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Purpose: The objective of this study was to evaluate the physical and mechanical properties of a short fiber-reinforced resin composite: everX-Posterior and compare it with two bulk-fill composites, namely, Filtek Bulk-fill and Beautifil-Bulk, which are intended for large posterior restorations., Methods: Investigated properties were flexural strength, flexural modulus, surface roughness, volumetric shrinkage and depth of cure. Scanning electron microscopy images of each specimen after the flexural test were used for cross-sectional comparison. Results were analyzed using ANOVA following Tukey post-hoc test., Results: Flexural strength of everX-Posterior was comparable with two other resin composites, showing higher flexural modulus. EverX-Posterior showed the highest surface roughness after polishing and the lowest volumetric shrinkage (2.29%) among all composites used in this study. Data also showed that the everX-Posterior depth of cure was 4.24 mm, which was the highest among the three groups., Conclusion: Based on the results of this study, it was concluded that everX-Posterior as a short fiber-reinforced composite showed improvements and satisfactory performance in mechanical and physical properties, which make it a reliable base material candidate for large posterior restorations.

We observed the internal diffusion behavior of inorganic micro/nano particles through oral administration. By oral exposure, the fed particles were absorbed through the digestive system then reached some organs after internal diffusion in the body. For example, TiO2 particles fed to mice were detected in the lung, liver, and spleen after 10 days of feeding. Whereas, the absorption efficiency was extremely low compared with intravenous injection. In a comparison of the simple amount of administration, oral exposure required 102 times or more amount by intravenous injection for detection by an X-ray scanning analytical microscope. During dental treatment, micro/nano particles from tooth or dental materials would generate in the oral cavity, and some of the particles had a possibility to be swallowed, absorbed through the digestive system, and then diffuse into the body. However, our results suggest that biocompatible microparticles that are naturally taken orally affect animals only rarely because of the low absorption efficiency.

The clinical performance of dental composite restoration and its overall success are the result of physical, mechanical, and biological properties of the filling materials. The present study aimed to evaluate surface roughness, flexural properties, and cytotoxicity of two nanohybrids, namely, MI Gracefil and Herculite Ultra, and one nanoceramic dental resin composite DiamondLite. The surface roughness was assessed in two different grinding conditions. Flexural properties were measured by, the three-point bending test and the specimens' fractured surface was analyzed by scanning electron microscopy. Weibull analysis was performed on the flexural strength data to determine the composites' reliability. The cytotoxicity test was conducted on MC3T3-E1 cells by the MTS assay. The results showed that grinding conditions had a significant effect on all nanocomposites' surface roughness (p <.05). Herculite Ultra had a significantly higher flexural strength (125.8 MPa) and flexural modulus (9.8 GPa) as compared to other two nanocomposites (p <.05). Further, cytotoxicity results indicated that DiamondLite had the lowest cell viability during the incubation period (p <.05). The current study, therefore, concluded that the evaluated nanocomposites showed satisfactory surface roughness. Herculite Ultra flexural properties and Weibull modulus results make it a reliable choice for direct restorations. The cell viability results also showed that all three nanocomposites had moderate cytotoxicity, making them acceptable for direct application in the mouth. [ABSTRACT FROM AUTHOR]

In this study, we investigated on suppression of metal ions elution on dental orthodontic wire. To suppress metal ion elution from stainless wire, two types of surface chemical modifications were carried out. The obtained wire were immersed into several aqueous solution then the eluted ions (Cr and Ni, which are well known to cause a metal allergy) were determined using coupled plasma mass spectrometry (ICP-MS). By both electropolymerization and self-assembly monolayer formation, the ion elution was effectively reduced. These results suggested that these surface modifications succeeded to suppress the metal ions. [ABSTRACT FROM AUTHOR]

Dental materials that are antimicrobial and acid-resistant can inhibit bacterial colonization and demineralization, thereby preventing caries. Zinc and copper are well-known for their antibacterial effect, as is nanostructured ZnO–CuO composite. Minerals such as fluorine and calcium, can remineralize and demineralize teeth. Therefore, we developed novel fluoride-containing ZnO–CuO (ZCF) nanocomposites; to the best of our knowledge, these are the first nanocomposites of this kind. The fluoride concentrations and antibacterial effects of the ZCF nanocomposites were evaluated. Nanocomposites comprising zinc and copper (ZC), and zinc, copper, and fluorine (ZCF), were prepared by a simple one-step homogeneous coprecipitation method at a low temperature (80 °C), without the use of organic solvent or surfactant. The structure and composition of the ZC and ZCF nanocomposites were examined by scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS). Quantitative analysis of the mass concentration was performed by using ZAF correction methods. The fluorine content in nanocomposites was evaluated by using proton-induced gamma emission (PIGE) at the Takasaki Advanced Radiation Research Institute in Japan. By using 96-well microtiter plates, we analyzed the antibiotic susceptibility of ZC, ZCF, and the control buffer (phosphate-buffered saline) with Streptococcus mutans (ATCC 25175). The SEM images showed that ZC and ZCF nanocomposites were composed of 3D flower-like microstructures with diameters of approximately 1 μm. Environmental SEM-EDS analysis revealed that ZC contained 43.2% Cu, 55.1% Zn, 2.2% F, and 0.1% Cl, whereas ZCF contained 47.5% Cu, 40.5% Zn, 6.7% F, and 5.9% Cl. Analysis by PIGE showed that ZCF nanocomposite contained 2553.6 ± 199.2 ppm fluorine, whereas no fluoride was detected in ZC. The control buffer enabled bacterial growth to 4 × 107 ± 9 × 106 CFU/mL, whereas ZC allowed growth of 12 ± 8 CFU/mL, and ZCF showed no bacterial growth. Thus, we developed novel fluoride-containing ZnO–CuO nanocomposites, which exhibited antibacterial effects and have the potential for remineralization, thereby demonstrating their potential as multifunctional dental materials. [ABSTRACT FROM AUTHOR]