Hierarchical BiVO 4 microspheres assembled by nanosheets were synthesized by hydrothermal process under microwave irradiation. The morphology and compositional characteristics of the BiVO 4 architectures were investigated by SEM, TEM, and XRD. The possible formation mechanism for the architectures was discussed. UV-vis diffuse reflectance spectra indicated the BiVO 4 hierarchical microspheres had absorption in both UV and vis light areas. The specific surface area and porosity of the BiVO 4 architectures were investigated by using nitrogen adsorption and desorption isotherms. Because of the narrow bandgap and the novel micro-/nanostructure, the BiVO 4 architectures show a more excellent photocatalytic activity under visible light irradiation than the BiVO 4 solid microspheres and P25. Several possible reasons for the higher photocatalytic activity have been taken into consideration, namely, high specific surface area, hierarchical mesoporous structure, and quantum size effect. In addition, the photocatalyst is stable during the reaction and can be used repeatedly.

Objectives:The objectives were to evaluate the degree of dye penetration of three different dental materials as esthetic veneer restorations on anterior teeth using stereomicroscope, and to provide reference for clinical choice.Materials and Methods:Sixty freshly extracted human maxillary central incisors were selected and randomly divided into three main groups of 20 each. Respectively, the teeth were prepared for veneer restoration by fiber-reinforced composite (FRC) (Everstick NET, Stick Tech), porcelain laminate veneer (PLV) (IPS Empress II(E-Max Press)) and 3M composites (3M ESPE) bonding with G-Cem resin cement (GC). After exposed to thermocycling (500cycles per day (5–55 °C, intervals: 30 s)) and immersed in 2% basic fuchsin dye solution for 24 h, the specimens were then sectioned buccolingual into three halves in a vertical plane parallel and measured dye penetration using stereomicroscope (Zeiss). The data collected was recorded by the dye penetration index (0–5) and statistically analysed using one-way analysis of variance (ANOVA) and T-tests using SPSS 13.Results:It is evident that the FRC group showed the lowest mean score of 0.333 mm, and the PLV group showed a highest mean score of 0.749 mm, as compared with the FRC group and the 3M composites group. Overall, when the three groups were compared for microleakage using ANOVA, there was significant difference among the groups.Conclusions:To evaluate the dye penetration of microleakage, the FRC showed a better marginal adaptability for veneer restoration. Therefore, within the limitation of this study, the use of FRC as veneer on anterior teeth can be suggested.

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