Properties of Experimental Composites: Influence of Fillers and Post-Polymerization Methods

Objectives: The aim of the study was to evaluate the influence of different inorganic fillers content and post-polymerization methods on flexural strength (FS) and elastic modulus (EM) of experimental resin-based composites.
Methods: Experimental resin-based composites were prepared with 30 wt.% of organic matrix and 70 wt.% of filler constituted by C1-100%, C2-90%, C3-80% and C4-70% of silanated barium-glass fillers. Silicon matrices (7x2x1mm) were fulfilled with experimental composites and photocured by Bluephase-G2 (energy dose-36J). After, specimens were subdivided in post-polymerization protocols (n=10): P0-without post-polymerization; P1- Beta Visio unit 470mW/cm² for 15 min; P2- 5 min in a microwave at 500W. Specimens were stored in deionized water at 37°C for 24h. FS and EM were measured in three-point bending test at 0.5mm/min until fracture by universal test machine (Instron). Data were submitted to Shapiro-Wilk, two-way ANOVA and Tukey tests (α=5%).
Results: Interaction was observed between experimental composites and post-polymerization (p<0.01) for FS. C4/P2 (112.88±22.30) showed higher FS values with significant difference from C4/P1 (85.25±19.29). The lowest FS value was observed for C1/P0 (80.09±22.56) significantly different from C1/P1 (104.83±15.48), C1/P2 (101.31±17.90) and C4/P0 (111.63±19.39). For EM no interaction was observed between factors in study (p>0.05), but experimental composites and post-polymerization indicated significant difference (p<0.05; p<0.01, respectively). C4 (2.42±0.48) showed higher EM values, significantly different from C1 (2.13±0.61). The highest EM values was observed for P2 (2.86±0.46) with significant difference from P0 (1.95±0.38) and P1 (2.07±0.27).
Conclusions: It could be concluded that post-polymerization methods improve the properties of experimental composites. In addition, the content of inorganic fillers and post-polymerization methods influenced the FS and EM of experimental resin-based composites showing that lower inorganic fillers higher the ME and FS.