LUIZA MELLO DE PAIVA CAMPOS

LUIZA MELLO DE PAIVA CAMPOS

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Chemical and mechanical properties of experimental dental composites as a function of formulation and postcuring thermal treatment
2018 - ESTEVES, RENATA A.; BOARO, LETICIA C.C.; GONÇALVES, FLAVIA; CAMPOS, LUIZA M.P.; SILVA, CECY M.; RODRIGUES-FILHO, LEONARDO E.
This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elasticmodulus of experimental composites. Six composites were analyzed at BisGMA: TEGDMAmolar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70wt%.The degree of conversionwas analyzed by Fourier transforminfrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170∘C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey’s test (𝛼 = 5%).The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties.The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA: TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.
Polymerization shrinkage evaluation in experimental dental composite filled with montmorillonite nanoparticles
2018 - 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.
Thermal and mechanical behavior evaluation of dental composites filled with irradiated montmorillonite
2017 - 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.
Evaluation of polymerization shrinkage in dental restorative experimental composites based: BisGMA/TEGDMA, filled with MMT
2016 - CAMPOS, LUIZA M. de P.; BOARO, LETICIA C.; FERREIRA, HENRIQUE P.; SANTOS, LETICIA K.G. dos; SANTOS, TAMIRIS M.R. dos; PARRA, DUCLERC F.
Polymerization shrinkage evaluation on nanoscale-layered silicates: Bis-GMA/TEGMA nanocomposites, in photo-activated polymeric matrices
2014 - CAMPOS, LUIZA M. de P.; LUGAO, ADEMAR B.; VASCONCELOS, MARIO R.; PARRA, DUCLERC F.