FIB/SEM and SEM/EDS microstructural analysis of metal-ceramic and zirconia-ceramic interfaces

Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconiaceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers’ instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-tometal) and the two zirconia- ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000–50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metalceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing

[Measurement technics].

Aim of the research has been the evaluation of an image processing technique suggested for measuring procedures in the field of dental materials and devices studies. An analysis of measurement systems and largest employment's equipments in the biotechnologies field has been performed. Particularly, digital and image processing technologies have been considered and, between them, an evaluation of "Image Tool" software, made by UTHSCSA and available freeware on Internet has been carried out. The "Image Tool" software showed to be easy in handling and reliable on this results. Since it is based on image processing, the measuring precision is related to subject to be evaluated dimensions and always in the 1/1000 tolerance. This software also allow the direct surfaces measuring and comparing. The process accuracy is at the same level of mechanical regulation's measuring instruments (calipers, micrometres, surface probes) but it is not comparable to the laser controlled equipments, like CAD-CAM systems, micrometres and surface explores, precision which are much more sophisticated and expensives