Elastic moduli of resin-composites with silorane, ormocer and dimethacrylate matrices

Objective: To determine the elastic properties of a silorane- and an experimental ormocer- versus dimethacrylate-based matrix composites. Methods: Two materials of novel matrix chemistry: Filtek Silorane (SIL) and experimental Ormocer (ORM) were compared with two dimethacrylate composites: Grandio (GRA) and ELS - Ceramco (ELS). Cylindrical specimens (5 mm diameter x 6 mm) were prepared in moulds from each material (n=12) by thorough irradiation and stored dry for 24 h. Six specimens were used to measure the Young's modulus (E), allowing free radial expansion under axial-compressive loading at 1mm/min. The other six specimens were radially constricted in a rigid stainless steel ring during compression, from which the bulk modulus (B) was calculated using equations of elasticity. Poisson's ratio (ν) was calculated from the equation ν = 0.5 - (E/6B). The results were submitted to One-way ANOVA (p=0.05). To determine any correlation between elastic moduli and w/w filler content, Pearson's test was applied. Results: The filler content, E, B and ν values are reported in the Table below. Statistically significant differences were found among the materials. A significant correlation was observed between elastic moduli and filler content (r²=0.99). Thus materials with higher filler content, i.e: ORM and GRA, presented higher elastic moduli than SIL and ELS.