LUIZA MELLO DE PAIVA CAMPOS
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Artigo IPEN-doc 23225 Polymerization shrinkage evaluation in experimental dental composite filled with montmorillonite nanoparticles2018 - CAMPOS, LUIZA M.P.; BOARO, LETICIA C.; SANTOS, TAMIRIS M.R.; SANTOS, VINICIUS J.; GRECCO-ROMANO, REBECA; SANTOS, MARIANA J.; PARRA, DUCLERC F.This study aimed to develop experimental dental restorative composites by the addition of montmorillonite (MMT) nanoparticles in a polymeric matrix-based BisGMA/TEGDMA, to assess the possibility of a different dimensional behavior during the photo-polymerization. The characterization of experimental composites was established with the following analyses: thermal–mechanical analysis (TMA), X-ray diffraction (XRD) and transmission electron microscopy. Data for TMA were analyzed using one-way ANOVA and Tukey test (p\0.05). It was observed that the experimental composites filled with MMT nanoparticle showed statistically similar polymerization shrinkage values (by TMA analysis) in the concentration of 30% and statistically lower polymerization shrinkage values in the concentration of 50%, compared to composites filled with barium glass (BG—control groups). These results may be related to the interaction polymeric matrix/MMT nanoparticles and the formation of nanocomposites, observed by XRD and TEM analyses.Artigo IPEN-doc 23033 Thermal and mechanical behavior evaluation of dental composites filled with irradiated montmorillonite2017 - CAMPOS, L.M.P.; ZAHARESCU, T.; BOARO, L.C.; SANTOS, L.K.G.; SANTOS, T.M.R.; FERREIRA, H.P.; PARRA, D.F.The effects of pre-irradiation treatment (dose ranged from 25 to 50 kGy) of MMT (Montmorillonite) nanoclay added as filler (50 wt %) in experimental dental composites was studied; composites containing similar amounts of non-irradiated MMT were also tested. The thermal stability of the resulting material was tested by thermogravimetric analysis ranging from 50 to 800 8C. Elastic modulus and flexural strength were determined by the three point bending test (n510). Data for elastic modulus was analyzed using two way ANOVA/Tukey’s test. Data for flexural strength was analyzed using Kruskal–Wallis/Tukey’s test. For all tests, the global significance level was 5%. The modifications in elastic modulus and flexural strength with applied dose were characterized. X-ray diffraction analysis allows the depicting of intercalation phenomenon between base-polymer and nanophase. The polymeric system modified with MMT nanoparticles showed higher thermal stability by delaying the thermal degradation, compared to the control group, and the radiation dose influenced this thermal behavior directly. However, the applied dose was not sufficient to improve the mechanical properties significantly, which is related to the interaction between MMT and polymeric matrix. The pre-irradiation treatment of MMT nanoclay phase was useful for attaining efficient interaction between the two constitutive phases of the polymeric systems based bis-GMA/TEGDMA [bisphenol A bis(2-hydroxy-3-methacryloxypropyl)ether/triethyleneglycol dimethacrylate], modified with MMT nanoparticles, because the polymer component was not affected.Artigo IPEN-doc 22803 Evaluation of flexural modulus, flexural strength and degree of conversion in BISGMA/TEGDMA resin filled with montmorillonite nanoparticles2016 - CAMPOS, LUIZA M.P.; BOARO, LETICIA C.; SANTOS, TAMIRIS M.R.; MARQUES, PAMELA A.; ALMEIDA, SONIA R.Y.; BRAGA, ROBERTO R.; PARRA, DUCLERC F.This study had as its main objective to evaluate the flexural properties (strength and modulus) and degree of conversion of a dimethacrylate resin containing different amounts of nanoparticulated clay Montomorillonite (MMT) as filler. A series of composites containing similar amounts (in volume) of barium glass particles was also tested as control data. Eight formulations with polymeric matrix-based BisGMA/TEGDMA (Bisphenol A Bis(2-hydroxy-3 methacryloxypropyl)Ether/ Triethyleneglycol Dimethacrylate), four added with MMTand four added with barium glass in the volume concentration of 20, 30, 40 and 50 vol% were studied. The degree of conversion was determined using near-IR spectroscopy. Elastic modulus and flexural strength were determined by the three-point bending test. The dispersion of MMT nanoparticles was determined by means of X-ray diffraction and transmission electron microscopy analysis. The fillers montomorillonite and barium glass interacted with polymer matrix-based BisGMA/TEGDMA in a distinct manner. Although the addition of montomorillonite nanoparticles resulted in similar degree of conversion and higher elastic modulus values at all concentrations tested, only at the 20 vol% the flexural strength was statistically higher, compared to the control groups filled with barium glass. This could be related to the need of concentration optimization of montomorillonite for each type of polymer matrix in order to adjust or improve mechanical properties. The addition of low concentrations (Artigo IPEN-doc 22382 Evaluation of polymerization shrinkage in dental restorative experimental composites based: BisGMA/TEGDMA, filled with MMT2016 - CAMPOS, LUIZA M. de P.; BOARO, LETICIA C.; FERREIRA, HENRIQUE P.; SANTOS, LETICIA K.G. dos; SANTOS, TAMIRIS M.R. dos; PARRA, DUCLERC F.