Rong Jian Lu

Effects of Surface Treatment on the Microstructural and Crystallographic Changes of Dental 3Y-TZP Ceramic

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.

A Comparative Study on Relative Translucency of Four Dental All-Ceramic Core Materials

The aim of this study were to compare the relative translucency of four dental all-ceramic core materialsIPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia.All core materials were fabricated into samples at the diameter of 10mm and the thickness of 0.50.02mm.The relative translucency of samples were determined with color difference meter and analysed with SPSS 13.0 software.It was showed that the relative translucency of 4 all-ceramic core materials were statistically different.There was a decreasing order of their relative translucency,IPS e.max PressLava Zirconia ZenostarUpcera Zirconia.IPS e.max Press has the hightest translucency,and it was advisably used to restore anterior tooth.Upcera Zirconia was the most opaque of 4 all-ceramic core materials,and it was suitable for post tooth.

Microstructure of Interface between Zirconia and Veneer Porcelain

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.

Effect of Background Color to the Final Color of Four Highly Transparent Ceramics after Veneered

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.

Contrast Investigation on Relative Translucency of Four Ultra-Transparent Dental Zirconia Materials after Veneered

The purpose of this article is to contrast the relative translucency of four ultra-transparent dental zirconia materials after veneered, including Cercon zirconia, Zenostar zirconia, Lava zirconia and Upcera zirconia. All zirconia ceramics were prepared into samples of diameter 10mm and thickness 0.5±0.01mm.The relative translucency of samples were measured with color difference meter and statistically analyzed with SPSS 17.0.This experiment confirms that the existence of statistically significant differences in the relative translucency between different zirconia ceramics. According to the numerical level, the relative translucency of zirconia materials from high to low is Zenostar ZR Translucent>Lava Plus High Translucency zirconia> Cerconht full contour zirconia > Upcera zirconia. Zenostar ZR Translucent and Lava Plus High Translucency zirconia can be used to restore adjacent teeth that are higher translucent, while Cercon ht full contour zirconia and Upcera zirconia is better for molar teeth with poor relative translucency.

Effect of Post-Core Materials on the Color Value of Four Dental All-Ceramic Cores

The aim of this study were to compare the color value of four kinds of dental all-ceramic cores (IPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia) on three different post-core materials.All-ceramic core materials were made into samples at the diameter of 10mm and the thickness of 0.50.02mm.Their color value on the post-core material of noble metal,Co-Cr alloy and resin were respectively determined with chromatism instrument.It was showed that the color value of four all-ceramic cores were statistically different.IPS e.max Press was most obviously affected by post-core materials,while Upcera Zirconia the weakest.Lava Zirconia and Zenostar were influenced to a certain degree.In conclusion,non-mental post-core was preferable for IPS e.max Press,Upcera Zirconia was fit for any post-core materials.

The Influence of Background Color to 3 All-Ceramic System Core Materials

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.

The Transmittance Test of 3 All-Ceramic System Core Materials

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.

Colorimetric Comparison of Two Kinds of VITA Shade Guides

Our aim was to analyze the color ranges of two kinds of Vita shade guides and compare these color ranges with that of Chinese teeth. To do this, the color range and ordering of the Vita Classical and Vita 3D-Master shade guides were measured and analyzed with a MINOLTA CM-2600d spectrophotometer under a D65 standard source. The CIE-1976-L* a* b* system was adopted. We found that compared with the Vita Classical shade guide, Vita 3D Master covers a greater range of a*, and b*, which includes more yellow -reddish and more saturated color tabs. The range of L* extends further towards darker values, while in higher range the two guides are the same. Comparing these color ranges with that of Chinese teeth, the Vita 3D-Master is preferred to the Vita Classical Guide. Because of the larger range of teeth-colors covered, and the logical arrangement, we recommend the clinical use of the Vita 3D-Master shade guide.

Preparation of Pigmented Glass for Infiltration and Investigation of its Physical and Mechanical Properties

Aim To explore pigmented glass for infiltration and investigate its physical and mechanical properties. Methods The pigmented glass was prepared by melting glass components in an alumina crucible at 1400°C for 2h. The thermal properties were tested using a Setaram-TGDTA 92 analyzer; three point bending strength and fracture toughness were also tested; the microstructure of the glass was studied using a scanning electron microscope. Results The thermal expansion coefficient over the range 20–600 °C was 6.2 × 10-6 °C -1, Tg was about 690 °C, the density, bending strength, fracture toughness and Vickers hardness were 2.23 g/cm3, 118 MPa, 1.22 MPam1/2, and 7.4 GPa respectively. Conclusion The pigments have no detrimental effects on the physical and mechanical properties; thus the pigmented glass for infiltration has favorable physical and mechanical properties and also good compatibility with presintered porous alumina.