| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018) | |
| Biomaterial Surfaces & Interfaces | Tuesday Sessions |
| Session BI-TuP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | Atsushi Takaichi, Tokyo Medical and Dental University, Japan |
| Authors: | A. Takaichi, Tokyo Medical and Dental University, Japan Y. Kajima, Tohoku University, Japan H. Doi, Tokyo Medical and Dental University, Japan T. Hanawa, Tokyo Medical and Dental University, Japan N. Wakabayashi, Tokyo Medical and Dental University, Japan |
| Correspondent: | Click to Email |
[Objective]
In this study, we focus on using the Zr-14Nb alloy for porcelain-fused-to-metal (PFM) restoration in dental prosthetics, owing to their good mechanical properties and biocompatibility, as well as the low magnetic susceptibility. The interface between the alloy and the porcelain is of critical value in ensuring the long-term integrity of the PFM restoration, thus we investigated the changes at the ceramo-metal interface induced by preheating treatments.
[Methods]
Cylindrical cast specimens of the Zr–14Nb alloy were prepared. After sandblasting with Al2O3, the Zr–14Nb samples were subjected to a preheat treatment at 700 °C for 5, 10, or 20 min and those without treatment were taken as control samples. Dental porcelain was veneered on them; then, their bond strength (MPa) was evaluated by performing shear bond tests (n = 8/group) and the results were analyzed using ANOVA and Tukey’s tests (p = 0.05). The surface characteristics of the preheated Zr–14Nb specimens were evaluated by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), laser microscope, and X-ray diffractometry (XRD). The elemental distribution on the interface between the Zr–14Nb alloy and the porcelain was determined by SEM-EDS. MR images were obtained using 3.0 T MR scanners (MAGNETOM Spectra 3T), and artifacts volume from the specimens were quantified by constructing 3D image.
[Results and Discussion]
The samples subjected to the heat treatment for 5 min showed the highest mean bond strength (43.7±5.9 MPa). On the preheated sample groups, white oxide layers, which were predominantly composed of monoclinic zirconia, were formed, exhibiting a greater roughness than control samples; besides, on the interface of the metal–ceramics, a greater diffusion range of Nb was observed than that found on the control samples, which could contribute to increase the bond strength between porcelain and Zr-Nb alloy. On the other hand, the bond strengths of the samples subjected to 20 min preheating treatment were the lowest (33.6±3.2 MPa), which may be ascribed to the formation of a brittle thick oxide layer under excessive heat treatment.
[Conclusion]
The suitable preheat treatment performed on the Zr–14Nb substrates contributed to the increase in the surface roughness and the diffusion of Nb, which enhanced the micro-retention and chemical bonding and improved the bond strength of Zr–14Nb and porcelain. The Zr-14Nb alloy is a promising candidate for fixed dental prosthesis, as long as the appropriate treatment conditions are adopted.