Papers by Author: Long Quan Shao

Abstract: This study aimed to investigate the color value of four kinds of highly transparent ceramics (Zenostar Zirconia, Lava Zirconia, Cercon Zirconia and Upcera Zirconia)after veneered on three different post core materials including noble metal alloy, Co-Cr alloy and composite resin. Highly transparent ceramics after veneered were made into specimens with 10mm in diameter and 1.0mm in thickness. The color of core ceramics after veneered on different post core materials were measured with Color Analyzes. The results showed that their color value were significantly different from each other. Zenostar ZR Translucent and Lava Plus High Translucency Zirconia can be easily affected by the background color because of its high translucency. Therefore, resin post core materials should be selected without cause prosthesis mismatch of colors in clinical work. When making Cerconht full contour zirconia restorations, you could try to use a resin material as a post core material. And selecting precious metals, you had better make it opaque. Upcera zirconia owned a poor relative translucency, when making clinical restorations; you could use any kind of post core materials.

Abstract: The purpose of this study was to compare the transmittance of four dental all-ceramic core materials at clinical recommendation thickness.Specimens with 10mm in diameter and 0.50.01mm in thickness,including IPS e.max Press,Zenostar Zirconia,Lava Zirconia and Upcera Zirconia,were fabricated.The transmittance of specimens were measured with PR2650 spectrophotometer and measurements were analysed statistically with SPSS13.0.Experimental results showed that they had significantly different transmittance.There was a decreasing order,IPS e.max Press Lava Zirconia Zenostar Zirconia Upcera Zirconia,which were 6.1136.750 for IPS e.max,1.6042.135 for Lava Zirconia,1.5782.117 for Zenostar Zirconia and 0.9951.265 for Upcera Zirconia.

Abstract: To study the influence of background color to 3 all-ceramic system core materials.The chromaticity value of all samples that were put on noble metal, Ni-Cr alloy, Hg-Ag alloy and resign background were measured with chromatism instrument, and chromatic aberration among groups were calculated. The chromatic aberration of Empress II samples on different background color could be distinguished by human eyes, but those of Alumina and Zirconium were unable to being distinguished. In conclusion, the influence of background color to Empress II and In-Ceram Alumina of AL1 were lager. When chosen as core material, noble metals should be covered to keep prosthesis from clinical color-transform. As background to In-Ceram Alumina of AL2, it was unnecessary for resin to be covered. In-Ceram Alumina of AL3, AL4 and In-Ceram Zirconium weren’t affected by background color.

Abstract: This experiment was to study the transmittance of 3 all-Ceramic system core materials, including 4 colors of Vita In-ceram Alumina,4 colors of Vita In-Ceram Zirconium and 3 colors of Empress II,and to provide basis for clinical choice of core materials.With Vita alpha veneer porcelain as control,the transmittance of all samples was determined with spectrophotometer under D65 standard source.The transmittance of materials was 1.434%~3.843% for Vita In-Ceram Alumina,0~0.587% for Vita In-Ceram Zirconium,5.620%~6.665% for Empress II.As a whole,the transmittance of Empress IIwas the best of 3 core materials,that of In-Ceram Alumina was the worse,that of Vita In-Ceram Zirconium was the worst.

Abstract: The present paper probes into the effect of background color of different post-core materials on the core materials of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia, Cercon base color Zirconia, and Cercon base Zirconia. The spectrocolorimeter was used to measure colorimetric values of all groups of samples against the background of noble metal, nickel-chromium alloy, silver amalgam and resin, and to calculate the color difference among the groups. The result showed that the color difference of Cercon base color Zirconia viewed against different backgrounds was identifiable by human eyes (ΔE > 1.5). In contrast, the color differences of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia and Cercon base Zirconia viewed against different backgrounds were unidentifiable by human eyes (ΔE < 1.5). Based on this, it can be stated that Cercon base color Zirconia is significantly affected by background color. Thus, proper method to shelter the background color should be adopted. In addition, AL2 Electroformed Alumina, Z21 Electroformed Zirconia, and Cercon base color Zirconia are less influenced by the background color, thus it is not necessary to cover the background color.

Abstract: The spectral transmittance of six kinds of Vita In-Ceram and Cercon all-ceramic core materials after veneering ceramic was determined. Based on the production method recommended by the manufacturer, specimens of the same thickness are made. PERKIN ELMER Spectrophotometer is adopted to measure the spectral transmittance of In-Ceram AL2 slip-casting glass/alumina composite, AL2 electroformed alumina, Z21 slip-casting glass/zirconia composite, Z21 electroformed zirconia, Cercon base color zirconia and Cercon base zirconia all-ceramic core materials, after veneering ceramic. The results show that, after veneering ceramic, Cercon base Zirconia has the highest spectral transmittance, followed by AL2 Electroformed Alumina and Z21 Electroformed Zirconia, whereas the transmittance of Z21 slip-casting Glass/Zirconia composite has the lowest. Statistical data show that, among the groups, In-Ceram slip-casting Glass/Alumina composite (AL2), Electroformed Alumina (AL2), Cercon base color Zirconia and Cercon base Zirconia have significant differences between every group. On the other hand, there is no significant difference between In-Ceram slip-casting Glass/Zirconia composite (Z21) and Electroformed Zirconia (Z21). Therefore, we should choose all-ceramic restoration materials based on the spectral transmittance of all-ceramic core materials after veneering ceramic and transparency of the remaining natural teeth of patients.

Abstract: Objective: To evaluate the biological safety of a colored zirconia ceramic in terms of cellular toxicity and a skin sensitivity test. Methods: the cytotoxicity of the ceramic was evaluated by a molecular filtration method and skin irritation activity of the composite was assessed via intradermal injection of a guinea pig test solution, by inducing, enhancing, and stimulating an allergic response after local tissue exposure. Results: cell-coated filter paper in contact with test material showed the appearance of intracellular blue dye at the same staining density as in control samples, leading to a 0 toxicity rating. Guinea pigs showed no obvious erythema or edema from the irritation test, such that the assessment of colored zirconia ceramic skin allergy response in guinea pig was 0%. Conclusion: this colored zirconia ceramic showed low cytotoxicity and elicited no allergic skin inflammation response, indicating good overall biological safety under these conditions.

Abstract: Objective: To evaluate the biological safety of a colored zirconia ceramic regarding its hemolytic activity and short-term systemic toxicity. Methods: Fresh anti-coagulating rabbit blood was mixed with test materials and the hemolytic activities detected spectrophotometrically. Suspensions of the ceramic were fed to rats for one week while monitoring food consumption and relative growth rate and with subsequent pathology examinations of vital organs and tissues. Results: The hemolytic activity of the ceramics was <5%, and rats in all groups showed weekly relative growth rates of food utilization and body weight with no statistically significant differences. There were also no pathological changes observed among the various examined organs between the experimental and control groups. Conclusions: This colored ceramic showed good biocompatibility in terms of hemolytic activity and short-term systemic toxicity.

Abstract: Objective: To investigate the effects of different surface treatments on the microstructural and crystallographic changes of dental 3Y-TZP ceramics. Methods: 21 pieces of zirconia specimens (15 ´ 15 ´ 1.5 mm) were prepared and divided into 7 groups: control group; grinding group; polishing group; sandblasting group; sandblasting + veneer porcelain sintering group; sandblasting + veneer porcelain sintering twice group and sandblasting + annealing group. The crystal structure of specimen was monitored by X-ray diffraction (XRD) before morphological observation with scanning electron microscope. Results: monoclinic phase increased after grinding while decreased little after polishing, bigger phase change presented after sandblasting compared with decreased phase change induced by veneer porcelain sintering; annealing eradicated the surface m phase. Grinding produced coarse scratches on the surface of samples with removal of surface particles; after grinding and polishing to 7 um level, the surface particles were removed massively, and the surface became smooth with remaining scare scratches and substantial micro cracks. Sandblasting removed scratches near completely producing coarse and irregular surface of samples. Conclusions: Grinding, sandblasting and polishing could produce the transition of Zirconia Ceramic surface from t to m phase. It is better to use heat treatment after mechanical treatment to reverse the changed surface phase.

Abstract: To study whether the veneering technique will have an impact on zirconia grain and the bonding type and relationship on interface between zirconia and veneer porcelain. Materials and methods: After sintered, zirconia was annealed for 15 minute to finish the phase transition from m to t.4 types of veneer porcelains were sintered and observed with SEM (scanning electron microscopy) and TEM (transmission electron microscopy). Results: With etching time extending, it appeared that many materials loosed and corrosional pit deepened, enlarged in the veneer porcelain, which made crystallize structure move into veneering surface. Composition of interface mainly was amorphous glass matrix and zirconia. Energy spectrum analysis showed that there was no remnant glass composition in the zirconia side departing from interface. SEM showed that crystal in veneering side did not participate interface bonding. Conclusion: The interface between 4 types of veneer porcelains and zirconia bonded well. Veneering sintering technique didn’t change lattice structure of zirconia, which still was tetragonal structure. The specific bonding property of interface still remained to be analyzed further to determine.