Zirconia is a promising material in dental implantology as an alternative to titanium dental implants [1]. The surface properties of dental implants are considered a critical parameter for enhancing the osseointegration and thus successful implantation [2]. Surface treatment methods currently applied to zirconia-based ceramic implants copy sandblasting and etching procedures applied to titanium implants, performed in very acidic solutions [3], such as concentrated hydrofluoric acid (HF). This work studies the effect of acid corrosion surface modification on zirconia ceramic materials stabilized in their tetragonal form by 3 mol.% of yttria (3Y-TZP). Microstructural features,  surface roughness and sensitivity to low temperature degradation (LTD) were studied. For the acid corrosion surface modification, 40 % HF and its combination with 52.5 – 65 % nitric (HNO3) and 36 % hydrochloric (HCl) acids were used. Less hazardous 48 % tetra fluoroboric acid (HBF4) has also been tested as a possible substitution for HF. Polished samples were immersed in acid/s and treated for 6 hours at a temperature of 40°C. Acid corrosion surface modification effectively increased surface roughness (Ra), from  Ra = 86  ± 7 nm until  Ra = 842 ± 71 nm. Nevertheless,  accelerated aging tests (134 °C, 2 bars, up to 50 h) showed that LTD stability is also impacted by this type of acid corrosion surface modification, and thus accelerates the tetragonal (t) to monoclinic (m) phase transformation.
 
Acknowledgment:
This item is a part of dissemination activities of project FunGlass. This project has received funding from the European Union´s Horizon 2020 research and innovation programme under grant agreement No 739566. This work was also created in the frame of the project Centre for Functional and Surface Functionalized Glass (CEGLASS), ITMS code is 313011R453, operational program Research and innovation, co-funded from European Regional Development Fund. The authors would like to acknowledge European Ceramic Society funding under the JECS TRUST APPLICATION (grant contract No 2020247).

References:
[1] Ch. Ritzberger, E. Apel, W. Holand, A. Peschke, V. M. Rheiberger, "Properties and Clinical Application of Three Types of Dental Glass-Ceramics and Ceramics for CADCAM Technologies", Materials, pp. 3700-3713, 2010.
[2] L. Giner, M. Mercadé, S. Torrent, M. Punset, R. A. Pérez, L. M. Delgado, F. J. Gil,  "Double acid etching treatment of dental implants for enhanced biological properties". Journal of Applied Biomaterials and Functional Materials, pp. 83-89, 2018
[3] P. Schupbach, R. Glauser, S. Bauer, "Al2O3 Particles on Titanium Dental Implant Systems following Sandblasting and Acid-Etching Process", International Journal of Biomaterials, pp. 1-11, 2019