Bond Strength Stability of Self-adhesive Resin Cement to Etched Vitrified Yttria-stabilized Tetragonal Zirconia Polycrystal Ceramic After Thermomechanical Cycling.

The purpose of this study was to evaluate the influence of thermomechanical cycling on the bond strength stability of self-adhesive resin cement to vitrified yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic. Y-TZP ceramic blocks were divided into four groups according to the surface treatments: AS, as sintered; SB, sandblasted with 50-mum Al(2)O(3) particles; LG, vitrification with a low-fusing glaze and etching with 10% hydrofluoric acid; and HC, vitrification with a ceramic liner and etching with 10% hydrofluoric acid. Lithium disilicate ceramic blocks etched with 10% hydrofluoric acid for 20 seconds (EM) were also tested. Blocks of resin composite were cemented on the ceramic block surfaces using a self-adhesive resin cement. Half of the blocks from each group were cut into beams and submitted to microtensile bond strength (muTBS) testing after immersion in water at 37 degrees C for 24 hours and the other half after mechanical (1,200,000 cycles, 98 N, 2.5 Hz) and thermal (10,000 cycles, 5-55 degrees C, 30-second dwell time) cycling (TMC). Data were analyzed using one-way analysis of variance, Tukey's honest significant difference post hoc test, and Student t-test (alpha=0.05). After 24 hours, EM and LG presented similar and the highest muTBS, whereas AS showed the lowest muTBS (p<0.05). After TMC, EM presented the highest muTBS, followed by LG (p<0.05). Only EM and LG maintained the stability of muTBS after TMC (p>0.05). The bonding to Y-TZP ceramic vitrified with a low-fusing glaze withstood thermomechanical cycling.