentes de cães com vitalidade pulpar, após tratamento de canais radiculares utilizando dois cimentos obturadores à base de resina epóxica. Análise do pH e concentração de cálcio total

Pós-graduação em Odontologia - FOAR

Influência dos parâmetros de processamento por RTM no volume de vazios em compósitos carbono/epóxi

Pós-graduação em Engenharia Mecânica - FEG

Comparison of shear bond strength of orthodontics brackets on composite resin restorations with different surface treatments

INTRODUÇÃO: frequentemente, os pacientes ortodônticos apresentam restaurações de resina composta; no entanto, existem poucos estudos que avaliam a melhor forma de colagem ortodôntica nessa situação. OBJETIVO: o objetivo do presente trabalho foi avaliar a força adesiva de braquetes ortodônticos em restaurações resinosas com tratamento de superfície. MÉTODOS: foram utilizados 51 incisivos inferiores bovinos divididos aleatoriamente em três grupos. No grupo controle (GC), os braquetes foram colados em esmalte dentário; nos grupos experimentais com tratamento (GCT) e sem tratamento (GST), os braquetes foram colados em restauração de resina previamente realizada, diferenciando-se pelo tratamento de superfície com broca diamantada. Os dentes foram incluídos em tubos de PVC com resina acrílica autopolimerizável. O ensaio de cisalhamento foi executado em máquina universal de ensaios Emic. Os grupos foram submetidos à ANOVA com pós-teste de Tukey para verificação da diferença estatística entre os grupos (α = 0,05). RESULTADOS: GC (6,62MPa) e GCT (6,82MPa) apresentaram resultados semelhantes, enquanto o GST (5,07MPa) obteve resultados estatisticamente menores (p < 0,05). CONCLUSÃO: conclui-se que a melhor técnica de colagem de braquetes ortodônticos em restaurações de resina composta é a de realização de desgaste sobre a superfície.

Avaliação do comportamento de superfícies de fratura por fractais mistos em materiais de diferentes classes

Pós-graduação em Engenharia Mecânica - FEG

Healing Patterns After Subgingival Placement of a Resin-Modified Glass-Ionomer Restoration: A Histometric Study in Dogs

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Color Stability of Resin Used for Caries Infiltration After Exposure to Different Staining Solutions

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

Comparison of Physicochemical Surface Conditioning Methods for Adhesion of bis-GMA Resin Cement to Particulate Filler Composite and Surface Characterization

This study compared the effect of physicochemical surface conditioning methods on the adhesion of bis-GMA-based resin cement to particulate filler composite (PFC) used for indirect dental restorations. PFC blocks (N (block)=54, n (block)=9 per group) were polymerized and randomly subjected to one of the following surface conditioning methods: a) No conditioning (Control-C), b) Hydrofluoric acid (HF)etching for 60s (AE60), c) HF for 90s (AE90), d) HF for 120s (AE120), e) HF for 180s (AE180), and f) air-abrasion with 30 mu m silica-coated alumina particles (AB). The conditioned surfaces were silanized with an MPS silane, and an adhesive resin was applied. Resin composite blocks were bonded to PFC using resin cement and photo-polymerized. PFC-cement-resin composite blocks were cut under coolant water to obtain bar specimens (1mmx0.8mm). Microtensile bond strength test (mu TBS)was performed in a universal testing machine (1mm/min). After debonding, failure modes were classified using stereomicroscopy. Surface characterization was performed on a set of separate specimen surfaces using Scanning Electron Microscopy (SEM), X-Ray Dispersive Spectroscopy (XDS), X-Ray Photoelectron Spectroscopy (XPS), and Fourier Transform-Raman Spectroscopy (FT-RS). Mean mu TBS (MPa) of C (35.6 +/- 4.9) was significantly lower than those of other groups (40.2 +/- 5.6-47.4 +/- 6.1) (p<0.05). The highest mu TBS was obtained in Group AB (47.4 +/- 6.1). Prolonged duration of HF etching increased the results (AE180: 41.9 +/- 7), but was not significantly different than that of AB (p>0.05). Failure types were predominantly cohesive in PFC (34 out of 54) followed by cohesive failure in the cement (16 out of 54). Degree of conversion (DC) of the PFC was 63 +/- 10%. SEM analysis showed increased irregularities on PFC surfaces with the increased etching time. Chemical surface analyses with XPS and FT-RS indicated 11-70% silane on the PFC surfaces that contributed to improved bond strength compared to Group C that presented 5% silane, which seemed to be a threshold. Group AB displayed 83% SiO2 and 17% silane on the surfaces.

Free radical entrapment and crystallinity of resin composites after accelerated aging as a function of the expiration date

This study evaluated the spin concentration and the crystallinity in different classifications of dental composites as a function of the material condition (new, aged and expired). Specimens were obtained according to the factors: composites: Filtek P60, Filtek Z250, Filtek Z350XT, and Filtek Silorane; and material conditions: new, aged, and expired. The syringe composites underwent an accelerated aging protocol (Arrhenius model). The magnetic properties of the composites were characterized using Electron Paramagnetic Resonance (EPR) and the concentration of spins (number of spins/mass) was calculated. The crystallinity of the composites tested was characterized with X-ray diffraction (XRD). Filtek P60 and Filtek Z250 presented similarities in terms of spin concentration and crystallinity, irrespective of the material condition. The aging protocol influenced the composite Filmic Z350XT that exhibited a significant increase in the spin concentration. Besides, lower intensity peaks of the organic matrix and amorphous silica were also observed for both aged and expired Filtek Z350XT. Although a significant lower spin concentration was observed for the silorane composite in comparison to that of the methacrylates, a decrease in the relative intensity of peaks of the amorphous region related to the organic components in the diffractograms was observed. The material conditions tested influence the crystallinity and the magnetic properties of the composites evaluated. (C) 2014 Elsevier Ltd. All rights reserved.

Resin composite characterizations following a simplified protocol of accelerated aging as a function of the expiration date

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)