Comparative Evaluation of Orthodontic Bonding Systems for Ceramic Brackets on Zirconia Crowns: A Shear Bond Strength and Adhesive Remnant Index Study

Background The purpose of this research was to compare the adhesive residual score/adhesive remnant index (ARI) and shear bond endurance between the two orthodontic bonding systems for zirconia surface bonding: Self-etch (Scotchbond Universal) and total-etch (Transbond XT). Materials and Methods Color-coded acrylic blocks embedded with zirconia slabs were prepared, and the orthodontic brackets (ceramic) were bonded using either the total-etch or self-etch system. Group 1, represented by pink-colored blocks ( N = 12), accommodated 12 zirconia surfaces using the total-etch system, while Group 2, represented purple-colored blocks ( N = 12), also housed zirconia surfaces using the self-etch system. The shear bond strength was evaluated using an Instron Universal Testing Machine, and ARI scoring was done upon debonding. The statistical software SPSS was used for the analyses. Results The average bonding strength for the Scotchbond Universal etch system was 6.21 ± 0.76 MPa, while for the total-etch system, it was 5.59 ± 1.37 MPa. The ARI scores revealed that 83% of surfaces bonded with the self-etch system had no adhesive residue (ARI score 0), compared to 66% for the total-etch system. Conclusion The self-etch bonding agent demonstrated superior bond strength (6.2 MPa) compared to the total-etch system (5.6 MPa). Furthermore, it exhibited better ARI scores, indicating minimal adhesive residue. These findings suggest that the self-etch system is preferable for bonding ceramic brackets to zirconia crowns, offering improved bonding efficacy and ease of clean-up.