Diametral tensile strength and Vickers hardness of a composite after storage in different solutions

This study evaluated the Vickers hardness (VHN) and diametral tensile strength (DTS) of the composite Z100 (3M ESPE) cured with: Quartz-Tungsten-Halogen light curing unit (QTH) (700mW/cm2- 40 s) and Argon laser (1,000mW/cm2- 10 s). Specimens of 2 mm depth and 8 mm diameter were immersed for 30 days at 37 degrees C in different storage means: water, alcohol, acetic acid, propionic acid and dry (control). The DTS (n = 8) was determined with a crosshead speed of 0.5 mm/min. The VHN (n = 8) test was carried out using a 50 g load for 60 s. Statistical analysis was performed by two-way ANOVA and Tukey's test (alpha = 0.05). The relationship between VHN and DTS was observed by Pearson correlation. The light source was not significant in both tests (VHN: P < 0.18; DTS: P < 0.92), but the factor storage showed significance (P < .001). Mechanical properties of the control group were statistically superior to those of the other storage groups (VHN = 102.2; DTS = 42.3 MPa). The alcohol group showed the lowest VHN (93.3) and DTS (33.8 MPa) values, which were similar to values for propionic (VHN = 97.5; DTS = 35.9 MPa) and acetic acids (VHN = 97.8; DTS = 36.1 MPa), but different from that of water (VHN = 102.2; DTS = 42.3 MPa). The relationship between VHN and DTS values presented a positive correlation (r2 = 0.90; P < 0.01).