Effect of short glass fiber/filler particle proportion on flexural and diametral tensile strength of a novel fiber-reinforced composite

Purpose: To evaluate the effect of glass fiber/filler particles proportion on flexural strength and diametral tensile strength of an experimental fiber-reinforced composite. Methods: Four experimental groups (N = 10) were created using an experimental short fiber reinforced composite, having as a factor under study the glass fiber (F) and filler particle (P) proportion: F22.5/P55 with 22.5 wt% of fiber and 55 wt% of filler particles; F25/P52.5 with 25 wt% of fiber and 52.5 wt% of filler particles; F27.5/P50 with 27.5 wt% of fiber and 50 wt% of filler particles; F30/P47.5 with 30 wt% of fiber and 47.5 wt% of filler particles. The experimental composite was made up by a methacrylate-based resin (50% Bis-GMA and 50% TEGDMA). Specimens were prepared for Flexural Strength (FS) (25 mm x 2 mm x 2 mm) and for Diametral Tensile Strength (DTS) (3 x 6 0 mm) and tested at 0.5 mm/min in a universal testing machine. Results: The results (in MPa) showed significance (different superscript letters mean statistical significant difference) for FS (p < 0.009) and DTS (p < 0.001) - FS results: F22.5/P55: 217.24 +/- 20.64(B); F25/P52.5: 245.77 +/- 26.80(AB); F27.5/P50: 246.88 +/- 32.28(AB); F30/P47.5: 259.91 +/- 26.01(A). DTS results: F22.5/P55: 21.82 +/- 4A2(B); F25/P52.5: 22.00 +/- 7.40(B); F27.5/P50: 18.63 +/- 4.41(B); F30/P47.5: 31.05 +/- 2.97(A). In SEM analysis, areas without fiber reinforcement demonstrated to be more prone to the presence of bubbles and crack development. The group F30/P47.5 showed areas with a great quantity of fibers without empty spaces for crack propagation. Conclusion: Increasing fiber content results in higher flexural and diametral tensile strength of an experimental composite reinforced with glass fibers. (C) 2015 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.