Evaluation of zirconia-porcelain interface using X-ray diffraction / 国际口腔科学杂志·英文版

The aim of this study was to determine if accelerated aging of porcelain veneering had an effect on the surface properties specific to a tetragonal-to-monoclinic transformation (TMT) of zirconia restorations. Thirty-six zirconia samples were milled and sintered to simulate core fabrication followed by exposure to various combinations of surface treatments including as-received (control), hydrofluoric acid (HF), application of liner plus firings, application of porcelain by manual layering and pressing with firing, plus accelerated aging. The quantity of transformed tetragonal to monoclinic phases was analyzed utilized an X-ray diffractometer and one-way analysis of variance was used to analyze data. The control samples as provided from the dental laboratory after milling and sintering process had no TMT (Xm = 0). There was an effect on zirconia samples of HF application with TMT (Xm = 0.8%) and liner plus HF application with TMT (Xm = 8.7%). There was an effect of aging on zirconia samples (no veneering) with significant TMT (Xm = 70.25%). Both manual and pressing techniques of porcelain applications reduced the TMT (manual, Xm = 4.41%, pressing, Xm = 11.57%), although there was no statistical difference between them. It can be concluded that simulated applications of porcelain demonstrated the ability to protect zirconia from TMT after aging with no effect of a liner between different porcelain applications. The HF treatment also caused TMT.

effect of the computer luting space setting on the fracture strength of CAD/CAM generated ceramic copings

To evaluate the effect of different luting space thicknesses on the fracture strength of In-Ceram alumina [IA] and In-Ceram Zirconia [IZ] copings, and the effect of different coping materials on the fracture strength within the luting space. Material and IA and IZ copings [30 copings for each material] were machined with luting space thicknesses [20, 30, and 40 microm] for each coping thickness [0. 6, 0.8mm]. The copings were luted with Panavia 21 to composite resin dies and loaded using on Instron at a rate of 0.5mm/min until failure. Analysis of variance and t-tests were used to assess differences. There was no significant effect [p>0.05] of different luting space thicknesses on the fracture strength for each coping thickness of IA and IZ materials. There was no significant difference [P>0.05] of 20 pm between IZ [1558 +/- 82 N] and IA [1536 +/- 27 N], 30 pm be-tween IZ [1514 +/- 103 N] and IA [1589 +/- 71 N], and 40 pm between IZ [1640 +/- 102 N] and IA [1479 +/- 71 N] for 0.6 mm coping thickness. There was no significant difference [P>0.05] of 20 pm between IZ [1708 +/- 124 N] and IA [1578 +/- 80 N], 30 pm between IZ [1672 +/- 87 N] and IA [1603 +/- 131 N], and 40 pm between IZ [1588 +/- 131 N] and IA [1695 +/- 143 N] for 0.8mm coping thickness. The fracture strength of the copings was not affected by various luting space thicknesses