Navegação por Revista "Dental Materials"

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  • IPEN-DOC 16091

    BOTTINO, M.C.; VALANDRO, L.F.; AMARAL, R.; BOTTINO, M.A.; OZCAN, M.; USSUI, V. ; BRESSIANI, A.H.A. ; LAZAR, D.R.R. . Adhesive durability of phosphate monomer resin cement to Y-TZP ceramic. Dental Materials, v. 26, p. e149, 2010.

    Palavras-Chave: ceramics; zirconium oxides; yttrium oxides; coprecipitation; mechanical properties; adhesives; monomers

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  • IPEN-DOC 17286

    MONTEIRO, GABRIELA Q.M.; MONTES, MARCOS A.J.R.; ROLIM, TIAGO V.; MOTA, CLAUDIA C.B. de O.; KYOTOKU, BERNARDO de B.C.; GOMES, ANDERSON S.L.; FREITAS, ANDERSON Z. de . Alternative methods for determining shrinkage in restorative resin composites. Dental Materials, v. 27, n. 8, p. e176-e185, 2011.

    Palavras-Chave: dentistry; composite materials; caries; repair; resins; polymerization; shrinkage; coherent radiation; coordinates; measuring instruments; teeth; tomography; optical models

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  • IPEN-DOC 24964

    SILVA, L.T.S.; COGO-MULLER, K.; BRANDT, W.C.; CAMPOS, L.M.P. ; PARRA, D.F. ; SANTOS, M.; BOARO, L.C.C.. Antibacterial activity of endodontic sealer modified with nanoparticles. Dental Materials, v. 33, suppl. 1, p. e13-e13, 2017. DOI: 10.1016/j.dental.2017.08.022

    Abstract: Purpose/aim: The aim of this study was to evaluate the antibacterial activity of a commercial endodontic sealer modified with montmorillonite nanoparticles carrying to different drugs: clorhexidine (CHX) and metronidazole (MET). Materials and methods: The sealer used was AH Plus sealer, and 5% in weight was added of the nanoparticles carrying one of the drugs CHX or MET. Cylindrical specimens were made with 5 mm diameter and 1 mm thick (n = 5). The antibacterial activity was evaluated by the inhibition halo test. This method was conducted according to Clinical Standard Laboratory Institute M2-A8 protocol, with some modifications (CLSI, 2003). The bacteria selected were the E. Fecallis which is the most frequently bacteria found in recidivate apical infection. Discs specimens were positioned over the agar and plates were incubated in the appropriate conditions for 48 h. After this period, inhibition zones were measured using a calliper rule. A group with no modification by the nanoparticle was added as a control. The data was analyzed using Mann–Whitney (alpha = 5%). Results: Results are presented in Table 1. For the control group no inhibition zone was formed, so the statistical analyze was performed only between the experimental groups. Table 1. Means (SD) for inhibition halo (mm). No statistical difference was presented between the drugs. Drug Inhibition halo (mm) Control 0 CHX 4.8 (1.4) A MET 4.0 (1.6) A Conclusions: Within the limitations of this study it can be concluded that the addition of the nanoparticle carrying both drugs added an antibacterial activity that was not found in the commercial sealer.

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  • IPEN-DOC 25707

    BOARO, LETICIA C.C. ; CAMPOS, LUIZA M. ; VARCA, GUSTAVO H.C. ; SANTOS, TAMIRIS M.R. dos ; MARQUES, PAMELA A.; SUGII, MARI M.; SALDANHA, NATHALIA R.; COGO-MULLER, KARINA; BRANDT, WILLIAM C.; BRAGA, ROBERTO R.; PARRA, DUCLERC F. . Antibacterial resin-based composite containing chlorhexidine for dental applications. Dental Materials, v. 35, n. 6, p. 909-918, 2019. DOI: 10.1016/j.dental.2019.03.004

    Abstract: Objeticve. The aim of this study was to develop a composite material with antibacterial activ-ity using MMT loaded with clorhexidine (CHX). For that it was used a BisGMA/TEGDMAmatrix and added low concentration of MMT/CHX. The aim was to evaluate the drug releasecapacity of MMT, and not to provide reinforcement.Methods. Six experimental composites were made with organic matrix of BisGMA/TEGDMAin equal proportions by weight. The composites received organophlizated montmorillonitewith or without CHX. The concentrations were 2,5; 5 or 10% by weight. Degree of conversion(DC) was evaluated using FTIR (peak 6165 cm-1; n = 5). Specimens for flexural properties(10×2×1 mm) were immediate tested (24h). Elastic modulus(E) and flexural strength (FS)was measured using the three point bending test (n = 10). Inibition halo was used to test theantibacterial activity against Staphylococcus aureus, Streptococcus mutans, and Porphyromonasgingivalis (n = 5 for each bacteria). The inhibition of biofilm formation (BF) was evaluated byinserting polymerized disc of composite in to a culture media colonized with Streptococcusmutans (n = 10). The release of CHX was measured using ultraviolet (255 nm) for 10 days(n = 5). The data of degree of conversion was analysed using Kruskal–Wallis/ Mann–Whitney,and the other variables using two-way ANOVA/Tukey, always considering a global level ofsignificance of 5%.Results. DC ranged from 71% to 74%. E ranged from 5.7 to 8.1 GPa. FS ranged from 61.4 to74.7 MPa. There were no statistical differences among the groups for all the variables. Forthe three bacteria tested the composites with CHX loaded presented inhibition of growthfor all concentration, except for 2,5% that did not inihibited the growth of P. gingivalis. BFwas lower for the groups with 10% MMT/CHX, all groups presented BF, even those withoutCHX loaded. All concentrations presented release off CHX during all the 28 days analyzed. Conclusions. Within the limitation of this study it can be concluded that: all concentrations tested presented release of CHX and reduced BF. All concentration presented antibacterial activity for the three bacteria tested, except for 2,5% that did not inhibit the growth of P. gingivalis. The presence of MMT with CHX loaded did not interfere in the properties evaluated.

    Palavras-Chave: composite materials; germicides; dentistry; manganese compounds; chlorine compounds; bacteria; staphylococcus; streptococcus; antimicrobial agents; resins

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  • IPEN-DOC 22772

    ALANIA, YVETTE; CHIARI, MARINA D.S.; RODRIGUES, MARCELA C.; ARANA-CHAVEZ, VICTOR E.; BRESSIANI, ANA H.A. ; VICHI, FLAVIO M.; BRAGA, ROBERTO R.. Bioactive composites containing TEGDMA-functionalized calcium phosphate particles: Degree of conversion, fracture strengthand ion release evaluation. Dental Materials, v. 32, p. e374-e381, 2016. DOI: 10.1016/j.dental.2016.09.021 Orientador: COMPOSITE MATERIALS.

    Abstract: Objective. To evaluate the strength and ion release of experimental composites containingTEGDMA-functionalized calcium phosphate particles.Methods. Seven composites containing equal parts (in mols) of BisGMA and TEGDMA and60 vol% of fillers were manipulated. Filler phase was constituted by silanized barium glassand 0% (control), 10% or 20% (volume) of dicalcium phosphate dihydrate (DPCD) particles,either non-functionalized or functionalized with two different TEDGMA contents. DCPDparticles were synthesized and characterized by X-ray diffraction (XRD), elemental analysis,surface area and dynamic light scattering. Composites were tested for degree of conversion(DC) by near-FTIR. Biaxial flexural strength (BFS) was determined after 24 h and 28 days inwater. Calcium and phosphate release after 7 days was assessed using inductively coupledplasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey test(alpha:5%).Results. XRD confirmed the crystalline structure corresponding to DCPD. Elemental analysisrevealed particles with zero, 14% or 22% TEGDMA, with similar D50(around 19 m) andsurface areas from 3.5 to 11.4 m2/g. The presence of DCPD did not reduce DC. After 24 h,functionalization (both 14% and 22% TEGDMA) improved composite strength in comparisonto non-functionalized DCPD, both at 10% and 20% levels. After 28 days, BFS of materialscontaining 10% functionalized DCPD were statistically similar to the control containing onlybarium glass. Among composites containing 10% DCPD, particle functionalization with 14%TEGDMA did not jeopardize ion release.

    Palavras-Chave: methacrylates; calcium phosphates; mechanical properties; resins; composite materials; x-ray diffraction; surface area; light scattering; spectroscopy

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  • IPEN-DOC 23686

    BOARO, L.; CAMPOS, L.M. ; VARCA, G.H.C. ; MARQUES, P.A.; PIMENTEL, A.C.; ROMAN-TORRES, C.V.; BRANDT, W.C.; COGO-MULLER, K.; BRAGA, R.R.; PARRA, D.F. . BisGMA/TEGDMA based material with antibacterial activity. Dental Materials, v. 32, suppl. 1, p. e8-e9, 2016. DOI: 10.1016/j.dental.2016.08.016

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  • IPEN-DOC 24966

    SANCHES, L.K.F.; CAMPOS, L.M.P. ; PARRA, D.F. ; BRAGA, R.R.; SANTOS, M.; BOARO, L.C.C.. Conversion of endodontic sealer modified with nanoparticles carrying antibacterial drugs. Dental Materials, v. 33, suppl. 1, p. e70-e70, 2017. DOI: 10.1016/j.dental.2017.08.140

    Abstract: Purpose/aim: The aim of this study was to evaluate the polymeric conversion of a commercial endodontic sealer modified with montmorillonite nanoparticles carrying to different antibacterial drugs: clorhexidine (CHX) and metronidazole (MET). Materials and methods: The sealer used was AH Plus sealer, and 5% in weight was added of the nanoparticles carrying one of the drugs CHX or MET. Cylindrical specimens were made with 5 mm diameter and 1 mm thick (n = 5). The degree of conversion (DC) was determined using near FTIR. DC was evaluated using the absorption peak at 4529 cm−1 that decrease during polymerization, and the absorption peak at 4623 cm−1 which is unaltered as normalization. The measurements were obtained for each sample immediately, 4 h and 24 h after mixing the two pastes of the sealer. A group with no modification by the nanoparticle was added as a control. The data was analyzed using one-way ANOVA/Tukey (α = 5%). Results: Results are presented in Table 1. Table 1. Means (SD) for degree of conversion (%) at 4 and 24 h. No statistical difference was presented among groups for neither periods of evaluation. Drug DC (%) 4 h 24 h Control 35 (11) A 68 (8) A CHX 31 (11) A 81 (11) A MET 38 (6) A 77 (14) A Conclusions: Within the limitations of this study it can be concluded that addition of the nanoparticle carrying both drug did not influence the polymerization of the sealer.

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  • IPEN-DOC 23687

    MONTEIRO, K.N.; CORREIA, Y.P.; GENOVA, L.A. ; CESAR, P.F.. Effect of shade and ageing on strength of translucent Y-TZP. Dental Materials, v. 32, suppl. 1, p. e9-e10, 2016. DOI: 10.1016/j.dental.2016.08.019

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  • IPEN-DOC 24121

    MIRANDA, RANULFO B. de P.; MIRANDA JUNIOR, WALTER G.; LAZAR, DOLORES R.R. ; USSUI, VALTER ; MARCHI, JULIANA; CESAR, PAULO F.. Effect of titania content and biomimetic coating onthe mechanical properties of the Y-TZP/TiO2 composite. Dental Materials, v. 34, n. 2, p. 238-245, 2018. DOI: 10.1016/j.dental.2017.11.003

    Abstract: Objectives. During the last decades, several changes of paradigm have modified our view on how biomaterials' surface characteristics influence the bioresponse. After becoming aware of the role of a certain microroughness for improved cellular contact and osseointegration of dental titanium implants, the likewise important role of surface energy and wettability was increasingly strengthened. Very recently, synergistic effects of nanoscaled topographical features and hydrophilicity at the implant/bone interface have been reported. Methods. Questions arise about which surface roughness and wetting data are capable to predict the bioresponse and, ultimately, the clinical performance. Current methods and approaches applied for topographical, wetting and surface energetic analyses are highlighted. Current knowledge of possible mechanisms explaining the influence of roughness and hydrophilicity at the biological interface is presented. Results. Most marketed and experimental surfaces are based on commonly available additive or subtractive surface modifying methods such as blasting, etching or anodizing. Different height, spatial, hybrid and functional roughness parameters have been identified as possible candidates able to predict the outcome at hard and soft tissue interfaces. Likewise, hydrophilic implants have been proven to improve the initial blood contact, to support the wound healing and thereby accelerating the osseointegration. Significance. There is clear relevance for the influence of topographical and wetting characteristics on a macromolecular and cellular level at endosseous implant/biosystem interfaces. However, we are still far away from designing sophisticated implant surfaces with the best possible, selective functionality for each specific tissue or cavity interface. Firstly, because our knowledge of the respective surface related reactions is at best fragmentary. Secondly, because manufacturing of multi-scaled complex surfaces including distinct nanotopographies, wetting properties, and stable cleanliness is still a technical challenge and far away from being reproducibly transferred to implant surfaces. (C) 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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  • IPEN-DOC 24250

    SILVA, L.H.; LAZAR, D.R.R. ; USSUI, V. ; YOSHITO, W.K. ; TANGO, R.N.; BELLI, R.; LOHBAUER, U.; CESAR, P.F.. Fatigue limit of Y-TZP reinforced with carbon nanotubes. Dental Materials, v. 33, suppl. 1, p. e19-e19, 2017. DOI: 10.1016/j.dental.2017.08.036

    Abstract: Purpose/aim: To compare the Cyclic Fatigue Limit (CFL) of a control yttria-stabilized tetragonal zirconia pollycristal (Y-TZP) with a composite produced by adding multi-walled carbon nanotubes (CNT) into Y-TZP. Materials and methods: CNT were coated with zirconium oxide and yttrium oxide to form a powder (CNT/ZYO) using a hydrothermal co-precipitation method. Powders made of Y-TZP + (CNT/ZYO) were produced using 99 vol% of Y-TZP and 1 vol% of CNT/ZYO. CAD-CAM blocks (42.5×16.0×16.0mm) were obtained by uniaxial pressing (67MPa/30 s) of each powder in a steel matrix. These blocks were partially sintered at argon atmosphere (1100 ◦C/1 h/5 ◦C/s) and then sectioned to produce 14 bar-shaped specimens (3.0×4.0×25.0mm/edges chamfered according to ISO6872:2008) of each material, which were sintered also in argon atmosphere (1.400 ◦C/4 h/5 ◦C/min). Density measured by Archimedes’ method was used to calculate the relative density (RD), based on the theoretical values for both materials (6.06 g/cm3). Flexural strength (FS) was measured in four-point bending with specimens immersed in water at 37 ◦C (inner and outer supports of 10 and 20 mm). CFL was determined in four-point bending, using the staircase method (10,000 cycles/5 Hz). In each cycle, the stress varied between the maximum stress (MS) and 50% of MS. The applied stress in the first specimen was 50% of FS. After 10,000 cycles, in case the specimen did not fracture, 10MPa was added to the next specimen. RD and FS were analyzed by Student’s t test (alpha = 5%). CFL was calculated according to: CLF =X0+d(SUMini/SUMni±0.5), where X0 is the lowest stress value tested, d is the stress added or subtracted to each cycle and n is the number specimens that survived or failed in each stress level. The lowest stress level was computed as i = 0, and the next one was computed as i=1, and so on. Fracture surfaces were fractographically analyzed. Results: Specimens containing nanotubes showed significantly lower RD compared to the control (p = 0.009). Nanotube addition also caused a 50% significant decrease in FS (p = 0.003). However, the FS coefficient of variation for the control was higher (17%) compared to that of the composite (10%). CFL calculated for the control was 2.5 times higher than that of the composite. The %CFL (CFL in terms of percentage of the FS) was also higher for the control. Fractography indicated fracture origins associated to surface defects and porous regions related to nanotube agglomerates. Conclusions: The processing method used to produce the composite Y-TZP/nanotubes needs to be improved since nanotube addition to Y-TZP caused a significant reduction of the relative density, strength and fatigue limit.

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  • IPEN-DOC 12969

    MULLER, FRANK A.; BOTTINO, MARCO C.; MULLER, LENKA; HENRIQUES, VINICIUS A.R.; LOHBAUER, ULRICH; BRESSIANI, ANA H.A. ; BRESSIANI, JOSE C. . In vitro apatite formation on chemically treated (P/M) Ti-13Nb-13Zr. Dental Materials, v. 24, p. 50-56, 2008.

    Palavras-Chave: titanium alloys; powder metallurgy; body fluids; simulation; surface treatments; apatites

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  • IPEN-DOC 17285

    MONTEIRO, GABRIELA Q.M.; MONTES, MARCOS A.J.R.; GOMES, ANDERSON S.L.; MOTA, CLAUDIA C.B.O.; CAMPELLO, SERGIO L.; FREITAS, ANDERSON Z. . Marginal analysis of resin composite restorative systems using optical coherence tomography. Dental Materials, v. 27, n. 12, p. e213-e223, 2011.

    Palavras-Chave: dentistry; teeth; composite materials; adhesives; cements; resins; tomography; optical models; light scattering; coherence length

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  • IPEN-DOC 24488

    MIRANDA, R.B.P.; MARCHI, J.; USSUI, V. ; LAZAR, D.R.R. ; MIRANDA, W.G.J.; CESAR, P.F.. Mechanical properties of Y:TZP/TiO2 coated with hydroxyapatite for dental implants. Dental Materials, v. 33, suppl. 1, p. e54-e54, 2017. DOI: 10.1016/j.dental.2017.08.106

    Abstract: Purpose/aim: (1) To investigate the effect of titania content in mol% (0, 10 and 30) in the specific surface area (SBET), the size of the agglomerates and the intensity of the peaks corresponding to crystalline phase present in the ceramic powder of Y:TZP/TiO2; (2) to investigate the effect of titania addition (0, 10 and 30 mol%) on the microstructure, relative density (RD), Young’s modulus (E), Poisson’s ratio (PR), flexural strength ( f) andWeibull modulus (m) of a Y:TZP/TiO2 composite; and (3) to investigate the effect of the presence of a biomimetic coating on the microstructure and mechanical properties ( f and m) of Y:TZP/TiO2 composite. Materials and methods: Y:TZP (3mol% of yttria) and Y:TZP/TiO2 composite (10 or 30mol% of titania) were synthesized using a co-precipitation route. The powders were pressed and sintered at 1400 ◦C/2 h. Half of the discs were subjected to biomimetic coating. The powderswere characterized by X-ray diffraction (XRD), laser scattering, gas adsorption and scanning electron microscopy (SEM). The surfaces, with and without biomimetic coating, were characterized by SEM and XRD. The RD was measured by the Archimedes’ principle. E and PRwere measured by ultrasonic pulse-echo method. For the mechanical properties the specimens (n = 30 for each group) were tested in a universal testing machine. Weibull modulus was estimated by the maximum likelihood method and ANOVA with Tukey test (˛ = 5%) was used to evaluate f, E and RD. Results: All powders had a SBET greater than 42m2/g and the titania addition favored the formation of larger agglomerates. Titania addition increased the grain size of the composite and caused a significant decrease in the f in MPa (control: 815.4a; T10: 455.7b and T30: 336.0c), E in GPa (control: 213.4a; T10: 155.8b and T30: 134.0c) and relative density in % (control: 99.0a; T10: 94.4c and T30: 96.3b) of the Y:TZP/TiO2 composite. The presence of 30% titania caused substantial increase in m and PR. Biomimetic coating resulted in the formation of apatite globules heterogeneously distributed on the surface of the material and this treatment did not significantly alter the f and m of the composite (Table 1). Conclusions: The Y:TZP/TiO2 composite coated with a layer of CaP has great potential to be used as implant material. Properties of the powderwere affected by titania addition. Addition of titania toY:TZP caused an increase in grain size, a significant decrease in f, E and RD. The presence of biomimetic coating did not jeopardize the reliability of Y:TZP/TiO2 composite.

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  • IPEN-DOC 24482

    ARATA, A. ; PRETTO, L.R. de ; USSUI, V. ; LIMA, N.B. ; FREITAS, A.Z. ; MACHADO, J.P.B.; TANGO, R.N.; SOUZA, G.M. de; LAZAR, D.R.R. . New method for depth analysis of Y-TZP t-m phase transformation. Dental Materials, v. 33, suppl. 1, p. e6-e6, 2017. DOI: 10.1016/j.dental.2017.08.009

    Abstract: Purpose/aim: The aim of this studywas to validate the optical coherence tomography (OCT) as a nondestructive method of analysis to evaluate the depth of tetragonal to monoclinic (t-m) transformed zone and to calculate the kinetics of phase transformation of a monolithic Y-TZP after hydrothermal aging. Specifically, to compare the activation energy of t-m transformation calculated by the depth of the transformed zone using scanning electron microscopy (SEM) and OCT. Materials and methods: Fully sintered (1450 ◦C/2 h) discs of dentalY-TZP (LAVAPLUS, 3M-ESPE)were aged in hydrothermal pressurized reactor to follow the phase transformation kinetics at 120 to 150 ◦C. Four samples per aging time were analyzed by OCT (OCP930SR, Thorlabs Inc.), = 930 nm, spectral bandwidth (FWHM) of 100 nm, nominal resolution of 6 m (lateral and axial) in air, declared digital resolution 3.09 m (axial). Three areas of 3mm (lateral) were observed to calculate the phase transformation depth (Image J). X-ray diffraction analysis (XRD) were performed, Cu-K , 20◦ to 80◦, 2 . The data were refined using the Rietveld method (GSAS). The transversal section of one specimen of each group was submitted to backscattered SEM analysis to calculate the phase transformation depth (Image J). The speed of the transformation zone front was determined plotting the phase transformation depth versus aging time. Results: XRD results indicated that Y-TZP that 66% is the maximum value of monoclinic phase concentration for all aged Y-TZP. The activation energy for the monolithic Y-TZP was 107.53 kJ/mol. One year and 5 years of hydrothermal aging at 37 ◦C will present approximately 4.21% and 15% of monoclinic phase, respectively. The comparison of the depth of the transformed zone using SEM and OCT were similar, showing a linear behavior and providing information that the opaque layer observed by OCT is related to the depth of the transformed zone (Fig. 1), any difference among the results could be a result of the refraction index correction. The energy of activation calculated by SEM and OCT were 114 kJ/mol and 100 kJ/mol, respectively. The speed calculated for the phase transformation into the bulk of the transformed zone estimated for 37 ◦C was 0.04 m/year (SEM) and 0.16 m/year (OCT). Conclusions: The results indicate that activation energy values determined by SEM and OCT observations were similar allowing the use of the OCT as a tool for monolithic Y-TZP t-m phase transformation kinetic evaluation. Moreover, OCT method has the advantage of a shorter analysis time, without the need of sample preparation steps.

    Palavras-Chave: crystal-phase transformations; tomography; optical modes; coherence length; scanning electron microscopy; measuring methods

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  • IPEN-DOC 19529

    MARCHI, JULIANA ; AMORIM, ERIC M.; LAZAR, DOLORES R.R. ; USSUI, VALTER ; BRESSIANI, ANA H.A. ; CESAR, PAULO F.. Physico-chemical characterization of zirconia-titania composites coated with an apatite layer for dental implants. Dental Materials, v. 29, n. 9, p. 954-962, 2013.

    Palavras-Chave: teeth; implants; biological materials; ceramics; composite materials; zirconium oxides; titanium oxides; coatings; apatites; fourier transform spectrometers; x-ray diffraction; scanning electron microscopy

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  • IPEN-DOC 26689

    SAMPAIO, CAMILA S.; ARIAS, JESSICA F.; ATRIA, PABLO J.; CACERES, EDUARDO; DIAZ, CAROLINA P.; FREITAS, ANDERSON Z. ; HIRATA, RONALDO. Volumetric polymerization shrinkage and its comparison to internal adaptation in bulk fill and conventional composites: A μCT and OCT in vitroanalysis. Dental Materials, v. 35, n. 11, p. 1568-1575, 2019. DOI: 10.1016/j.dental.2019.07.025

    Abstract: Objective. To quantify the volumetric polymerization shrinkage (VPS) of different conventional and bulk fill resin composites, through micro-computed tomography (μCT), and qualitative comparison of gap formation through optical coherence tomography (OCT). Methods. Box-shaped class I cavities were prepared in 30 third-molars and divided into 5 groups (n = 6): G1- Filtek Z100 (Z100); G2- Tetric Evoceram Bulk Fill (TEC); G3- Tetric EvoFlow Bulk fill (TEF); G4- Filtek Bulk fill (FBU); and G5- Filtek Bulk fill Flowable (FBF). All groups were treated with Adper Single Bond Plus adhesive and light cured (Bluephase 20i). Each tooth was scanned three times using a μCT apparatus: after cavity preparation (empty scan); after cavity filling (uncured scan) and after light curing of the restorations (cured scan). The μCT images were imported into a three-dimensional rendering software, and volumetric polymerization shrinkage percentage was calculated (%) for each sample. In the same images, interfacial gaps in the pulpal floor were qualitatively evaluated. After μCT evaluation, the pulpal floor from each tooth was polished until a thin tooth structure was obtained and OCT images were obtained by scanning the pulpal portion. Gap formation was observed and qualitatively compared to the μCT images.

    Palavras-Chave: polymerization; shrinkage; volumetric analysis; computerized tomography; optical systems; optical modes; coherence length; resins; composite materials; biological recovery

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  • IPEN-DOC 13138

    LAZAR, DOLORES R.R. ; BOTTINO, MARCO C.; OZCAN, MUTLU; VALANDRO, LUIZ F.; AMARAL, REGINA; USSUI, VALTER ; BRESSIANI, ANA H.A. . Y-TZP ceramic processing from coprecipitated powders: A comparative study with three commercial dental ceramics. Dental Materials, v. 24, p. 1676-1685, 2008.

    Palavras-Chave: aluminium oxides; teeth; ceramics; fracture properties; zirconium oxides; comparative evaluations

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  • IPEN-DOC 23549

    ARATA, A. ; PRETTO, L.R. de ; USSUI, V. ; LIMA, N.B. ; FREITAS, A.Z. ; MACHADO, J.P.B.; TANGO, R.N.; SOUZA, G.M.D. de; LAZAR, D.R.R. . Y-TZP low temperature degradation: a sigmoidal or a linear behavior?. Dental Materials, v. 32, 1, p. e99-e99, 2016. DOI: 10.1016/j.dental.2016.08.208

    Palavras-Chave: yttrium oxides; zirconium oxides; aging; hydrothermal systems; temperature dependence; x-ray diffraction

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  • IPEN-DOC 25567

    MANARAO, D.S.; CORDEIRO, G.L. ; TERTULIANO, A.J.O.; MACHADO, I.F.; LAZAR, D.R.R. ; USSUI, V. ; CESAR, P.F.. Y-TZP reinforced with reduced graphene oxide: evaluation of processing conditions. Dental Materials, v. 34, Suppl. 1, p. e72-e73, 2018. DOI: 10.1016/j.dental.2018.08.149

    Abstract: Purpose/aim: To develop a processing method for yttrium stabilized zirconia pollycrystal (YTZP) reinforced with reduced graphene oxide (rGO) and to verify the effect of rGO concentration on hardness and fracture toughness of the material. Materials and methods: The composite production included several steps: (a) synthesis of Y-TZP powder by coprecipitation route, (b) synthesis of graphene oxide from chemical exfoliation of graphite (modified Hummer’s method) followed by reduction with ascorbic acid, (c) sonication of reduced graphene oxide in Y-TZP suspension followed by drying (d) uniaxial pressing in metal device with diameter of 5mm and (e) sintering in a conventional tubular furnace (Argon/4%hydrogen atmosphere) or spark plasma sintering (SPS). The concentration of rGO in Y-TZP was fixed between 0.01 and 2.0 wt%. Sintered samples were characterized by X-ray diffraction, scanning electron microscopy, density measurements, and Vickers method for hardness and fracture toughness determination (indentation fracture). Data were analyzed by ANOVA and Tukey’s test with global significance level of 5%. Results: Results (Table 1) showed that the procedure stablished for dispersion of rGO in the Y-TZP resulted in good physical homogeneity of rGO and Y-TZP. Regarding the sintering procedure, it was observed that conventional sintering in a controlled atmosphere was not effective for ceramic densification due to microcrack formation at the ceramic surface. For conventional sintering, the hardness obtained for the rGO concentration of 2% was significantly lower than those obtained for all other concentrations, however, for this processing method, fracture toughness was not affected by rGO concentration. For SPS, both fracture toughness and hardness were affected by rGO concentration, with the lowest hardness mean value measured for the concentration of 0.05% and the lowest fracture toughness value measured for specimens with addition of 0.01% of rGO. Conclusions: The production of the composite Y-TZP/rGO was proved possible, and sintering via spark plasma resulted in higher mechanical properties of the composite material compared to conventional sintering. rGO concentration affected the hardness of the composite for both processing methods (conventional and SPS), however fracture toughness was only affected by rGO concentration for specimens processed via SPS.

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A pesquisa apresentará melhor resultado selecionando um dos filtros disponíveis em Navegar

Os filtros disponíveis em Navegar tais como: Coleções, Ano de publicação, Títulos, Assuntos, Autores, Revista, Tipo de publicação são autoexplicativos. O filtro, Autores IPEN apresenta uma relação com os autores vinculados ao IPEN; o ID Autor IPEN diz respeito ao número único de identificação de cada autor constante no RD e sob o qual estão agrupados todos os seus trabalhos independente das variáveis do seu nome; Tipo de acesso diz respeito à acessibilidade do documento, isto é , sujeito as leis de direitos autorais, ID RT apresenta a relação dos relatórios técnicos, restritos para consulta das comunidades indicadas.

A opção Busca avançada utiliza os conectores da lógica boleana, é o melhor recurso para combinar chaves de busca e obter documentos relevantes à sua pesquisa, utilize os filtros apresentados na caixa de seleção para refinar o resultado de busca. Pode-se adicionar vários filtros a uma mesma busca.

Exemplo:

Buscar os artigos apresentados em um evento internacional de 2015, sobre loss of coolant, do autor Maprelian.

Autor: Maprelian

Título: loss of coolant

Tipo de publicação: Texto completo de evento

Ano de publicação: 2015

Para indexação dos documentos é utilizado o Thesaurus do INIS, especializado na área nuclear e utilizado em todos os países membros da International Atomic Energy Agency – IAEA , por esse motivo, utilize os termos de busca de assunto em inglês; isto não exclui a busca livre por palavras, apenas o resultado pode não ser tão relevante ou pertinente.

95% do RD apresenta o texto completo do documento com livre acesso, para aqueles que apresentam o significa que e o documento está sujeito as leis de direitos autorais, solicita-se nesses casos contatar a Biblioteca do IPEN, bibl@ipen.br .

Ao efetuar a busca por um autor o RD apresentará uma relação de todos os trabalhos depositados no RD. No lado direito da tela são apresentados os coautores com o número de trabalhos produzidos em conjunto bem como os assuntos abordados e os respectivos anos de publicação agrupados.

O RD disponibiliza um quadro estatístico de produtividade, onde é possível visualizar o número dos trabalhos agrupados por tipo de coleção, a medida que estão sendo depositados no RD.

Na página inicial nas referências são sinalizados todos os autores IPEN, ao clicar nesse símbolo será aberta uma nova página correspondente à aquele autor – trata-se da página do pesquisador.

Na página do pesquisador, é possível verificar, as variações do nome, a relação de todos os trabalhos com texto completo bem como um quadro resumo numérico; há links para o Currículo Lattes e o Google Acadêmico ( quando esse for informado).

ATENÇÃO!

ESTE TEXTO "AJUDA" ESTÁ SUJEITO A ATUALIZAÇÕES CONSTANTES, A MEDIDA QUE NOVAS FUNCIONALIDADES E RECURSOS DE BUSCA FOREM SENDO DESENVOLVIDOS PELAS EQUIPES DA BIBLIOTECA E DA INFORMÁTICA.

O gerenciamento do Repositório está a cargo da Biblioteca do IPEN. Constam neste RI, até o presente momento 20.950 itens que tanto podem ser artigos de periódicos ou de eventos nacionais e internacionais, dissertações e teses, livros, capítulo de livros e relatórios técnicos. Para participar do RI-IPEN é necessário que pelo menos um dos autores tenha vínculo acadêmico ou funcional com o Instituto. Nesta primeira etapa de funcionamento do RI, a coleta das publicações é realizada periodicamente pela equipe da Biblioteca do IPEN, extraindo os dados das bases internacionais tais como a Web of Science, Scopus, INIS, SciElo além de verificar o Currículo Lattes. O RI-IPEN apresenta também um aspecto inovador no seu funcionamento. Por meio de metadados específicos ele está vinculado ao sistema de gerenciamento das atividades do Plano Diretor anual do IPEN (SIGEPI). Com o objetivo de fornecer dados numéricos para a elaboração dos indicadores da Produção Cientifica Institucional, disponibiliza uma tabela estatística registrando em tempo real a inserção de novos itens. Foi criado um metadado que contém um número único para cada integrante da comunidade científica do IPEN. Esse metadado se transformou em um filtro que ao ser acionado apresenta todos os trabalhos de um determinado autor independente das variáveis na forma de citação do seu nome.

A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

1. Portaria IPEN-CNEN/SP nº 387, que estabeleceu os princípios que nortearam a criação do RDI, clique aqui.


2. A experiência do Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) na criação de um Repositório Digital Institucional – RDI, clique aqui.