CC BY 4.0 · Eur J Dent
DOI: 10.1055/s-0043-1772569
Original Article

Flexural Strength of Two Multilayered and Monochromatic High Yttria Containing Zirconia Materials Following Different Sintering Parameters

Niwut Juntavee
1   Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
Apa Juntavee
2   Division of Pediatric Dentistry, Department of Preventive Dentistry, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
Chutikarn Jaralpong
3   Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
› Author Affiliations
Funding This study was funded by the Faculty of Dentistry, Khon Kean University, Ministry of Higher Education, Science, Research and Innovation, Royal Thai Government (grant number RTG02062563).


Objectives Sintering parameters influence the properties of zirconia. This study examined the effect of altering sintering temperature and time of monochrome and multilayer 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) on flexural strength.

Materials and Methods Three hundred specimens (width × length × thickness = 10 × 20 × 2 mm) were prepared from monolayer (ZX) and multilayer (ZM) 5Y-PSZ and randomly sintered at decreasing (TD: 1,450°C), regular (TR: 1,500°C), and increasing (TI: 1,550°C) sintering temperature, with extremely short (HE: 10 minutes), ultrashort (HU: 15 minutes), short (HS: 30 minutes), and regular (HR: 135 minutes) sintering time (n = 15/group). The precrack was induced on the tension side before testing for flexural strength (σ).

Statistical Analysis Analysis of variance and Tukey's test were used for significant differences of σ at p < 0.05. The microstructure and crystalline (monoclinic; m, tetragonal; t, cubic; c) phase were evaluated by scanning electron microscope (SEM) and X-ray diffractometer (XRD).

Results ZXTIHS indicated the highest σ for ZX (315.81 ± 18.91 MPa), whereas ZMTIHS indicated the highest σ for ZM (335.21 ± 36.18 MPa). There was no significant difference for σ between ZX and ZM (p > 0.05). Sintering zirconia at TI or HR indicated significantly higher σ than sintering at TD or TR or with HS, HE, or HU for both ZX and ZM (p < 0.05). There was no significant difference for σ between TRHR and TIHS, TIHU, and TIHE (p > 0.05). SEM indicated intergranular and transgranular fractures. XRD revealed predominately c- and t-phases and minor amounts of m-phase.

Conclusion Increasing sintered temperature with decreasing time offers acceptable strength to regular sintering. Raising sintering temperature with decreasing time is suggested to facilitate chairside restorative reconstruction.

Publication History

Article published online:
20 September 2023

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