Does artificial aging affect mechanical properties of CAD/CAM composite materials

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The purpose of this study was to determine the flexural strength and Weibull characteristics of different CAD/CAM materials after different in vitro aging conditions. The specimens were randomly assigned to one of the six in vitro aging conditions: (1) water storage (37 °C, 3 weeks), (2) boiling water (24 h), (3) hydrochloric acid exposure (pH: 1.2, 24 h), (4) autoclave treatment (134 °C, 200 kPa, 12 h), (5) thermal cycling (5000 times, 5–55 °C), (6) cyclic loading (100N, 50,000 cycles). No treatment was applied to the specimens in control group. Three-point bending test was used for the calculation of flexural strength . The reliability of the strength was assessed by Weibull distribution . Surface roughness and topography was examined by coherence scanning interferometry . Evaluated parameters were compared using the Kruskall–Wallis or Mann–Whitney U test. Water storage, autoclave treatment and thermal cycling significantly decreased the flexural strength of all materials (p < 0.05), whereas HCl exposure or cyclic loading did not affect the properties (p > 0.05). Weibull moduli of Cerasmart™ and Lava™ Ultimate were similar with control. Vita Enamic ® exhibited similar Weibull moduli in all aging groups except the HCl treated group (p > 0.05). R a values of Cerasmart™ and Lava™ Ultimate were in the range of 0.053–0.088 μm in the aged groups. However R a results of Vita Enamic ® were larger than 0.2 μm. Flexural strength of newly developed restorative CAD/CAM materials was significantly decreased by artificial aging . Cyclic loading or HCl exposure does not affect to the flexural strength and structural reliability of Cerasmart™ and Lava™ Ultimate.