Papers by Author: Bin Gu

Abstract: Objective: To evaluate the colouration of zirconia ceramic by adding two kinds of rare earth oxides. Methods: Added different concentrations of Fe₂O₃ and CeO₂ in tetragonal zirconia poly crystals stabilized with 3Y-TZP powder compacted at 200MPa using cold isostatic pressure, and fully sinter. The chromaticity of sintered bodies was measured with spectrophotometer. Results: self-colored zirconia by two kinds of rare earth oxides: The lightness of zirconia by adding cerium oxides was about 85 and a* decreased slightly. The color shifted to more yellow-green color. The chroma of the ceramics became more intensity, the lightness decreased with the increasing of the content of ferrum oxides and the color change to red-yellow direction. Conclusion: Zirconia ceramic could be colorized by Fe₂O₃ and CeO₂.

Abstract: Objective:To study the relative translucency of 5 veneered and glazed all-ceramic systems core material, including Procerra AllCeram Alumina, Vita In-Ceram Zirconium, Ivoclar Vivodent Empress, In-Ceram Spinell and Colored Zirconia. Methods: Under standard black and white background, the surface light reflectivity of 5 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 5 core materials all declined, and ranged from 0.6740 of In-Ceram Spinell to 1.00 of In-Ceram zirconia, among of that In-Ceram Spinell was most transparent. Conclusion: Among the groups, there is no significant differences among Empress II, Procera AllCeram and Colored Zirconia (IL1,IL2,IL3). Compared with Procera AllCeram and Vita In-Ceram Zirconium , Procera AllCeram has significant difference. There is a significant difference between Procera AllCeram and In-Ceram Spinell.

Abstract: Objective: To study the relative translucency of 4 veneered and glazed all-ceramic systems core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium, Ivoclar Vivodent Empress and Colored Zirconia. Methods: Under standard black and write background, the surface light reflectivity of 4 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 4 core materials all declined, and ranged from 0.8015 of Colored Zirconia to 1.00 of In-Ceram zirconia, among of that Empress II and Colored Zirconia were most transparent. Conclusion: Among the groups, there is no significant difference between Empress II and Colored Zirconia(IL1,IL2,IL3). Compared with Vita In-Ceram Alumina and Vita In-Ceram Zirconium, Vita In-Ceram Alumina(AL1) has significant difference. There is no significant difference between Vita In-Ceram Zirconium and Vita In-Ceram Alumina(AL2,AL3,AL4).

Abstract: Objective: We aimed to develop a multi-functional CCS/CCM (Computerized Color Selecting/Computer Color Matching) software so as to provide more practical colorimetric software for clinical use and further researches. Methods: This software used the 6 dental prosthetic materials and color data from 4 shade guide system which were most frequently-used in clinic currently as basic database, to program 5 functional blocks including respectively CCS/CCM system; Dental Material Chromatic Value System; Vita Information System; Transformation of Colorimeter System; and Chromatic Value Difference Analysis. These modules had the functions of information inquiry of different types of dental materials and their corresponding chromatic value, color matching, transforming, and color difference analysis. Results: The software had a convenient operation interface which could guarantee a stable performance. Containing various shade block and chromatic value, and transformation among different colors, this software analysed the color difference in the database, improved the accuracy and reliability of dental color choosing, and, to some extent, increased the color repetition rate of prosthesis. Conclusion: The software could well meet the needs of clinical dental colorimeter and choosing, increase the color repetition rate of prosthesis, and easily finish the transformation among different colors. It had more functions to adapt clinical need.

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: 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.