Effect of Aging on Fracture Load and Reliability of Cemented Glass-Ceramics.

Purpose: To evaluate the influence of aging on the fracture load (Lf) and reliability of glass-ceramics after different etching protocols.

Materials and methods: Specimens were fabricated and divided according to the etching Ame (10% hydrofluoric acid [HF] for 20 seconds, 40 seconds, and 60 seconds). Etched surfaces were examined under microscopy. The ceramics were resin-cemented to a dentin analog material. Samples were split into two groups (n = 20 each) and tested after 24 hours (I) or stored in 37° water for 1 year (A). A compressive load (0.1 mm/minute) was applied to the samples unAl failure was detected by acoustic emission. The influence of aging on the Lf was tested by two-way ANOVA and Tukey tests (α = .05). The characteristic fracture load (L0) and Weibull modulus (m) values were calculated.

Results: Lithium silicate (LS) etching for 20 seconds resulted in the highest immediate Lf, which was significantly decreased after aging (P ≤ .05). Water storage had no effect on the Lf of glass-ceramic etched for 40 and 60 seconds (P > .05). For lithium disilicate (LD), the etching time had no significant effect on the immediate or aged Lf (P > .05). The Lf was significantly reduced after aging (A) for LD (P ≤ .05). Radial cracks were the predominant failure mode. Surface topography was more regular after lower etching times for LD and after higher times for LS.

Conclusions: After 1 year of water-assisted aging, the evaluated etching times had no influence on the load-bearing capacity and structural reliability of resin-bonded glass-ceramics.