A Polymer-Infiltrated Ceramic as Base Adherent in an Experimental Specimen Model to Test the Shear Bond Strength of CAD-CAM Monolithic Ceramics Used in Resin-Bonded Dental Bridges

Abstract

Traditional load-to-failure tests fail to recreate clinical failures of all-ceramic restorations. Experimental fabrication, similar to prosthetic laboratory and clinical procedures, best predicts future clinical performance. A hybrid ceramic adherend, mechanically similar to a human tooth, was tested by comparing the shear bond strength (SBS) and fracture mode of four restorative materials adhered with a dual-cure adhesive cement. Surface energy, shear bond strength (SBS), and fracture mode were assessed. Vita Enamic (ENA), Vita Suprinity (SUP), Vita Y-TPZ (Y-ZT), and a nanohybrid composite (RES) (control group) cylinders, adhered with RelyX Ultimate to ENA blocks were assembled in experimental specimens simulating a 3-unit resin-bonded dental bridge. The ENA adherend was ground or treated with 5% hydrofluoric acid for 60 s. Monobond Plus was used as the coupling agent. Mean shear stress (MPa) was calculated for each group. Forest plots by material elaborated after calculating the difference in means and effect size (α = 0.05; 95% CI; Z-value = 1.96) revealed significant differences in the shear force behavior between materials (p < 0.01). RES (69.10 ± 24.58 MPa) > ENA (18.38 ± 8.51 MPa) > SUP (11.44 ± 4.04 MPa) > Y-ZT (18.48 ± 12.12 MPa). Y-ZT and SUP exhibited pre-test failures. SBS was not related to surface energy. The failure mode in the Y-ZT group was material-dependent and exclusively adhesive. ENA is a potential adherend for dental materials SBS tests. In this experimental design, it withstood 103 MPa of adhesive stress before cohesive failure.