No abstract

Shadepilot was the only instrument tested in the present study that showed high accuracy and reliability both in vitro and in vivo. As different L*a*b* values and shade matching results were reported using various instruments for the same tooth, a combination of the evaluated shade matching instruments and visual shade confirmation is recommended for clinical use. SUMMARYThis study evaluated the accuracy and reliability of three computer-aided shade matching instruments (Shadepilot, VITA Easyshade, and ShadeEye NCC) using both in vitro and in vivo models. The in vitro model included the measurement of five VITA Classical shade guides. The in vivo model utilized three instruments to measure the central region of the labial surface of maxillary right central incisors of 85 people. The accuracy and reliability of the three instruments in these two evaluating models were calculated. Significant differences were observed in the accuracy of instruments both in vitro and in vivo. No significant differences were found in the reliability of instruments between and within the in vitro and the in vivo groups. VITA Easyshade was significantly different in accuracy between in vitro and in vivo models, while no significant difference was found for the other two instruments. Shadepilot was the only , 2012, 37-3, 219-227 instrument tested in the present study that showed high accuracy and reliability both in vitro and in vivo. Significant differences were observed in the L*a*b* values of the 85 natural teeth measured using three instruments in the in vivo assessment. The pair-agreement rates of shade matching among the three instruments ranged from 37.7% to 48.2%, and the incidence of identical shade results shared by all three instruments was 25.9%. As different L*a*b* values and shade matching results were reported for the same tooth, a combination of the evaluated shade matching instruments and visual shade confirmation is recommended for clinical use.

The purpose of this study was to investigate the effect of zircon-based tricolor pigments (praseodymium zircon yellow, ferrum zircon red, and vanadium zircon blue) on the color, thermal property, crystalline phase composition, microstructure, flexural strength, and translucency of a novel dental lithium disilicate glass-ceramic. The pigments were added to the glass frit, milled, pressed, and sintered. Ninety monochrome samples were prepared and the colors were analyzed. The effect of the pigments on thermal property, crystalline phase composition, and microstructure were determined by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Addition of the pigments resulted in the acquisition of subtractive primary colors as well as tooth-like colors, and did not demonstrate significant effects on the thermal property, crystalline phase composition, microstructure, and flexural strength of the experimental glass-ceramic. Although significant differences (p < 0.01) were observed between the translucencies of the uncolored and 1.0 wt % zircon-based pigment colored ceramics, the translucencies of the latter were sufficient to fabricate dental restorations. These results indicate that the zircon-based tricolor pigments can be used with dental lithium disilicate glass-ceramic to produce abundant and predictable tooth-like colors without significant adverse effects, if mixed in the right proportions.

Influence of different kinds and mixing amount of the alkaline activators on the strength of fly ash-cement gel sand materials is discussed through experiment wit 29 group test specimen. The rupture strength and the compressive strength with the age of 3 and 28 days of test blocks mixed with NaOH or CaO are compared each other. The early activity of fly ash can be activated by mixing the alkaline activator. The early activity of fly ash can be activated by mixing with the alkaline activators. The setting time of fly ash-cement binders becomes better. And the early strength can be improved. The activated effect of fly ash-cement binders by different type of the alkaline activators is affected by the age of test blocks. The activated effect mixed with CaO is better than the effect mixed with NaOH.

Palm oil fuel ash (POFA) has been known to be a good pozzolanic material and played an effective role in improving the physical and mechanical properties of concrete. This paper highlights the results obtained from the laboratory tests on compressive strength, modulus of elasticity, creep and shrinkage of glass fibre reinforced concrete (GFRC) containing POFA. Concrete specimens of grade 30 was designed following DoE method where GFRC with 0.5% fibre content was prepared with OPC replaced by 20% POFA by weight. Laboratory tests based on short-term investigation showed that the modulus of elasticity of GFRC containing POFA in association with its compressive strength was slightly lower than that of concrete without POFA. The measured values of creep and shrinkage, however, revealed that the creep and shrinkage strain of GFRC containing POFA were higher than that of concrete with OPC alone. On the basis of short-term investigation, the one-year creep and shrinkage values of both types of concrete were also predicted by extrapolating the data obtained in this study.