Presentation Blocks: 03-22-2018 - Thursday - 11:00 AM - 12:15 PM

Title: Effect of Hydrothermal Aging on Mechanical Properties of Ceramics Systems


Erica Gomes (Presenter)
University of Ribeirão Preto

Artur Marques, University of Ribeirão Preto
Stephanie Poole, University of Ribeirão Preto
Ricardo Ribeiro, University of São Paulo
Izabela Cristina Moris, University of Ribeirão Preto


Objectives: This study evaluated the surface roughness, flexural strength, and elastic modulus of ceramics systems subjected to hydrothermal aging.

Methods: Bar-shaped materials (2mm×4mm×16mm) of feldspathic ceramic (GF), lithium disilicate (GD), lithium silicate reinforced with zirconia (GS), conventional zirconia (GCZ), speed fire zirconia (GSZ), and monolithic zirconia (GMZ) were fabricated (n=13). The roughness and morphology of each group were evaluated through laser confocal microscopy before and after hydrothermal aging (the samples were autoclaved at 134°C, under 2 bars of pressure for 5h). Three-point bending flexural test was used to determine the flexural strength and elastic modulus. Fractography principles were employed to assess the fracture surfaces using optical and scanning electron microscopy (SEM). The effect of hydrothermal aging on the roughness was assessed using the linear mixed effects model and the Bonferroni test (p≤0.05), and the flexural strength and elastic modulus were analyzed by one-way ANOVA and the Bonferroni test (p≤0.05).

Results: Hydrothermal aging altered the surface roughness in the group GCZ (p≤0.05). GMZ revealed greater surface roughness, similar to GCZ and GSZ (p>0.05), but different from GF, GD, and GS (p≤0.05), which were statistically similar (p>0.05), both before and after hidrothermal aging. GCZ, GSZ, and GMZ revealed similar flexural strength (p>0.05) and higher to the other groups (p≤0.05). Statistical difference was observed between the groups GF, GD, and GS (p≤0.05). For the elastic modulus, GD, GS, GCZ, and GSZ were statistically similar (p>0.05); however, they differed from GF (p≤0.05) and GMZ (p≤0.05). SEM showed a higher frequency of compression curls for GF, GD, and GS than GCZ, GSZ, and GMZ.

Conclusions: Hydrothermal aging no changed the surface roughness of ceramics except for GCZ. Considering all the ceramics studied, the zirconias revealed better results, being that the monolithic zirconia indicated higher elastic modulus.