Estimation of the properties of zirconia-based ceramics crowns abraded with alumina particles
Dr n. med. Paulina Łagodzińska1, Prof. Beata Dejak1, Dr. Michał Krasowski2, Mr. Bartłomiej Konieczny2
1 Department of Prosthodontics, Department of General Dentistry, Medical University of Lodz, Łódź, Poland,
2 University Laboratory of Material Research, Medical University of Lodz, Łódź, Poland
Objectives
The aim of the study was to estimate the fracture resistance, allotropic changes and hardness of zirconia-based crowns after air-abrasion with alumina particles of different sizes.
Materials and Methods
Zirconia-based dental ceramics crowns and cuboid-shaped specimens (Ceramill Zi; AmannGirrbach AG, Koblach, Austria) were made using the CAD/CAM technology (CeramillMap 300, CeramillMind, CeramillMotion; AmannGirrbach AG). The specimens were air-abraded with 50 µm (G 50) or with 110 µm (G 110) alumina particles (Alustral; Omnident Dental HandelsgesellschaftmbH, Rodgau, Germany). The control group (G 0) was left untreated. The fracture resistance of the crowns was assessed in a universal testing machine (Zwick Z2.5 zwickLine; ZwickGmbH&Co.KG, Ulm, Germany). The presence of allotropic transformation within the ceramics surface was assessed with X-ray diffraction (PANalytical Empyrean; PANalytical B.V., EA Almelo, The Netherlands). The Vickers hardness was measured (HV1kp; Zwick/Roell ZHμ; ZwickRoell Indentec; ZwickGmbH&Co.KG). The Kruskal–Wallis one-way analysis-of-varianceby-ranks test was used to determine statistical significance (α = 0.05).
Results
The median fracture resistance of zirconia-based crowns (G 50) after air-abrasion with 50 µm alumina particles was 593 N (p < 0.001), the median hardness was 1734 HV1kp (p < 0.001), the 26% increase in the monoclinic phase volume was observed. The median fracture resistance obtained for crowns (G 110) abraded with 110 µm alumina particles was 632 N (p < 0.001), the median hardness was 1531 HV1kp (p = 0.05), 40% volume of the monoclinic phase was detected. In the control group (G 0) the median fracture resistance of crowns was 378 N (p < 0.001), the median hardness was 1531 HV1kp (p = 0.05), the monoclinic phase was undetectable.
Conclusions
Alumina air-abrasion of zirconia-based ceramics surface increases the fracture resistance of crowns and the volume of the monoclinic phase. The use of 50 µm alumina particle abrasion causes a significant increase of the Vickers hardness of zirconia surface.
This research was supported through a grant 502-03/2-148-03/502-24-005 provided by the Medical University of Lodz.