Evaluation of Microshear Bond Strength of Four Different CAD-CAM Polymer-Infiltrated Ceramic Materials after Thermocycling

Purpose To evaluate the bond strength of three monolithic hybrid ceramics/resin nanoceramics and a zirconia-reinforced lithium silicate to resin cement after thermocycling. Materials and Methods Using four materials, including Vita Enamic (VITA Zahnfabrik), Lava Ultimate (3M ESPE), Crystal Ultra (Digital Dental), and Vita Suprinity (VITA Zahnfabrik), 64 specimens were prepared with dimensions of 4 mm x 3 mm x 1.5 mm. Vita Suprinity samples were sintered at 840 degrees C for 8 min. After polishing and cleaning all the samples in each group (n = 16), they were subjected to their recommended surface treatment: 10% hydrofluoric acid for Vita Enamic (60s) and Vita Suprinity (20s); air abrasion of Lava Ultimate and Crystal Ultra with 50 u Al2O3 particles. Then, tygon tubes were filled with dual cure resin cement (Panavia F2.0), cured and then subjected to thermal cycling (2000 cycles; 5-55 degrees C). The microshear bond strength was measured using microtensile testing machine. The data were analyzed using Welch and Games-Howell tests (alpha = 0.05). The mode of failure was also evaluated using a stereomicroscope. Results The highest and the lowest mean microshear bond strength belonged to the Crystal Ultra (7.71 +/- 1.54 MPa) and Vita Suprinity (4.73 +/- 1.87 MPa) groups, respectively. The differences between groups were significant and Crystal Ultra had higher bond strength in comparison to all three materials (p < 0.05). Conclusion Hybrid ceramics showed higher bond strength to resin cements in comparison to resin nanoceramics and zirconia-reinforced lithium silicate materials.