Microshear Bond Strengths of Nine CAD/CAM Restorative Materials

Objectives: To evaluate the microshear bond strength (µSBS) of a universal adhesive and an MDP-containing silane applied on indirect restorative materials.
Methods: Nine CAD/CAM materials were selected: 1) LAVA Ultimate (LAV, 3M Oral Care); 2) Brava (BRV, FGM); 3) VIPIBlock (VIP; VIPI); and 4) BRILLIANT Crios (CRI, Coltene) as indirect resin composite materials; 5) VITA Enamic (ENA, Vita) as a polymer-infiltrated ceramic network (PICN) material; 6) IPS e.max CAD (EMX, Ivoclar Vivadent), as a lithium disilicate ceramic material; 7) Ceramill ZI (CZI, Amann Girrbach), as a 3Y-TZP material; and 8) VITA Suprinity (SUP, Vita) and 7) Celtra Duo (CEL, Dentsply Sirona), as zirconia-reinforced lithium silicate ceramic materials. For each material, 6 blocks were used and processed as recommended by the respective manufacturer. For each indirect material, an MDP-containing silane (Monobond N, Ivoclar Vivadent) followed by an MDP-free universal adhesive system (Peak Universal Bond/Ultradent) were applied as per the manufacturers’ instructions specific for each material. Cylinder-shaped transparent matrices were then filled with resin cement (NX3; Kerr) and light cured. Specimens were stored in water (37°C/24 h) and tested in shear (1.0 mm/min). Mean µSBS were statistically analyzed using 1-way ANOVA (α = 0.05) and Tukey post-hoc test.
Results: ENA (25.5 ± 2.8) resulted in statistically higher mean µSBS compared with LAV (18.9 ± 3.0), BRV (16.3 ± 1.1), and VIP (11.9 ± 2.6) (p < 0.001). ENA showed similar mean µSBS compared with EMX (23.2 ±3.1), CZI (23.7 ± 2.4), SUP (23.6 ± 2.2), CRI (22.3 ± 2.2), and CEL (20.8 ± 1.9) (p > 0.05).
Conclusions: ENA resulted in the highest mean µSBS. No significant differences were observed when all indirect resin composite materials were compared. The zirconia/lithium disilicate hybrid materials (SUP and CEL) showed similar mean bond strength compared with CZI and EMX.