Shear bond strength of two forms of opaque porcelain to the metal substructure

ObjectiveThis study was designed to compared the shear bond strength of two forms of opaque porcelain (paste and conventional powder/liquid) to metal substructure. Furthermore, the Scanning Electron Microscope (SEM) was used to determine the mode of failure.Materials and methodsSixty metal specimens were casted into Talladium alloy (Talladium Inc., Los Angeles, Calif.) and prepared to receive one of three commonly used porcelain systems in market; Vita VMK 95 (VITA Zahnfabrik H. Rauter GmbH & Co. KG), Ceramco 3 (Dentsply Ceramco, Burlington, NJ) and GC Initial MC (GC America Inc., Alsip, IL). Each material was tested in two forms; conventional powder/liquid form and paste form. Six different groups were established; the conventional porcelain groups were used as reference for comparison (n = 10). After 48-h storage in water at 37 °C, specimens were separated using Instron machine and the maximum force needed for separation was recorded and failure stress was calculated. Scanning Electron Micrographs (SEMs) were used to determine the mode of failure at ×1500. Statistical analysis was conducted.ResultsA significant effect of shear bond strength was found across materials, forms and interaction (P < .05). Vita VMK 95 had the highest shear bond strength (14.11 MPa ± 0.775) in the powder/liquid form, while Ceramco 3 showed the highest strength in the paste form (21.03 MPa ± 0.5). GC Initial MC showed the lowest strength in the conventional (8.24 MPa ± 0.097) and paste form (14.16 MPa ± 0.28). Paste opaque porcelain produced significantly higher shear bond strength than the conventional powder/liquid form with all combinations tested.ConclusionIt was concluded from this study that paste opaque porcelain can be used with confidence during fabrication of ceramometal restorations.