Influence of cement type on the bond strength of orthodontic bands to zirconia crowns.

BACKGROUND: This study evaluated the retentive strength and residual cement of orthodontic bands bonded to zirconia crowns using four cementation protocols: Glass-ionomer cement (GIC), Resin-modified glass ionomer cement (RMGIC), Transbond Plus Light Cure Band Adhesive without silane, and Transbond Plus with silane primer application. MATERIALS AND METHODS: Sixty zirconia crowns were divided into four groups (15 each) and cemented with the respective cements. Each crown was mounted on a resin-based tooth-like structure and secured to a universal testing machine. Orthodontic bands were adapted to the crowns, and forces were applied to measure retentive strength. After debonding, the remaining cement was assessed using the Adhesive Remnant Index (ARI). Specimens underwent thermocycling (5,000 cycles between 5 degrees C and 55 degrees C) to simulate oral conditions. RESULTS: The mean retentive strength was 1.23 MPa. Group 4 (Transbond Plus with silane) exhibited the highest strength (1.44 MPa), while group 1 (GIC) demonstrated the lowest (0.85 MPa). Cementation protocol significantly influenced retentive strength, with groups 2 (RMGIC) and 4 showing superior results to groups 1 and 3 (Transbond Plus without silane). CONCLUSION: The cement type and protocol employed significantly affect the shear-peel bond strength of orthodontic bands cemented to zirconia crowns. RMGIC and Transbond Plus, especially with silane, provide superior retention compared to GIC.