Papers by Author: Kang Lin Hou

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.

Abstract: Bilayered three-point bending strength specimen of KAVO zirconia-Vita VM9 veneering porcelain were made according to ISO6872 standard, the core to porcelain thickness ratio was 1:1. Specimens were subjected to multiple dentine porcelain firing cycles. Three-point bending strength were tested, SEM was used to observe the characteristics of the failure mode. Results show that there was no influence on the bending strength by multiple firing, the three-point bending strength were 996 ~ 1020 MPa after multiple firing, and no obvious defects was found at the interfaces. In all bilayered specimen, the bulk fracture initiated at the tensile surface of the core material and was consistently accompanied with porcelain crush and delamination at the interface.

Abstract: Objective: to evaluate the biological safety of a colored alumina/glass composite in terms of cytotoxicity and hemolytic ability. Methods: the cytotoxicity of an alumina/glass composite was evaluated with molecular filtration method. Cytotoxicity by spectrophotometric responses of test material and responses of a fresh rabbit red blood anticoagulant solution was determined by spectrophotometer. Results: cell-coated filter paper in contact with the test material showed the appearance of intracellular blue dye as the same staining density as in control samples, leading to a toxicity rating of 0. Colored alumina/glass composite assayed at <5% hemolysis. Conclusion: colored alumina/glass composite materials showed low cytotoxicity and non-acute hemolytic rates, representing overall good biological safety under these conditions.

Abstract: Objective: To study the relative translucency of 3 veneered and glazed all-ceramic systems core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium and Ivoclar Vivodent Empress. Methods: Under standard black and write background, the surface light reflectivity of 3 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 3 core materials all declined, and ranged from 0.8880 of Empress II to 1.00 of In-Ceram zirconia, among of that Empress II was most transparent. Conclusion: The relative translucency of 3 veneered all-ceramic systems core material had significant statistical difference. There was a decreasing range as Vitadur Alpha dentin (standard) > Empress II (0.8 mm) > In-Ceram Alumina > In-Ceram Zirconia.

Abstract: Objective: To study the relative translucency of 3 all-ceramics system core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium and Ivoclar Vivodent Empress II. Methods: The visible light transmittance of all samples was determined with spectrophotometer. Results: The relative translucency of dentin and opaque dentin was between 0.5958 and 0.8336, that of 3 core ceramic ranged from 0.8089 of Emp ress II to 1.00 of In-Ceram Zirconium. Conclusion: The relative translucency of 3 core material was significantly different. There was a decreasing range as Empress II > In-Ceram Alumina and In-Ceram Zirconia.

Abstract: To study the influence of background color on 3 veneered all-ceramic core materials, the color of all veneered samples that were put on noble metal, Ni-Cr alloy, Ag-Hg alloy and resin background was measured with chromatism instrument (and the chromatic aberration value among groups was Calculated). Under different backgrounds, there was significant difference in the L, a and b values among Empress II samples, there was significant difference in a and b values among In-Ceram Alumina samples, and there was no difference in the L, a and b values among In-Ceram Zirconium samples. After veneered, the influence of background color on Empress II was clear, on In-Ceram Alumina was less clear, and on In-Ceram Zirconium was void.