S 4300

The three luting agents were evaluated with a scanning electron microscope (SEM, S-4300, Hitachi High-Technologies, Tokyo, Japan). Each luting agent was filled into the brass ring, polymerized with the curing unit, and stored in the dark for 30 min. The surfaces of the specimens were ground with a #1,200-grit silicon carbide abrasive paper. The specimens were then mounted on stubs and adequately dried in a vacuum desiccator for 24 h. After osmium coating with a sputter coater (HPC-1S, Vacuum Device, Mito, Japan) for 30 s, the specimens were observed with a microscope with an accelerating voltage of 15 kV.

To determine the failure mode, the fractured surfaces of the specimens were observed at 32× magnification using a stereoscopic microscope (Stemi DV4, Carl Zeiss, MicroImaging, Göttingen, Germany). The failure modes were categorized as follows: (A) adhesive failure at the zirconia/composite resin interface, (B) combination of adhesive failure at the zirconia/composite resin interface and cohesive failure within the composite resin, (C) adhesive failure at the zirconia/glazed layer interface, (D) combination of adhesive failure at the zirconia/ glazed layer interface and cohesive failure within the glazed layer, (E) adhesive failure at the glazed layer/ composite resin interface, (F) combination of adhesive failure at the glazed layer/composite resin interface and cohesive failure within the glazed layer, (G) combination of adhesive failure at the glazed layer/composite resin interface and cohesive failure within the composite resin, and (H) cohesive failure within the composite resin (Fig. 2). Representative specimens were sputter-coated with osmium (HPC-IS, Vacuum Device, Mito, Japan) and imaged by scanning electron microscope (SEM; S-4300, Hitachi High-Technologies, Tokyo, Japan). The representative specimens were also analyzed using an X-ray diffractometer (Miniflex, Rigaku, Tokyo, Japan) with Cu Kα radiation by scanning over the diffraction angle (2θ) range of 3°-90°.

Before primer application and after shear bond strength testing, the selected metal specimens were sputter coated with osmium for 30 s. The surfaces were then undertaken using SEM (S-4300, Hitachi High Technologies, Tokyo, Japan, and ERA-8800FE, Elionix, Tokyo, Japan) with an acceleration voltage of 15 kV.

A LA system (UP213, Electro Scientific Indutries (ESI), Portland, OR, USA) and an ICPMS instrument (Agilent 7500ce, Agilent Technologies, Tokyo, Japan) were used in this study (Table 2). A pressure vessel with a stainless-steel jacket (HU-50, San-ai Kagaku, Aichi, Japan) was used for the acid digestion of SiC powders and sintered SiC cracked with a hammer. SiC particles were observed by scanning electron microscopy (SEM; S-4300, Hitachi High Technologies, Tokyo, Japan). For SEM measurements, the surfaces of all the samples were coated with a Pt/Pd alloy by means of an ion sputtering device (E-1045, Hitachi High Technologies, Tokyo, Japan).
Dynamic light scattering (ELSZ-2000ZS, Otsuka Electronics Co., Osaka, Japan) was used to measure the diameter distribution of LAL-sampled particles. A semiconductor laser with a wavelength of 660 nm was used.
The LAL-sampled particles of sintered SiC and single-crystal SiC were placed on a glass slide by means of a needle, and their chemical compositions were measured by laser Raman microscopy (RAMAN-11, Nanophoton Corporation, Osaka, Japan; laser wavelength, 532 nm). This method enabled us to analyze individual particles.