Effect of glass fiber incorporation on flexural properties of experimental composites

Abstract

This study evaluated the effect of fiber addiction in flexural properties of 30 wt% silica filled BisGMA resin (FR) or unfilled Bis-GMA (UR). Ten groups were created (N = 10) varying the resin (FR or UR) and quantity of glass fibers (wt%: 0, 10, 15, 20, and 30). Samples (10 × 2 × 1 mm) were submitted to flexural strength test following SEM examination. Data were analyzed by two-way ANOVA, Tukey, and Student t-test (α = 0.05). Results for flexural strength (MPa) were FR-groups: 0% (442.7 ± 140.6)(C), 10% (772.8 ± 446.3)(ABC), 15% (854.7 ± 297.3)(AB), 20% (863.4 ± 418.0)(A), 30% (459.5 ± 140.5)(BC); UR-groups: 0% (187.7 ± 120.3)(B), 10% (795.4 ± 688.1)(B), 15% (1999.9 ± 1258.6)(A), 20% (1911.5 ± 596.8)(A), and 30% (2090.6 ± 656.7)(A), and for flexural modulus (GPa) FR-groups: 0% (2065.63 ± 882.15)(B), 10% (4479.06 ± 3019.82)(AB), 15% (5694.89 ± 2790.3)(A), 20% (6042.11 ± 3392.13)(A), and 30% (2495.67 ± 1345.86)(B); UR-groups: 0% (1090.08 ± 708.81)(C), 10% (7032.13 ± 7864.53)(BC), 15% (19331.57 ± 16759.12)(AB), 20% (15726.03 ± 8035.09)(AB), and 30% (29364.37 ± 13928.96)(A). Fiber addiction in BisGMA resin increases flexural properties, and the interaction between resin and fibers seems better in the absence of inorganic fillers increasing flexural properties.

Figure 1

Flexural strength (MPa) for all groups compared together. Green line refers to unfilled groups and blue line to filled groups. Different letters mean statistical significant differences with P < 0.05.

Figure 2

Flexural modulus (GPa) for all groups compared together. Green line refers to unfilled groups and blue line to filled groups. Different letters mean statistical significant differences with P < 0.05.

Figure 3

SEM images of groups. (a) SEM (original magnification: 150x) of UR-20 showing clear interaction between fibers and resin and homogeneous distribution of these components in the composite; (b) SEM of 20-FR (original magnification: 150x) showing interaction fibers and resin and heterogeneous distribution of these components in the composite; (c) SEM of 10-UR (original magnification: 1000x) showing the crack development region with a clear cohesive fracture around glass fibers within the crack (arrow); (d) SEM of 10-FR (original magnification: 1000x) showing the crack development region without resin cohesive fracture around glass fibers within the crack; (e) fiber dislodgement on 30-FR (original magnification: 150x) as a result of few resin matrix to keep fibers together.