Objective: To investigate the shear bond strength and failure mode of a resin composite bonded to base metal alloy and zirconia frameworks that have been subjected to tribochemical treatments.
Methods: Disk-shape specimens from a Cr-Co alloy and fully sintered zirconia (Group Z, n=20) were metallographically polished up to 1000 grit-size SiC and covered with a masking tape, leaving a free circular area (2mm). The specimens were randomly selected into two subgroups (M1, M2 and Z1, Z2, n=10 respectively). M1 and Z1 were sandblasted with CoJet (3M ESPE) and M2, Z2 with the experimental SilJet (Danville Materials) under the following conditions: 5 mm distance, 90° angle, 5 s blasting at 3 bar pressure. All surfaces received a silane treatment and then restored with a flow-composite and cured for 30s. For Group M, prior to composite placement, a thin opaque layer (0.2mm) was applied and cured as above. All the specimens were stored in water (5d/37°C) and then thermo-cycled (x3000, 5/55°C, 10s dwell & 5s transfer times). Bond strength was determined under shear loading (SBS) at a crosshead speed of 0.5 mm/min. Results were statistically analysed with One-Way ANOVA at p=0.05. Failure mode analysis was evaluated under a stereomicroscope.
Results: The results of SBS were (MPa, mean/sd): M1:22.9 (2.5), M2:26.1 (2.0), Z1:12.1 (2.7), Z2:14.4 (2.1). M2 and Z2 showed significantly higher values from M1 and Z1 groups respectively. Failure mode in M group was mainly mixed (50%) and adhesive (30-40%), whereas in Z group was mainly adhesive (70-80%).
Conclusions: Significant differences were found between the two tribochemical treatments tested. Both treatments were more effective on the Cr-Co alloy than on zirconia.