In Vitro Mastication Simulation and Wear Test of Virgilite and Advanced Lithium Disilicate Ceramics

To compare wear behavior, durability during in vitro mastication simulation, and fracture force of an established and a novel lithium disilicate CAD/CAM material, as well as to examine the impact of cementation and reduced ceramic thickness on durability and fracture force.

Specimens (n = 8 per group) were prepared from lithium disilicate (LS₂; IPS e.max, Ivoclar Vivadent) and advanced lithium disilicate (ALD; Cerec Tessera, Dentsply Sirona). Specimens were polished, and two-body wear test and thermocycling were performed (50 N, 120,000 cycles, 1.6 Hz, H₂O dist., 5°C/55°C, 600 cycles). Maximum vertical loss, surface roughness, surface roughness depth, and antagonist wear were determined. Single crowns (n = 8 per group; thickness 1.5 mm/1.0 mm) were manufactured from LS₂ and ALD and mounted on human molar teeth with adhesive resin (AB; CalibraCeram, Dentsply Sirona), glass-ionomer cement (GIC; Ketac Cem, 3M ESPE), and hybrid glass-ionomer cement (HGIC; Calibra Bio, Dentsply Sirona). Thermocycling and mechanical loading (2 × 3000 × 5°C/55°C, 2 minutes, H₂0 dist., 1.2 × 10⁶ 50 N) were performed. Fracture force was determined by a universal testing machine (1446, ZwickRoell), and one-way analysis and Bonferroni post hoc test (α = .05) were used for statistical analyses.

Mean (ALD: 210 ± 42.4 μm; LS₂: 264.3 ± 56.1 μm) and maximum (ALD: 391.1 ± 86.3 μm; LS₂: 518.3 ± 113.2 μm) wear between groups were significantly different (P ≤ .047). Fracture force varied between 1,911.4 ± 468.4 N (ALD/AB 1 mm) and 2,995.3 ± 880.6 N (LS₂/GIC), without significant differences (P ≥ .152).

ALD showed better wear behavior than LS₂, but provided similar fracture force. Cementation and reduction of ceramic thickness had only minor effects on fracture force.