Properties of Speed-sintered Monolithic Zirconia Ceramics
Objectives: To evaluate the optical and mechanical properties, microstructure and aging behavior of speed-sintered monolithic zirconia. Methods: Sintering in a SpeedFire furnace (‘SF’; Dentsply Sirona) of 5Y-TZP Katana STML (Kuraray Noritake; sintering time/temperature: 30min/1560°C) and 3Y-TZP CEREC Zirconia (Dentsply Sirona; sintering time/temperature: 15min/1578°C) blocks was compared to sintering in a conventional furnace (Nabertherm, Germany) of Katana STML (sintering time/temperature: 2h/1550°C) and 3Y-TZP inCORIS (Dentsply Sirona; sintering time/temperature: 2h/1510°C). Translucency Parameter (TP) and Contrast Ratio (CR) were measured with a spectrophotometer (SpectroShadeTM MICRO, MHT Optic Research) (n=6/group). Zirconia-phase composition was characterized using XRD and SEM. The indentation fracture toughness (n=10), biaxial strength (n=20) and Vickers hardness (n=10) of the sintered ceramics were assessed. Aging behavior was evaluated by measuring tetragonal-to-monoclinic phase transformation after accelerated hydrothermal aging in steam at 134°C (n=2); the transformation curves were fitted by the Mehl-Avrami-Johnson (MAJ) equation. Statistical analysis involved one-way ANOVA and post-hoc Tukey’s HSD test (α=0.05). Results: TP of Katana STML, sintered in both ways, was significantly higher than for CEREC Zirconia and inCORIS. XRD of Katana STML, sintered in both ways, confirmed higher cubic phase (≈50wt%) and Y2O3 (≈4.5mol%) in t-ZrO2 phase content, as compared to CEREC Zirconia (7.9wt%) and inCoris (18.8wt%), both containing ≈3mol% Y2O3 in t-ZrO2 phase content. SEM revealed the largest grain sizes for speed-sintered Katana STML. Although no statistical difference in hardness was measured, CEREC Zirconia revealed higher fracture toughness, biaxial strength and Weibull characteristic strength than speed-sintered Katana STML. Katana STML, sintered in both ways, revealed similar hydrothermal aging behavior and stronger aging resistance than CEREC Zirconia and inCORIS. Conclusions: Speed-sintered monolithic zirconia revealed similar optical properties and hydrothermal aging behavior as conventionally sintered monolithic zirconia grades. As expected, speed-sintered Katana STML revealed lower mechanical properties than CEREC Zirconia.
Division:Continental European and Scandinavian Divisions Meeting
Meeting:2019 Continental European and Scandinavian Divisions Meeting (Madrid, Spain) Location:Madrid, Spain
Year: 2019 Final Presentation ID:0284 Abstract Category|Abstract Category(s):Dental Materials 1: Ceramic-based Materials
Authors
Cokic, Stevan
( KU Leuven (University of Leuven)
, Leuven
, Belgium
)
Zhang, Fei
( KU Leuven (University of Leuven)
, Leuven
, Belgium
)
Van Meerbeek, Bart
( KU Leuven (University of Leuven)
, Leuven
, Belgium
)
Vleugels, Jef
( KU Leuven (University of Leuven)
, Leuven
, Belgium
)