Bonding of different resin luting materials to composite, polymer-infiltrated and feldspathic ceramic CAD/CAM blocks

This in-vitro study aimed to evaluate the micro-tensile bond strength (μTBS; MPa) of a highly-filled flowable composite (G-aenial Universal Flo; GC, UF), a micro-hybrid composite (G-aenial; GC, C) and dual-cure resin cement (Linkforce; GC, LF) used as luting materials to composite (Cerasmart; GC, CS), polymer infiltrated-ceramic (Enamic; Vita, VE) and feldspathic ceramic (Cerec; Sirona, CE) CAD/CAM blocks with and without additional universal adhesive (G-Premio Bond; GC, UA) application. CAD/CAM blocks (n:3) from each material were cut into slabs of 4 mm thickness and were divided into two groups according to the presence or absence of UA application. Slabs from VE, CS and CE were luted together with UF, C and LF. Following storage in distilled water at 37 °C for 24 h, µTBS (n:24 with UA; n:24 without UA, Instron Inc) was evaluated and analyzed with three-way ANOVA and post hoc Tukey’s tests (p < 0.05). µTBS was significantly influenced by the type of CAD/CAM material (p = 0.0001), resin luting material (p = 0.0001) and UA application (p = 0.0001). VE + UF resulted in significantly the highest µTBS with and without UA (p < 0.05). UF and LF exhibited similar µTBS to CS and CE with and without UA (p > 0.05), while UA significantly increased bonding in the VE + C, CS + C and CE + C groups (p < 0.05). The bonding performance of the highly filled flowable composite to VE, CS and CE was similar or significantly higher than that of the micro-hybrid composite and dual-cure resin cement with and without UA application. Additional UA application improved bonding of the micro-hybrid composite to all CAD/CAM materials.