Evaluation of Linear Polymerization Shrinkage, Flexural Strength and Modulus of Elasticity of Dental Composites

Linear polymerization shrinkage (LPS), flexural strength (FS) and modulus of elasticity (ME) of 7 dental composites (Filtek Z350 (TM), Filtek Z250 (TM)/3M ESPE; Grandio (TM), Polofil Supra (TM)/VOCO; TPH Spectrum (TM), TPH3 (TM), Esthet-X (TM)/Denstply) were measured. For the measurement of LPS, composites were applied to a cylindrical metallic mold and polymerized (n = 8). The gap formed at the resin/mold interface was observed using scanning electron microscopy (1500x). For FS and ME, specimens were prepared according to the ISO 4049 specifications (n = 10). Statistical analysis of the data was performed with one-way ANOVA and the Tukey test. TPH Spectrum presented significantly higher LPS values (29.45 mu m). Grandio had significantly higher mean values for FS (141.07 MPa) and ME (13.91 GPa). The relationship between modulus of elasticity and polymerization shrinkage is the main challenge for maintenance of the adhesive interface, thus composites presenting high shrinkage values, associated with a high modulus of elasticity tend to disrupt the adhesive interface under polymerization.