Fatigue survival rate of resin-bonded zirconia-based ceramics after different surface treatments.

OBJECTIVES

To assess the fatigue survival rate of zirconia-based ceramics (3Y-TZP and 5Y-PSZ) bonded to resin-based cement after various surface treatments, testing the hypotheses that the surface treatments do not affect the fatigue survival rate and that 3Y-TZP has higher fatigue survival than 5Y-PSZ when bonded to a resin-based cement.

METHODS

Disc-shaped specimens were made from 3Y-TZP (Vita YZ HT) and 5Y-PSZ (Vita YZ XT) monolithic zirconia blocks. The specimens were randomly assigned to six groups according to material and surface treatment: as milled (3Y-None and 5Y-None), silica coating (3Y-Si and 5Y-Si), and airborne-particle abrasion using alumina particles (3Y-AP and 5Y-AP). All zirconia structures were bonded to a fiber-reinforced epoxy resin base (G10). Fatigue test was performed under a 120 N load at a frequency of 3 Hz, and it was discontinued for failure assessment after 10, 10, 5 × 10, 10, and 1.5 × 10 cycles. Presence of any failure was recorded. Representative samples were evaluated under scanning electron microscopy, and the chemical composition was assessed using energy-dispersive spectroscopy (EDS). Fatigue data were analyzed using the Kaplan-Meier (log-rank) and Holm-Sidak methods. Failure modes were determined using fractography principles and statistically assessed using chi-square test.

RESULTS

Surface treatments showed significantly different survival curves (p < 0.001) for 5Y-PSZ, but no difference for 3Y-TZP (p = 0.54). Silica coating resulted in a significant difference behavior (p < 0.001) between 3Y and 5Y ceramics. Yet, AP (p = 0.70) and None (p = 0.38) did not influence the survival rates for both ceramics. No significant difference in failure modes was observed among experimental groups (p = 0.30).

SIGNIFICANCE

The fatigue survival rate of resin bonded 5Y-PSZ was negatively affected by silica coating.