Retention of zirconia on titanium in two-piece abutments with self-adhesive resin cements

Abstract

Statement of problemTwo-piece abutments consisting of a prefabricated titanium luting base and a zirconia abutment are used widely in implant restorations. Straightforward and reliable procedures for bonding titanium and zirconia are necessary for ensuring low failure rates in such restorations. PurposeThe purpose of this in vitro study was to evaluate the tensile load of zirconia copings on prefabricated titanium abutments using 4 different self-adhesive resin cements. Material and methodsA total of 128 industrially manufactured partially yttria-stabilized zirconia ceramic copings were bonded to titanium abutments with a luting space of about 60 μm or 100 μm. The bonding surfaces were airborne-particle abraded with 50 μm alumina and cleaned ultrasonically. The zirconia copings were bonded with Panavia SA Cement Automix (SA), RelyX Unicem 2 Automix (RU), MaxCem Elite (ME), or SmartCem 2 (SC). Specimens from each cement group were randomly assigned to be stored either in distilled water (37°C) for 3 days or subjected to 37 500 thermocycles over 150 days. After debonding in tension, failure modes (adhesive or cohesive) were analyzed, and basic fuchsin dye penetration tests were performed using optical microscopy and scanning electron microscopy. Three-way ANOVA and Tukey HSD tests were used for statistical analysis (α=.05). ResultsThree-way ANOVA results determined that the luting resin used and the luting space had a significant effect (P≤.002), while the storage time did not have an overall effect (P>.05). The interaction between the luting resin used and storage time was significant (P<.001). After storage for 3 days, the retentive force of SA (1002 N) was highest, followed by that for RU (614 N), ME (550 N), and SC (346 N) (P≤.05); the forces for RU and ME were not significantly different (P>.05). However, after thermocycling, RU had the highest retentive force (848 N), followed by SA (646 N), ME (475 N), and SC (364 N) (P≤.05). Retentive forces for ME and SC were not significantly different (P>.05). The failure modes of the zirconia abutment surfaces were predominantly adhesive, while those of the titanium surfaces were mainly cohesive. The SA specimens showed the lowest dye penetration, followed by the RU, ME, and SC specimens. ConclusionsThe greatest mean retention was found with Panavia SA Cement Automix and RelyX Unicem 2 Automix with a luting space of 60 μm when bonding zirconia copings to titanium.