Evaluation of a fibre reinforced composite properties for bulk filling

Objective: The potential for improved mechanical properties in a newly developed composite with fibres as the dispersed phase was evaluated. Methods: EverX Posterior™ - EXP - GC and other commercially available bulk fill composites (Filtek™ Bulk Fill- FBF - 3M, SonicFill ™- SF - Kerr, SureFil^® SDR^® - SDR - Dentsply, Venus^® Bulk Fill- VBF - Heraeus Kulzer and Xtra Base - XB - VOCO) were characterized. The dispersion of fibres on the EXP composite and the fracture surface of the samples were observed by Scanning Electron Microscopy. Composite samples lightcured with blue and violet wavelength LED device (G-Light, GC) were evaluated in terms of mechanical properties: flexural strength (ISO 4049), fracture toughness (ISO 20795-1) and Vickers hardness (0, 2 and 4mm in deep; 0 and 24hours). Data was statistically analysed. Results: SEM shows well dispersed fibres working as a reinforcing phase. ANOVA shows that the mechanical properties of the materials are statistically different among them. EXP, SF and XB were not statistically different in terms of flexural strength. Moreover, tested composite bars broke apart, in contrast to EXP samples, which remained attached. EXP calculated K_IC (2,55 ± 0,64) rests in the same order of the other composites studied, with EXP, FBF and VBF presenting no statistically significant differences. All the materials tested showed a decrease in hardness from the surface to the bulk and an increase of 10-50% between hardness values of recently cured and 24h aged samples. Conclusion: The addition of fibres to a methacrylate based matrix result in composites with either comparable or superior mechanical properties compared to the other bulk fill materials tested.