Indentation hardness

Composite number

Tukey's range test

Statistics

Materials science

Dentistry

Post hoc

Mathematics

Vickers hardness test

Microstructure

Fracture toughness

Composite material

Fiber

Medicine

Scanning electron microscope

Toughness

Dental Materials

To investigate the surface micro-hardness (VHN) and fracture toughness (KIC) of resin-composites, with and without incorporated short fibers, after solvent storage. Three resin-composites incorporating fibers, additional to particle reinforcement, were examined: everX™, NovoPro Fill™ and NovoPro Flow™. Four composites were used as controls, with only particle reinforcement: Filtek bulk Fill™, Filtek bulk one™, Filtek XTE™, and Filtek Flow XTE™. For hardness measurement, materials were cured in 2 mm thick molds for 20 s by a LED source of average irradiance 1.2 W/cm2. Specimens (n = 6/group) were stored dry for 1 h and then in either water or 75% ethanol/water for 1 h, 1 day and 30 days at 37 ± 1 °C. Vickers hardness was measured under a load of 300 g for 15 s. For fracture toughness (KIC) measurements, single-edge-notched specimens (n = 6/group) were prepared: (32 × 6 × 3 mm) for 3-point bending and stored for 1 and 7 days in water at 37 °C. Fractured surfaces of fiber-reinforced composite were examined by scanning electron microscopy (SEM). VHN data were analyzed using three-way ANOVA, one-way ANOVA and the Tukey post hoc test (p ≤ 0.05). KIC data were analyzed by two-way ANOVA and one-way ANOVA and the Tukey post hoc test (p ≤ 0.05). An independent t-test was used to detect differences (α = 0.05) in KIC between stored groups for each material. VHN decreased for all composites with storage time in both solvents, but more appreciably in 75% ethanol/water (an average of 20%). KIC ranged from 2.14 (everX Posterior) to 0.96 NovoPro Flow) MPa. m0.5. The longer storage period (7 days) had no significant effect on this property relative to 1 day storage. Reinforcement with short fibers, and possibly matrix compositional differences, significantly enhanced the fracture toughness of EVX. However, for nano-fiber containing composites, there were no evident beneficial effects upon either their fracture toughness or hardness compared to a range of control composites. Water storage for 7 days of all these resin-composites produced no significant change in their KIC values, relative to 1 day storage.

Hardness and fracture toughness of resin-composite materials with and without fibers