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

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.

The purpose of this study was to evaluate the zirconia-resin bond strength and durability using a selective infiltration-etching technique.

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.

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.

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.