IADR Abstract Archives
Damage Progression and Phase Transformation of Zirconia After Mouth-Motion Simulation
Objectives: To evaluate the damage progression and phase transformation of zirconia polycrystals subjected to a mouth-motion simulation.
Methods: A translucent zirconia (5Y-PSZ) and a control 3Y-PSZ were investigated. Disc-shaped specimens were produced for each ceramic by cutting pre-sintered CAD-CAM blocks, sintering and polishing to a 1 µm finish. Discs were adhesively bonded to a dentin-like substrate with a resin cement. Specimens were placed with 30o inclination in an electrodynamic machine, and subjected to a sliding-contact mouth-motion fatigue test, in distilled water at 2 Hz. A 200 N load was applied to the center of the ceramic disc through a zirconia spherical antagonist (r = 3.15 mm) for different number of cycles (n=4): 102, 103, 104, 105, 106 cycles. After the simulations, the ceramic surface was scanned and analyzed with an image processing software. Data were analyzed with two-way ANOVA and Tukey tests (α=0.05). SEM was used to characterize the surface and sub-surface damage. Crystallography phase determination was performed using Raman spectroscopy.
Results: The length and width of the scar increased with the number of cycles (p<0.001), regardless of the type of zirconia. 5Y-PSZ showed a more sever wear pattern than 3Y-PSZ. 5Y-PSZ had a larger density of cracks, which lead to dislodgement of zirconia grains, and resulted in a rougher surface. Distinct crystal phases were identified for the different types of zirconia ceramics and experimental conditions (Figure 1). Peaks of monoclinic phase were observed in 3Y-PSZ spectra.
Conclusions: After the mouth-motion simulation, 5Y-PSZ translucent zirconia had a more severe damage progression, while 3Y-PSZ showed signs of phase transformation.
Methods: A translucent zirconia (5Y-PSZ) and a control 3Y-PSZ were investigated. Disc-shaped specimens were produced for each ceramic by cutting pre-sintered CAD-CAM blocks, sintering and polishing to a 1 µm finish. Discs were adhesively bonded to a dentin-like substrate with a resin cement. Specimens were placed with 30o inclination in an electrodynamic machine, and subjected to a sliding-contact mouth-motion fatigue test, in distilled water at 2 Hz. A 200 N load was applied to the center of the ceramic disc through a zirconia spherical antagonist (r = 3.15 mm) for different number of cycles (n=4): 102, 103, 104, 105, 106 cycles. After the simulations, the ceramic surface was scanned and analyzed with an image processing software. Data were analyzed with two-way ANOVA and Tukey tests (α=0.05). SEM was used to characterize the surface and sub-surface damage. Crystallography phase determination was performed using Raman spectroscopy.
Results: The length and width of the scar increased with the number of cycles (p<0.001), regardless of the type of zirconia. 5Y-PSZ showed a more sever wear pattern than 3Y-PSZ. 5Y-PSZ had a larger density of cracks, which lead to dislodgement of zirconia grains, and resulted in a rougher surface. Distinct crystal phases were identified for the different types of zirconia ceramics and experimental conditions (Figure 1). Peaks of monoclinic phase were observed in 3Y-PSZ spectra.
Conclusions: After the mouth-motion simulation, 5Y-PSZ translucent zirconia had a more severe damage progression, while 3Y-PSZ showed signs of phase transformation.
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