Dental Gold Alloys and Gold Nanoparticles for Biomedical Applications by Rebeka Rudolf & Vojkan Lazić & Peter Majerič & Andrej Ivanič & Gregor Kravanja & Karlo T. Raić

Author:Rebeka Rudolf & Vojkan Lazić & Peter Majerič & Andrej Ivanič & Gregor Kravanja & Karlo T. Raić
Language: eng
Format: epub
ISBN: 9783030987466
Publisher: Springer International Publishing

After conditioning, the α2 phase was visible in the microstructure of the Au-Pt I dental alloy, whereas, in the Au-Pt II microstructure, this phase was much bigger and more distinctive. The EDX-point analysis for all the detected phases showed that the α1-phase regions became poor in Zn, and within them there was no Rh, In and Ir. The α2 phases also contained smaller portions of Zn and Rh, and, consequently, higher concentrations of Au and Pt. The diffraction patterns for the Au-Pt I dental alloy (Fig. 2.6) showed the presence of another group of peaks (marked α2-s), shifted from the α2 phase by approximately 1º, most probably as a consequence of micro-segregation in the interior of the α2 phase. The calculated mass ratio (wt. %) for the phases of Au-Pt I after conditioning was: α1:α2:α2-s = 90.82:4.50:4.67.

After conditioning, the AuZn3 and Pt3Zn phases disappeared from the surface of the Au-Pt II alloy, such that the calculated mass ratio for the existing phases was α1:α2: Au1.4Zn0.52 = 94.28:4.67:1.05.

In the end, it can be concluded that: (a) The microstructure, but not the composition of a high noble Au-Pt dental alloy, is connected with its corrosion properties and biocompatibility in vitro; (b) The presence of the AuZn3 and Pt3Zn phases in the dental alloy led to lower corrosion stability; (c) T-cell functional tests are more sensitive for evaluating the adverse effect of Au-Pt dental alloys than a conventional MTT assay on L929 cells; (d) The influence of whole Au-Pt dental alloy extracts on the biocompatibility is more complex than the effect of Zn alone, although Zn was the only detectable element released from the dental alloys. Generally, these results contradict those published by other authors, [49, 50] who showed that dental alloy extracts had lesser cytotoxic effect than the same concentrations of Zn salt. The difference could be explained by the different compositions and microstructures of alloys, different modes of alloy conditioning, different cell culture media and different biological parameters that were monitored.

Finally, the microstructural and XRD analyses of dental alloys before and after conditioning, in combination with the analysis of element release from the alloys, could be a new approach in explaining the results of biocompatibility assays.

References

1.

Becker MJ, Turfa JMI (2017) The Etruscans and the History of Dentistry/The Golden Smile through the Ages. Taylor & Francis

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