Aim: This study aimed to evaluate the effect of different preparation designs of advanced lithium disilicate (CEREC Tessera) occlusal veneer on marginal fit and fracture resistance.
Materials and methods: Twenty extracted mandibular molar teeth were used for occlusal veneers fabrication. Division of samples was carried out by the preparation design into two groups (n=10). group 1: The teeth were prepared with 900 shoulder finish line. group 2: The chamfer finish line was the technique of choice in teeth preparation. Both groups were subjected to thermocycling. The stereomicroscope was used to examine all samples for marginal fit before being subjected to the test of fracture resistance utilizing the universal testing machine.
Results: Marginal fit results showed that the shoulder finish line design had a significantly lower mean value (75.8±6.4 μm) than that using the chamfer finish line design mean value (128.1±12.6 μm). The fracture resistance results demonstrated that the shoulder design had a higher significant mean value (870.2±72.5 N) than that using the chamfer design (711.2±66.6 N).
Conclusions : Advanced lithium disilicate (CEREC Tessera) could be used in occlusal veneer restoration as their flexural strength and marginal fit values fall within the clinically accepted range. Regarding the preparation design, the shoulder design showed more resistance to fracture and better marginal fit than the chamfer finish line design after thermocycling.