Effect of acidic surface treatment on shear bond strength of composite cement to zirconia: a comparative study

This research assessed the effect of acidic surface treatment in two different approaches involving airborne-particle abrasion (APA) surface treatment, relative to APA by itself, on the shear bond strength (SBS) of composite cement adhered to zirconia. Sixty cubes of 5 mol% yttria-stabilized zirconia (10 × 10 × 8 mm) were created and categorized into three groups (n = 20 each): APA Group, treated with 50 µm Al₂O₃ APA; APA + ZE 30 Group, underwent the same treatment as APA Group, followed by a 30 min ultrasonic application of Zircos-E etchant (ZE); and APA + ZE 120 Group, which received the same treatment as APA Group, followed by ZE for 120 min. SEM analyses were performed on three samples for each surface treatment. Each group was subdivided (n = 10 each) to receive either self-adhesive composite cement (RelyX U200) or MDP-containing primer (G-Multi primer) combined with BisGMA-based composite cement (G-CEM LinkForce). Composite cement cylinders were cast onto zirconia samples utilizing a mold (Ø4 × 3 mm). Samples were kept in an incubator at 37ºC with purified water for 24 h. An SBS test was subsequently performed using a universal testing machine (0.5 mm/min crosshead speed). Both ZE treatment groups demonstrated a significant level of difference compared to APA (p < 0.001), while there was no notable variation between the ZE treatment groups (p = 0.841). Moreover, there was no meaningful difference observed between the two varieties of composite cements (p > 0.05). Ultimately, SEM examinations of both ZE groups showed pits and porosities. Using acidic surface etchant is promising as an additional to APA for increasing SBS of composite cement to zirconia.