Hardness and fracture toughness of resin-composite materials with and without fibers. Issue 8 (August 2019)

• Record Type: Journal Article
• Authors: Alshabib, Abdulrahman; Silikas, Nick; Watts, David C.
• Is Part Of: Dental materials. Volume 35:Issue 8(2019)
• Page Start: 1194
• Page End: 1203
• Publication Date: 2019-08
• Subjects: Resin composites -- Fiber reinforcement -- Water storage -- Ethanol/water -- Fracture toughness -- Surface hardness; Dentistry -- Periodicals; Dental materials -- Periodicals; 617.695
• DOI: 10.1016/j.dental.2019.05.017
• Languages: English
• ISSNs: 0109-5641

Abstract

Abstract: Objective: To investigate the surface micro-hardness (VHN) and fracture toughness (KIC ) of resin-composites, with and without incorporated short fibers, after solvent storage. Methods: 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/cm 2 . 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. Results: 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. m 0.5 . The longer storage period (7 days) had no significant effect on this property relative to 1 day storage. Significance: 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.