Navegação IPEN 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. DOI: 10.1016/j.dental.2009.11.131

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

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  • IPEN-DOC 27560

    JALKH, ERNESTO B.B.; MONTEIRO, KELLI N.; CESAR, PAULO F.; GENOVA, LUIS A. ; BERGAMO, EDMARA T.P.; LOPES, ADOLFO C. de O.; LIMA, ERICK; LISBOA-FILHO, PAULO N.; CAMPOS, TIAGO M.B.; WITEK, LUKASZ; COELHO, PAULO G.; BORGES, ANA F.S.; BONFANTE, ESTEVAM A.. Aging resistant ZTA composite for dental applications: microstructural, optical and mechanical characterization. Dental Materials, v. 36, n. 9, p. 1190-1200, 2020. DOI: 10.1016/j.dental.2020.05.011

    Abstract: Objective. To synthesize a zirconia toughened alumina (ZTA) composite with 70% aluminareinforced by 30% zirconia for dental applications and to characterize its microstructureand optical properties for comparison with the isolated counterpart materials and a first-generation 3Y-TZP.Methods. Disc-shaped specimens were divided in four groups (n = 70/material): (1) 3YSB-E(first generation 3Y-TZP), (2) Zpex (second generation 3Y-TZP), (3) alumina, and (4) ZTA-Zpex70/30. After synthesis, ceramic powders were pressed, and green-body samples sinteredfollowing a predetermined protocol. Specimens were polished to obtain a mirror surfacefinish. Apparent density was measured by Archimedes principle. X-ray diffraction (XRD)and scanning electron microscope (SEM) were used to characterize the crystalline contentand microstructure. Reflectance tests were performed to determine the contrast-ratio (CR)and translucency-parameter (TP). Mechanical properties were assessed by biaxial flexuralstrength (BFS) test. All analyses were conducted before and after artificial aging (20 h, 134◦C, 2.2 bar). Optical parameters were evaluated through repeated-measures analysis of variance and Tukey tests (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). Results. High density values (95–99%) were found for all ceramic materials and SEM images exhibited a dense microstructure. While XRD patterns revealed the preservation of crys- talline content in the ZTA composite, an increase in the monoclinic peak was observed for pure zirconias after aging. Significantly higher CR and lower TP values were observed for the ZTA composite, followed by alumina, 3YSB-E, and Zpex. The highest characteristic stress was recorded for 3YSB-E, followed by intermediate values between ZTA and Zpex, and the lowest for alumina. Aging affected the optical and mechanical properties of both zirconias, while remained stable for ZTA composite and alumina. Significance. The synthesis of experimental 70−30% ZTA composite was successful and its relevance for dental applications relies on its higher masking ability, aging resistance, and strength similar to zirconia.

    Palavras-Chave: composite materials; zirconium oxides; aluminium oxides; mechanical properties; optical properties; microstructure; dentistry; prostheses

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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 27377

    MIRANDA, RANULFO B. de P.; LEITE, TAYNA P.; PEDRONI, ANA C.F.; MARQUES, MARCIA M.; LIMA, NELSON B. de ; MARCHI, JULIANA; CESAR, PAULO F.. Effect of titania addition and sintering temperature on the microstructure, optical, mechanical and biological properties of the Y-TZP/TiO2 composite. Dental Materials, v. 36, n. 11, p. 1418-1429, 2020. DOI: 10.1016/j.dental.2020.08.014

    Abstract: Objective. The aims of this study were: 1) to evaluate the effect of sintering temperatureon microstructure, density and flexural strength of a 3Y-TZP/TiO2composite containing12.5 wt% of TiO2compared to 3Y-TZP specimens (control); 2) to compare 3Y-TZP with theexperimental 3Y-TZP/TiO2composite, both sintered at 1400°C, with respect to the followingparameters: optical properties, characteristic strength, Weibull modulus, fatigue behavior,induction of osteoblasts proliferation and differentiation (mineralization nodules forma-tion).Methods. The 3Y-TZP and 3Y-TZP/TiO2powders were uniaxially pressed and sintered at 1200°C, 1300°C, 1400°C or 1500°C for one hour in a furnace. The microstructural analysis con-sisted of X-ray diffraction and scanning electron microscopy. The density was measured bythe Archimedes’ principle and the flexural strength was obtained by the biaxial flexure test.The optical properties were measured using a spectrophotometer operating in the visiblelight wavelength range. The step-stress accelerated life testing was performed by the pneu-matic mechanical cycler and the biological behavior achieved by using osteoblast-like cells(Osteo-1 cell line).Results. Tetragonal zirconia was identified in all groups and cubic zirconia was identified onlyat 3Y-TZP group. The addition of TiO2decreased the values of density and flexural strength ofthe composite 3Y-TZP/TiO2in relation to 3Y-TZP regardless of the sintering temperature. Thecolor difference between the two materials was not significant regarding L*a*b* parameters.The composite showed higher probability of failure, and induced higher proliferation anddifferentiation than control. Significance. The composite developed have good aesthetic and biologics properties. However, its microstructure and mechanical properties need to be improved for future dental implant applications.

    Palavras-Chave: nanotubes; titanium oxides; dentistry; implants; yttrium oxides; zirconium oxides; sintering; behavior; biological effects; optical properties; mechanical properties; composite materials; mineralization

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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.

    Palavras-Chave: biological materials; implants; dentistry; ceramics; zirconium; yttrium

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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.

    Palavras-Chave: titanium oxides; composite materials; apatites; dentistry; implants

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  • IPEN-DOC 27561

    LOPES, A.C.O.; COELHO, P.G.; WITEK, L.; BENALCAZAR JALKH, E.B.; GENOVA, L.A. ; MONTEIRO, K.N.; CESAR, P.F.; LISBOA-FILHO, P.N.; BERGAMO, E.T.G.; RAMALHO, I.S.; CAMPOS, T.M.B.; BONFANTE, E.A.. Microstructural, mechanical, and optical characterization of an experimental aging-resistant zirconia-toughened alumina (ZTA) composite. Dental Materials, v. 36, n. 12, p. e365-e374, 2020. DOI: 10.1016/j.dental.2020.08.010

    Abstract: Objective. To evaluate the effect of aging on the microstructural, mechanical, and optical properties of an experimental zirconia-toughened alumina composite with 80%Al2O3 and 20%ZrO2 (ZTA Zpex) compared to a translucent zirconia (Zpex) and Alumina. Methods. Disc-shaped specimens were obtained by uniaxial and isostatic pressing the synthesized powders (n = 70/material). After sintering and polishing, half of the specimens underwent aging (20 h, 134 °C, 2.2 bar). Crystalline content and microstructure were evaluated using X-ray diffraction and scanning electron microscopy, respectively. Specimens underwent biaxial flexural strength testing to determine the characteristic stress, Weibull modulus, and reliability. Translucency parameter (TP) and Contrast ratio (CR) were calculated to characterize optical properties. Results. ZTA Zpex demonstrated a compact surface with a uniform dispersion of zirconia particles within the alumina matrix, and typical alumina and zirconia crystalline content. ZTA Zpex and alumina exhibited higher CR and lower TP than Zpex. ZTA Zpex and Zpex showed significantly higher characteristic stress relative to alumina. While aging did not affect optical and mechanical properties of ZTA Zpex and alumina, Zpex demonstrated a significant increase in translucency, as well as a in characteristic stress. Alumina reliability was significantly lower than others at 300 MPa, ZTA Zpex and Zpex reliability decreased at 800 MPa, except for aged Zpex. Significance. While aging did not affect the mechanical nor the optical properties of ZTA Zpex and alumina, it did alter both properties of Zpex. The results encourage further investigations to engineer ZTA as a framework material for long span fixed dental prostheses specially where darkened substrates, such as titanium implant abutments or endodontically treated teeth, demand masking.

    Palavras-Chave: microstructure; zirconium oxides; aluminium oxides; mechanical properties; optical properties; polycrystals; sintering

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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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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.

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