RESUMO
Herein, we studied light induced interactions between two well-known luminescent materials, SrAl2O4:Eu2+, Dy3+ and nano-scale TiO2 in poly(methyl methacrylate) (PMMA). These two materials were chosen due to their stable nature, efficient spectral properties and more specifically, overlapping excitation/emission bands. When these materials were used together in 1:1 ratio by weight (w/w), the composite exhibited 76% enhancement in the emission intensity with respect to the individual phosphor. Although the luminescence mechanism of both materials is clarified in the literature, spectral interactions of them have not been studied up to now. In our opinion, the TiO2 nano-particles (TiO2 NPs) act as light-harvesting agents for the phosphor particles creating a substantial enhancement on the light absorption efficiency of the phosphor. Additionally, the TiO2 nanoparticles suggest a promising way to boost the phosphorescent activity of the SrAl2O4:Eu2+, Dy3+ by a cost-effective way and further investigation of the mechanism may be subject of future studies.
RESUMO
The purpose of this study was to determine the effectiveness of EDTA and MTAD at different temperatures as a final irrigant to remove the smear layer after the use of 5.25% NaOCl. Seventy-eight human mandibular premolars with single straight canal were prepared by a crown-down technique using rotary 0.06 taper nickel-titanium files. Final irrigation was performed with EDTA and MTAD at different temperatures. The removal of the smear layer in the coronal, middle and apical level of each canal was examined under scanning electron microscope. No difference was found between the EDTA and MTAD at 4°C, 25°C, and 37°C temperatures regardless of the canal level (coronal, middle and apical) (P = 0.286). In EDTA-25, EDTA-37, MTAD-25, and MTAD-37 groups, the difference among the coronal, middle, and apical levels were statistically no significant (P > 0.05). Our findings showed that EDTA and MTAD at 25°C and 37°C are more effective than EDTA and MTAD at 4°C even in the apical level.
