P-11 Solid-state synthesis and in vitro characterization of Mg-doped ZrO2 bioceramics for dental applications

Biomaterials

L. Bizo^1*, M. Mureșan-Pop², R. Barabás¹, A. Berar³

¹ Babeş-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos str., RO-400028, Cluj-Napoca, Romania;

²Babeş-Bolyai University, Institute for Interdisciplinary Research on Bio-Nano-Sciences, Nanostructured Materials and Bio-Nano-Interfaces Center, 42 Treboniu Laurian str., RO-400271 Cluj-Napoca, Romania,

³“Iuliu Haţieganu” University of Medicine and Pharmacy, Faculty of Dentistry, Department of Prosthetic Dentistry and Dental Materials, 32 Clinicilor str., RO-400006, Cluj-Napoca, Romania

^* E-mail: liliana.bizo@ubbcluj.ro

Keywords: bioceramics, zirconia, solid-state synthesis, XRPD, ICP-AES, SEM/EDS

Abstract: ZrO₂-based bioceramics have been successfully used in recent years as a dental biomaterial due to their excellent properties as biocompatibility, good mechanical properties, and chemical inertness in the oral environment. ZrO₂ presents three types of crystalline structures at ambient pressure: the monoclinic phase (m-ZrO₂), stable from room temperature up to 1170 °C which exhibits poor mechanical properties, the tetragonal phase (t-ZrO₂), which is stable in the temperature range 1170-2370 °C and has good mechanical properties, and the cubic phase (c-ZrO₂), which is stable above 2370 °C and has moderate mechanical properties [French et al, 1994; Denry & Kelly, 2008]. To prevent the volume expansion during cooling, ZrO₂ can be stabilized with different oxides like MgO, CaO, Y₂O₃, CeO₂, using different methods of synthesis.

In this work, Zr_2-xMg_xO₂ (x = 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3) was synthesized by solid-state reaction at high temperature, followed by their in vitro characterisation. The analysis of the amount of Zr⁴⁺ and Mg²⁺ ions dissolved in the Xerostom^® saliva substitute gel after two months exposure times, using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) technique, showed dissolution of Mg²⁺. The XRPD (X-ray powder diffraction) technique was employed to investigate the phase transformations occurring during the degradation process in Xerostom^®. The results revealed that the t-ZrO₂ is the predominant phase for all the prepared compositions. The coexistence of both t– and m-ZrO₂ phases on the x = 0.1 composition was evidenced. Moreover, an examination by SEM/EDS (scanning electron microscopy/energy dispersive X-ray spectroscopy) showed interconnected grains in the sintered ceramics and confirmed the presence of Mg, Zr, and O, with a homogenous distribution throughout the samples.

References

French, R.H.; Glass, S.J.; Ohuchi, F.S.; Xu, Y.-N.; Ching, W.Y. (1994). Experimental and theoretical determination of the electronic structure and optical properties of three phases of ZrO₂. Phys. Rev., 49, 5133–5142

Denry, I.; Kelly, J.R. (2008). State of the art of zirconia for dental applications. Dent. Mater., 24, 299–307

Acknowledgments

The present research leading to the above-presented results has received funding  from UEFISCDI under the project number PN-III-P3-36-H2020-2020-0058 and COST (European Cooperation on Science and Technology) Action CA18112 – Mechanochemistry for Sustainable Industry.