Bond strength of metal and ceramic brackets bonded to the surface of cad/cam blocks

Background: CAD/CAM crowns or veneers have been frequently founded in patientsin needed of bracket bonding and there is no conclusive evidence regarding the ideal protocol for bonding brackets to ceramic or provisional materials surfaces. Aims: This study evaluated the bond strength and the adhesive remnant index of metallic (Victory Series, 3M Unitek) and ceramic (Clarity, 3M Unitek) brackets bonded to the surface of different computer-aided design/computer-aided manufacturing (CAD/CAM) blocks using Transbond XT (3M Unitek) adhesive. Settings and Design: In vitro study. Methods and Material: Three types of CAD/CAM materials, namely feldspathic ceramic (FEL), lithium disilicate ceramic (LDC), and acrylic resin (AR) were randomly divided into six groups (n=12) including G1 (metallic brackets bonded to FEL ceramic blocks), G2 (metallic brackets bonded to LDC blocks), G3 (metallic brackets bonded to AR blocks), G4 (ceramic brackets bonded to FEL ceramic blocks), G5 (ceramic brackets bonded to LDC blocks), and G6 (ceramic brackets bonded to AC blocks). Subsequently, a bond strength test was carried out between the brackets and the blocks. The adhesive remnant index was also assessed. Statistical analysis used: Analysis of variance (ANOVA) followed by Tukey’s post-hoc test. Results: Groups G3 and G6 showed the highest bond strengths when compared with the other groups and the highest percentage of adhesive failures (91.66% and 91.35%, respectively). The G1 group had the lowest bond strength values. Conclusions: Bonding of metallic and ceramic brackets to CAD/CAM acrylic resin blocks showed greater bond strength than bonding of brackets to ceramic blocks. Bonding to acrylic resin was associated with a higher percentage of adhesive fractures, which is favorable for bracket removal.