The filler content of the dental composite resins and their influence on different properties.

The purpose of this study was to compare the inorganic content and morphology of one nanofilled and one nanohybrid composite with one universal microhybrid composite. The Vickers hardness, degree of conversion and scanning electron microscope of the materials light-cured using LED unit were also investigated. One nanofilled (Filtek™ Supreme XT), one nanohybrid (TPH®(3)) and one universal microhybrid (Filtek™ Z-250) composite resins at color A(2) were used in this study. The samples were made in a metallic mould (4 mm in diameter and 2 mm in thickness). Their filler weight content was measured by thermogravimetric analysis (TG). The morphology of the filler particles was determined using scanning electron microscope equipped with a field emission gun (SEM-FEG). Vickers hardness and degree of conversion using FT-IR spectroscopy were measured. Filtek™ Z-250 (microhybrid) composite resin shows higher degree of conversion and hardness than those of Filtek™ Supreme XT (nanofilled) and TPH®(3) (nanohybrid) composites, respectively. The TPH(3)® (nanohybrid) composite exhibits by far the lowest mechanical property. Nanofilled composite resins show mechanical properties at least as good as those of universal hybrids and could thus be used for the same clinical indications as well as for anterior restorations due to their high aesthetic properties.

Investigation of the photodynamic effects of curcumin against Candida albicans.

This study describes the association of curcumin with light emitting diode (LED) for the inactivation of Candida albicans. Suspensions of Candida were treated with nine curcumin concentrations and exposed to LED at different fluences. The protocol that showed the best outcomes for Candida inactivation was selected to evaluate the effect of the preirradiation time (PIT) on photodynamic therapy (PDT) effectiveness, the uptake of curcumin by C. albicans cells and the possible involvement of singlet oxygen in the photodynamic action. Curcumin-mediated PDT was also assessed against biofilms. In addition to the microbiological experiments, similar protocols were tested on a macrophage cell line and the effect was evaluated by Methyltetrazolium assay (MTT) and SEM analysis. The optical properties of curcumin were investigated as a function of illumination fluence. When compared with the control group, a statistically significant reduction in C. albicans viability was observed after PDT (P < 0.05), for both planktonic and biofilm cultures. Photodynamic effect was greatly increased with the presence of curcumin in the surrounding media and the PIT of 20 min improved PDT effectiveness against biofilms. Although PDT was phototoxic to macrophages, the therapy was more effective in inactivating the yeast cell than the defense cell. The spectral changes showed a high photobleaching rate of curcumin.

Fotoativação de resina composta utilizando-se laser de argônio em diferentes comprimentos de onda / Photo-activation of composite resin by the use of argon laser at different wavelengths

Muitos fatores promovem influência no processo de fotoativação. Assim, o propósito deste estudo foi avaliar a interferência de diferentes comprimentos de onda e tempos de exposição na dureza, no grau de conversão e alteração de temperatura durante a fotoativação. A resina composta microhíbrida Filtek Z-250 (3M/ESPE) na cor A2 foi utilizada na confecção dos espécimes em matriz metálica (2mm de espessura e 5mm de diâmetro), sendo fotoativadas por laser de argônio (Coerente, Innova 200-20, EUA) em modo standard com intensidade constante por 15, 40 e 60 segundos de exposição para as medidas de dureza Vickers e alteração de temperatura. Para o teste de grau de conversão, os espécimes foram fotoativados durante 10 e 20 segundos. A análise dos valores médios para os diferentes testes foram realizadas pela Análise de Variância (ANOVA) e teste Tukey (p<0,05). Foi observada diferença estatisticamente significante entre os diferentes comprimentos de onda utilizados. O comprimento de onda de 488nm promoveu os maiores valores de dureza e grau de conversão e a menor alteração de temperatura. O comprimento de onda de 488nm foi mais eficiente no processo de fotoativação.