Lea S. Prott

Objective To investigate the effect of ceramic thickness and dental substrate (enamel vs. dentin/enamel) on the survival rate and failure load of non‐retentive occlusal veneers. Materials and Methods Human maxillary molars ( n = 60) were divided into five test‐groups ( n = 12). The groups (named DE‐1.5, DE‐1.0, DE‐0.5, E‐1.0, E‐0.5) differed in their dental substrate (E = enamel, DE = dentin/enamel) and restoration thickness (standard: 1.5 mm, thin: 1.0 mm, ultrathin: 0.5 mm). All teeth were prepared for non‐retentive monolithic lithium‐disilicate occlusal veneers (IPS e.max Press, Ivoclar). Restorations were adhesively cemented (Syntac Classic/Variolink II, Ivoclar) and exposed to thermomechanical fatigue (1.2 million cycles, 1.6 Hz, 49 N/ 5–55°C). Single load to failure was performed using a universal testing‐machine. A linear‐regression model was applied, pairwise comparisons used the Student–Newman–Keuls method ( p < 0.05). Results Three dentin‐based occlusal veneers (one DE‐1.0, two DE‐0.5) revealed cracks after fatigue exposure, which corresponds to an overall‐survival rate of 95%. Load to failure resulted in the following ranking: 2142 N(DE‐0.5) > 2105 N(E‐1.0) > 2075 N(E‐0.5) > 1440 N(DE‐1.5) > 1430 N(DE‐1.0). Thin (E‐1.0) and ultrathin enamel‐based occlusal veneers (E‐0.5) revealed high failure loads and surpassed the standard thickness dentin‐based veneers (DE‐1.5) significantly ( p = 0.044, p = 0.022). Conclusion All tested monolithic lithium disilicate occlusal veneers obtained failure loads above physiological chewing forces. Thin and ultrathin enamel‐based occlusal veneers outperformed the standard thick dentin‐based occlusal veneers. Clinical Significance Minimally invasive enamel‐based occlusal veneer restorations with non‐retentive preparation design may serve as a conservative treatment option.