Translucency of monolithic and core zirconia after hydrothermal aging

Figures & data

Table 1. Materials used in the study.

Material type	Material commercial name	Manufacturer	Composition wt %	Batch number
Y-TZP for monolithic  crown construction	Zirkonzahn Prettau Y-TZP pre-sintered blocks	Zirkonzahn GmbH, Bruneck, Italy	Main components: ZrO2 (92.27) Y2O3 (4–6).Traces: Al2O3 (<1), SiO2 (0.02), Fe2O3 (0.01) and Na2O (0.04).	ZRAD8061
Y-TZP for core construction	Lava frame Zirconia pre-sintered blocks	3M-ESPE, St. Paul, MN	Main component: ZrO2 (92.27), Y2O3 (4.98).Traces: Al2O3 (0.43), SiO2 (0.21), HfO2 (1.58).	68591

Figure 1. X-ray diffraction patterns of monolithic zirconia: (a) before aging, (b) after aging with monoclinic (m) peaks.

Figure 2. X-ray diffraction patterns of core zirconia: (a) before aging, (b) after aging with monoclinic (m) peaks.

Table 2. Volumetric monoclinic phase content of aged Y-TZP (V_m).

Y-TZP Type	Vm (%)
Monolithic	25.0
Core	18.0

V_m, monoclinic volume after aging.

Table 3. Average grain particle size for both Y-TZP types before and after aging.

Y-TZP type		Average crystal size (nm)
Monolithic	Before aging	49.682
	After aging	30.243
	Core	Before aging	34.915
After aging		22.612

Table 4. Student’s t-test of translucency for both materials before and after aging.

Material	Translucency				T value	p value
	Before		After
	Mean	SD	Mean	SD
	Monolithic	16.4	0.316	13.35			0.158	19.3	0.0001*
Core	9.38	0.395	7.05	0.261	8.53	0.0001*
T value	31.3		45.9
p value	0.0001*		0.0001*

* significant difference at P value ≤ 0.05.

Figure 3. SEM images of monolithic Y-TZP before aging showing the less dense structure before aging (magnification 5000).

Figure 4. SEM images of core Y-TZP before aging showing the more dense structure before aging (magnification 5000).