Influence of surface treatments on the bond strength of metal brackets to CAD/CAM materials and discoloration after various refinishing procedures : Scanning electron microscopy and atomic force microscopy study.


Tunca M., Degirmenci B.

Journal of orofacial orthopedics = Fortschritte der Kieferorthopadie : Organ/official journal Deutsche Gesellschaft fur Kieferorthopadie, no.2, 2022 (SCI-Expanded) identifier

Abstract

Purpose This study evaluated the shear bond strength (SBS) of a metal bracket bonded to three different computer-aided

design/computer-aided manufacturing (CAD/CAM) restoration materials pretreated with different surface treatments. In

addition, the surface topography and color change of the restorations after debonding with two different tungsten carbide

burs were examined.

Methods A total of 216 plates were cut from three different CAD/CAM blocks, each of which was divided into three

subgroups with different pretreatment methods: (1) acid etching, (2) sandblasting, and (3) laser irradiation. Incisor metal

brackets were bonded. The SBS test was performed, and the failure types were classified. Then, samples were randomly

divided into two subgroups according to the adhesive removal procedure to be used: a tungsten carbide bur with 12 blades

or 24 blades (n= 12). Color change was calculated based on the  E00, and surface morphology was evaluated via SEM

and AFM analysis.

Results The SBS data revealed that the type of CAD/CAM material and the applied surface treatment significantly

affected bond strength. The highest SBS values were detected for the Grandio Blocs (VOCO GmbH, Cuxhaven, Germany;

14.3± 4.4MPa), and the lowest was observed for Cerasmart (GC Europe, Leuven, Belgium; 12.0± 4.0MPa). The  E00

results demonstrated significant differences only as a result of the applied surface treatment. The  E00 value in all groups

was above the 1.77 threshold.

Conclusion CAD/CAM material types and surface treatments affected the bond strength, but the interactions of these

factors did not. The chosen surface treatment also significantly affected the  E00 after the polishing was done.