The impact of different surface treatments on the shear bond strength of orthodontic metal brackets applied to different CAD/CAM composites

Background To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different CAD/CAM composites treated with different surface treatments. Material and Methods Specimens of two CAD/CAM composites were obtained of Lava Ultimate (LU; n=60) and Brilliant Crios (BC; n=60) which were randomly separated into six subgroups (n=10) according to the surface treatment: control (CTL); sandblasting (SB); sandblasting and silane (SBSL); hydrofluoric acid (HF); hydrofluoric acid and silane (HFSL); and Monobond Etch&Prime (MEP). The mandibular central incisor metal brackets were bonded with a light-cure adhesive. The SBS data were analyzed using the two-way analysis of variance and Turkey's test, while the adhesive remnant index (ARI) by the Kruskal-Wallis, all the significance was set at 5%. Results A higher SBS was found for BC in comparison with LU (p 0.05) showed a higher SBS, which was followed by MEP and SB (p> 0.05), all in comparison with CTL (p 0.05). Significant differences were detected between CTL to HF, and HF to MEP, as well. Conclusions The SBS is highly affected by the surface treatment and also by the CAD/CAM composite. The surface treatment improves the SBS and should be encouraged when orthodontic brackets are bonded to CAD/CAM composites. Key words:CAD/CAM composite resin, brackets, shear bond strength, surface treatment, bonding.