Selective infiltration-etching technique for a strong and durable bond of resin cements to zirconia-based materials.

STATEMENT OF PROBLEM: Establishing a strong and a stable adhesive bond between yttrium, partially stabilized, tetragonal zirconia, polycrystal materials (Y-TZP) and resin luting agents has proven to be difficult using conventional surface roughening and coating methods.
PURPOSE: The purpose of this study was to evaluate the zirconia-resin bond strength and durability using a selective infiltration-etching technique.
MATERIAL AND METHODS: Seventy-two Y-TZP discs (19.5 x 3 mm) were airborne-particle abraded with 110-mum aluminum oxide particles and divided into 4 groups (n=18). One test group received the selective infiltration-etching surface treatment. Three commercial adhesive systems (Panavia F 2.0, RelyX ARC, and Bistite II DC) were used to bond the airborne-particle-abraded zirconia specimens to preaged restorative composite resin discs (Filtek Z250). Panavia was used to bond the selective infiltration-etched specimens. The bonded specimens were cut into microbars (6 x 1 x 1 mm), and a microtensile bond strength test (MTBS measured in MPa) was conducted immediately, after 1 week, 2 weeks, 3 weeks, and after 1 month of water storage (5 microbars/disc/time interval/group, n = 450 microbars/group). Scanning electron microscopy was used to examine the fractured microbars. The density (g/cm(3)) and the 4-point flexure strength (MPa) of the selective infiltration-etched and airborne-particle-abraded specimens were measured to evaluate the effect of selective infiltration etching on the structural integrity of the Y-TZP specimens. A repeated measures ANOVA with 1 within-subjects factor (time, 5 levels) and 1 between-subjects factor (technique, 4 levels) was used to analyze the data (alpha=.05). Pairwise comparisons were made using the Bonferroni post hoc test.
RESULTS: There were significant differences in the initial MTBS values (MPa) between the 4 bonding techniques (P<.001). Airborne-particle-abraded specimens bonded with either Panavia F 2.0, RelyX ARC, or Bistite II DC resulted in a mean (SD) bond strength of 23.3 (2.4), 33.4 (2.1), 31.3 (2.8) MPa, respectively, while the highest bond strength of 49.8 (2.7) MPa was achieved for the selective infiltration-etched specimens bonded with Panavia F 2.0. There was a significant interaction between water storage time and the bonding technique (P<.001) as reduction in MTBS values was observed with time, except for the specimens bonded with Panavia (selective infiltration-etched and airborne-particle-abraded specimens). Additionally, the observed failure mode was primarily cohesive for the selective infiltration-etched specimens, in contrast to the other groups, which showed primarily an interfacial failure.
CONCLUSIONS: For the materials used in this study and under the same testing conditions, selective infiltration etching is a reliable method for establishing a strong and durable bond with zirconia-based materials.