The influence of aging on the fracture load of milled monolithic crowns

BACKGROUND: This in-vitro study was conducted to assess the effect of aging on the fracture load of molar crowns fabricated with monolithic CAD/CAM materials. METHODS: The crown restorations were produced from Cerasmart, Vita Enamic, and IPS e.max CAD blocks. Aging was applied to the 10 samples each of monolithic CAD/CAM materials (n = 10). Dual-axis chewing simulator (50 N, 1.1 Hz, lateral movement: 1 mm, mouth opening: 2 mm, 1,200,000 cycles) and thermocycling (± 5–55 °C, 6000 cycles) were applied as an aging procedure. 10 samples each of monolithic CAD/CAM materials without aging (n = 10) were considered the control group. 6 tested groups were obtained. Then, all samples were evaluated in a universal testing machine to determine the fracture loading values’. RESULTS: There was not a statistically significant difference between the fracture load values before and after aging for all samples of Cerasmart, Vita Enamic, and IPS e.max CAD (p > 0.005). In a comparison of the monolithic materials together, a statistically significant difference was found between the fracture load values of IPS e.max CAD and Vita Enamic crowns before aging (p = 0.02). Also, Vita Enamic crowns (1978,71 ± 364,05 N) were found different from the IPS e.max CAD (p = 0.005) and Cerasmart crowns (p = 0.041) after aging. CONCLUSIONS: Dynamic aging with 1.200.000 cycles was found to have no effect to fracture loading on milled Cerasmart, Vita Enamic, and IPS e.max CAD monolithic crowns.