Bulk-fill composites are claimed to be restorative materials used in deep preparations and effectively photoactivated in layers up to 4 mm. The aim of the present study was to evaluate the degree of conversion, post-gel volumetric shrinkage, and cytotoxicity of six bulk-fill and two conventional composites. Degree of conversion was determined by FTIR spectroscopy; post-gel volumetric shrinkage was determined using the strain gauge method; and cytotoxicity in human fibroblasts was evaluated indirectly by the MTT assay. Data were subjected to one-way ANOVA/Tukey's test (α = 0.05). All materials, including bulk-fill and conventional composites, were classified as non-toxic, with cell viability higher than 70%. Bulk-fill composites exhibited volumetric shrinkage similar to or lower (1.4 to 0.4%) than that of conventional composites (1.7-2.1%). However, only four of the bulk-fill composites were able to sustain a homogeneous conversion at the 4-mm depth. Despite their non-toxicity and shrinkage similar to that of conventional materials, not all commercial bulk-fill materials were able to maintain a conversion as high as 80% of the superficial layer, at the 4-mm depth, indicating some failure in the bulk-fill design of some commercial brands. Therefore, the use of bulk-fill materials in dental practice is advantageous, but special attention should be given to the selection and correct use of the materials.

This work concerns to the investigation of the polymerization shrinkage and mechanical properties in dental restoratives experimental composites filled with nano clay Montmorilonite (MMT) Cloisite® 10A nanoparticles, in glycidyl methacrylate resin, using experimental composites filled with silanized Aerosil OX‐50 Silica as a control group. Six formulations with BisGMA/TEGDMA based polymeric matrix (three added with MMT and three added with silanized silica as filler) containing 50, 60, and 70 wt % were investigated. Characterization of the experimental composites was established with the following analyses: Scanning Electron Microscope, (SEM); Thermo‐Mechanical Analysis, (TMA) for Shrinkage Polymerization; Differential Scanning Calorimetry Analysis (DSC); Knoop Micro Hardness analysis; X‐ray Diffraction (XRD); Degree of Conversion (DC); Elastic Modulus and Flexural Strength; Transmission Electron Microscopy (TEM). Statistical Analyses were realized using two‐way ANOVA (type and amount of filler) and Tukey's test. TMA results showed that composites filled with MMT nanoparticle present statistically lower polymerization shrinkage values and statistically high degree of conversion in all formulations tested, when compared to composites filled with silanized silica. XRD and TEM analyses showed evidences of the intercalation phenomenon in the MMT nanoparticles in relation to BisGMA/TEGDMA polymeric matrix. However, for Flexural Strength, groups filled with MMT nanoparticle showed statistically lower values in all concentration tested. At high filler concentration it was observed the appearance of tactoids and functionalization of MMT nanoparticle did not promote a strong interface adhesion between polymeric matrix and filler. In order to adjust the mechanical properties, it would be convenient to promote the concentration optimization of MMT nanoparticles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43543.

This study concerns to the investigation of the polymerization shrinkage in dental experimental composites filled with silanized silica Aerosil V R OX-50 and clay nanoparticulated Montmorilonita (MMT) Cloisite V R 30B, in glycidyl methacrylate resin. The characterization of the experimental composites was established with the following analyses: Thermo-Mechanical Analysis (TMA) at isotherm temperature, Differential Scanning Calorimetry Analysis (DSC) under nitrogen atmosphere, X-Ray diffraction (DRX), and Micro Hardness analysis. Through the TMA analysis was observed that the polymerization shrinkage varies according to the filler type and concentration in the experimental composite. The polymerization shrinkage ranged from 0.98% to 0.22% in the experimental composites added with Cloisite V R 30B and ranged from 2.73% to 1.01% in the experimental composites containing silanized silica. Due to the intercalation of the clay nanoparticle in relation to the polymer matrix, the experimental nanocomposites with Cloisite V R 30B showed better performance compared to the composites with silanized silica. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40010.

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IntroduçãoA migrânea é o segundo distúrbio mais incapacitante do mundo, sendo que seu impacto na qualidade de vida é expressivo, sobretudo nos âmbitos profissional e emocional. Dentre os recursos não farmacológicos, estudos revelam que as atividades físicas podem ter impacto positivo no manejo dessa comorbidade. O objetivo deste estudo é buscar evidências científicas acerca da influência dos exercícios aeróbicos no manejo da dor em pacientes com migrânea.Material e métodosRealizou-se uma revisão sistemática da literatura no banco de dados PubMed, com os descritores: “Migraine AND (Aerobic activity OR aerobic exercise)”, selecionando apenas as metanálises e os ensaios clínicos publicados nos últimos 5 anos. Foram excluídos os estudos que não se enquadravam nos objetivos, restando 8 artigos para compor a revisão.ResultadosDe forma geral, os estudos apontaram que a atividade física aeróbica se mostrou favorável no tratamento da migrânea, diminuindo a frequência, a intensidade e a duração da dor, além de aumentar a aptidão física e o envolvimento dos pacientes em outras atividades do cotidiano. Um dos ensaios clínicos concluiu que a prática de atividades aeróbicas associada aos exercícios de relaxamento reduziram a sensibilidade da musculatura pericraniana/cervical, diminuindo a intensidade das crises de migrânea e a dor musculoesquelética cervical. Também, um estudo randomizado, duplo cego, apontou que a realização de exercícios aeróbicos tem efeitos terapêuticos clínicos positivos na redução da dor e nos aspectos psicológicos de mulheres com migrânea sem acesso a outras formas de tratamento. Ademais, um estudo comparativo concluiu que tanto as atividades físicas moderadas como as intensas possui impactos positivos no manejo da migrânea, no entanto, a segunda possui maior redução dos dias de enxaqueca quando comparada com a primeira. Por fim, dois artigos enfatizaram a importância da prática de exercícios físicos na população de baixa renda que possui migrânea, pois é uma terapêutica não farmacológica de baixo custo e que não apresenta efeitos adversos, reduzindo significativamente as crises dolorosas e aumentando a qualidade de vida desses pacientes, que muitas vezes não tem acesso a nenhum outro tratamento.ConclusãoA atividade física aeróbica mostrou-se uma opção terapêutica não farmacológica segura e eficaz na redução da frequência e intensidade da migrânea, além de ser mais acessível à população de baixa renda por conta de seu baixo custo.