. 2019 Nov 14;56(1):1–23. doi: 10.1016/j.jdsr.2019.09.002

Table 3.

Studies investigating mechanical properties of monolithic zirconia specimens/crowns after hydrothermal aging (steam autoclave and boiled water/artificial saliva). Studies are presented in ascending chronological order.

Authors	Zirconia system	Test type /Aging test	Flexural strength change	m-ZrO₂ content
Specimens
Alghazzawi et al. (2012) [118]	− 5.3 mol% Y₂O₃	Flexural strength (piston-on-three balls), crosshead-speed 1 mm min⁻¹	No significant change	Control = 2.4 ± 0.6%
Alghazzawi et al. (2012) [118]	− 5.3 mol% Y₂O₃	Boiled: 100 °C, 7 days, artificial saliva	No significant change	Aged = 21.0 ± 2.0%
Dehestani and Adolfsson (2013) [125]	- 3Y-TZP	Flexural strength (4-Point Bending)	No significant change. 3Y-TZP containing materials showed the highest strength	Values cannot be extrapolated. 12Ce-TZP: almost no change in m-ZrO₂, 10Ce-TZP: m-ZrO₂ up to 90% and 3Y-TZP: m-ZrO₂ ˜ 50% after 32 days.
Dehestani and Adolfsson (2013) [125]	- 3Y-TZP/Al₂O₃	Aging in water at 90 °C for 2, 4, and 6 months
	- 12Ce-TZP/Al₂O₃
	- 10Ce-TZP /Al₂O₃
	All composites had 70/30 vol zirconia/alumina
Adabo et al. (2015) [122]	- ICE Zirkon	Flexural strength (piston-on-three balls), crosshead-speed 1 mm min⁻¹	No significant change	No values are reported, however all specimens presented increase
	- Prettau	Steam autoclave: 120 °C, 2 kg/cm², 8 h
	- Prettau Anterior	Steam autoclave: 120 °C, 2 kg/cm², 8 h
Alghazzawi et al. (2015) [120]	- Lava Plus (Lav)	Flexural strength (3-point bending), crosshead speed 0.5 mm min⁻¹	Coupons:	N/A
Alghazzawi et al. (2015) [120]	- Argen HT (Arg)	Steam autoclave: 134 °C, 0.2 MPa, 50 hours	- increase for Arg, Zir and Zen
	- Zirlux (zir)		- no significant change for Lav, Brux and DDB
	- BruxZir (Bru)
	- Zenostar (Zen)
	- DDBioZX² (DDB)
Pereira et al. (2016) [124]	- Zirlux FC	Flexural strength (piston-on-three balls), grinded specimens (diamond burs, water cooling), crosshead speed 1 mm min⁻¹	Significant increase of characteristic strength for control, no significant change for the rest		Before aging	After aging
Pereira et al. (2016) [124]		Steam autoclave: 134 °C, 2 bars, 20 h		Control	0%	67.97%
				Fine grinded	9.49%	38.74%
				Coarse grinded	9.66%	42.76%
Stawarczyk et al. (2016) [119]	- Zenostar	Flexural strength (4-Point Bending), crosshead-speed 1 mm min⁻¹	No significant change. All monolithic showed lower flexural strength values compared to the conventional zirconia.	N/A
Stawarczyk et al. (2016) [119]	- DD Bio ZX2	Steam autoclave: 134 °C, 2.3 bars, 5 h
	- Ceramill Zolid
	- InCoris TZI
	- Ceramill ZI
Flinn et al. (2017) [121]	- Prettau	Flexural strength (4-point bending), crosshead speed 0.5 mm min⁻¹	Significant reduction only for Prettau and BruxZir		Before aging (%)	After aging for 200h (%)
Flinn et al. (2017) [121]	- BruxZir	Steam autoclave: 134 °C, 0.2 Mpa, 5, 50, 100, 150, and 200 h		Prettau	2.90 ± 0.34%	76.1 ± 0.64%
	- Katana HT13			BruxZir	2.69 ± 0.18%	76.0 ± 0.26%
	- Katana ML			Katana HT	4.6 ± 0.19%	35.8 ± 0.80%
	- Katana ML			Katana ML	3.57 ± 0.35%	33.2 ± 1.1%
Guilardi et al. (2017) [123]	- InCeram YZ	Flexural strength (piston-on-three balls), fine and coarse grinded specimens (diamond burs under water cooling), crosshead speed 1 mm min⁻¹	No significant change. Grinding affected positively the material’s aging sensitivity.		Before aging (%)	After aging (%)
Guilardi et al. (2017) [123]		Steam autoclave: 134 °C, 2bars, 20 h		Control	0 ± 0.0	76.1 ± 0.64
				Fine grinding	9.70 ± 0.89	24.42 ± 3.45
				Coarse grinding	13.07 ± 1.5	40.94 ± 1.61
Khayat et al. (2017) [91]	Tizian Blank Translucent	Flexural strength (piston-on-three balls), crosshead-speed 0.5 mm min⁻¹	Grinding significantly increased roughness and decreased strength. Grinding and polishing had no significant effect on flexural strength. Rough zirconia was more prone to aging.	N/A
Khayat et al. (2017) [91]	Tizian Blank Translucent	Steam autoclave: 134 °C, 200 kPa, 3 h
		Specimens were:
		- grinded
		- grinded and polished (polishing kit 1)
		- grinded and polished (polishing kit 2)
		- glazed
Munoz et al. (2017) [99]	- Prettau Anterior	Flexural strength (piston-on-three balls), crosshead-speed 1 mm min⁻¹	Significant difference for Pretau Anterior, but not for the others	Prettau Anterior	Pretau	ICE Zirkon
Munoz et al. (2017) [99]	- Prettau	Steam autoclave: 134 °C, 0.2 MPa, 8 h		0%	39.71%	24.89%
	- ICE Zirkon	Steam autoclave: 134 °C, 0.2 MPa, 8 h		0%	39.71%	24.89%
Sulaiman et al. (2017) [101]	- Prettau (PSZ)	Flexural strength (3-point bending test), crosshead speed 0,5 mm min⁻¹.	No significant effect of either FSZ or PSZ	N/A
Sulaiman et al. (2017) [101]	- Prettau Anterior (FSZ)	Steam autoclave: 125 °C, 200 kPa, 8 h
	- ICE Zircon (PSZ)	Steam autoclave: 125 °C, 200 kPa, 8 h
Camposilvan et al. (2018) [84]	- Aadva ST	Flexural strength (piston-on-three balls)	No significant change	Arithmetic values cannot be extrapolated from the graph. NT and ML showed no transformation at all, while ST and EI presented high amounts of m-ZrO₂ (˜45%)
Camposilvan et al. (2018) [84]	- Aadva EI	Steam autoclave: 134 °C, 2 bar, 0, 2, 6, 18, 54 h
	- Aadva NT
	- Katana UT

Crowns
Alghazzawi et al. (2015) [120]	- Lava Plus (Lav)	Fracture toughness, axially oriented molar crowns, crosshead speed 0.5 mm min⁻¹	- no significant effect	N/A
	-Argen HT (Arg)	Steam autoclave: 134 °C, 0.2 MPa, 50 hours
	- Zirlux (zir)
	- BruxZir (Bru)
	- Zenostar (Zen)
	- DDBioZX² (DDB)
Nakamura et al. (2015) [126]	Lava Plus	Fracture toughness, axially oriented molar crowns, crosshead speed 0.5 mm min⁻¹	Significant decrease up to 50 h of aging and no change thereafter.	70% after 50 h of aging and no increase thereafter
		Combination of cycling loading (50, 300 N, 240,000 cycles, water) and autoclave treatment for 100 h	Cycling loading had no effect on strength.
		Steam autoclave: 134 °C, 0.2 Mpa, 0, 10, 50, 100 h
Bergamo et al. (2016) [128]	- Ceramill Zolid	Fracture test, molar crowns: axial load, crosshead-speed 1 mm min⁻¹	No significant change	Control: 4%
		Steam autoclave: 122 °C, 2 bars, 1 h		Steam autoclave: up to 4.5%
Leone et al. (2016) [127]	- GC Initial Zr:	Flexural strength (piston-on-three balls), crosshead-speed 1 mm min⁻¹	Significant change for ST. The presence of glaze had a protective effect. The mechanical properties of cubic crowns (UHT) were lower than for tetragonal ones.	No values are reported, complete absence of hydrothermal degradation for UHT.
	Ultra high translucency (UHT)	steam autoclave 134 °C, 2 bars, for 2, 6, 18 and 54 h
	High translucency (HT)
	Standard translucency (ST)
Prado et al. (2017) [92]	Zirlux FC	Flexural strength, crosshead speed 1 mm min⁻¹	Low temperature degradation led to an increase in flexural strength	control group: 58.17%
		Aging: Grinding with extra-fine diamond burs (grit size 30 μm) under constant water-cooling, autoclave storage at 134 °C / 2 bar / 20h		ground samples: 9.25%
				ground + low temperature degradation: 16.13
Pereira et al. (2018) [82]	Katana YSZ ceramics used:	Flexural strength (piston-on-three balls), crosshead-speed 1 mm min⁻¹, step stress fatigue approach, autoclave aging at 134 °C / 2 bars pressure/20 h	No significant change for STML and UTML.	- Increase for ML
	– ML/HT		Significant increase for ML.	- No impact on STML and UTML
	- STML
	- UTML
Almansour et al. (2018) [83]	- Lava Plus HT	Flexural strength (piston-on-three balls), crosshead-speed 0.5 mm min⁻¹, fatigue (chewing simulator with 250,000 cycles / frequency of 1.6 Hz / load of 200 N), accelerated artificial aging at 3500 cycles (two water baths, 5 °C and 55 °C. 60 sec per cycle in 5 °C bath, 10 sec to transfer samples to 55 °C bath, 20 seconds in 55 °C bath and 10 seconds to transfer back to 5 °C bath	before: Ceramill ZI (935.3 ± 47.1 MPa)>Copran Zr-i Monolithic HT (847.8 ± 20.7 MPa)>Lava Plus (732.4 ± 25.5 MPa)>Ceramill Zolid White (685.7 ± 32.6 MPa)	Not evaluated
	- Ceramill Zolid White HT		after: Copran Zr-i Monolithic HT (777.5 ± 21.2 MPa)>Ceramill ZI (668.0 ± 20.1 MPa)>Lava Plus (666.4 ± 21.1 MPa)>Ceramill Zolid White (575.0 ± 36.3 MPa)
	- Copran Zr-i Monolith HT
	- Ceramill ZI-LT
Dapieve et al. (2018) [94]	- Zirlux FC2	Flexural strength, step-stress fatigue, 20 Hz and minimum stress of 10 MPa, 5000 cycles under 200 MPa + incremental steps of 25 MPa for 10,000 cycles from 400 MPa to complete failure	Fatigue strength change: aging increased the fatigue strength for ground groups, it did not affected the as-sintered groups	Before aging: Control Autoclaved samples: 56.75%, Ground + Autoclaved: 30.63%
	- Ardent	Aging protocol: Grinding with coarse diamond burs (#3101 G – grit size 181 μm) in a slow-speed motor under constant water-cooling (≈30 mL/min). Dry storage in sealed vessel for 2 years (mean temperature of 27 °C and mean humidity of 80% + autoclave LTD / 134 °C / 2 bar / 20 h		After: Control Autoclaved: 75.27%. Ground + Autoclaved: 40.14%