Shrinkage-strainShrinkage-stress Strain rate Modulus of elasticity Bulk-fill a b s t r a c tObjectives. To investigate a set of resin-composites and the effect of their composition on polymerization shrinkage strain and strain kinetics, shrinkage stress and the apparent elastic modulus.Methods. Eighteen commercially available resin-composites were investigated. Three specimens (n = 3) were made per material and light-cured with an LED unit (1200 mW/cm 2 ) for 20 s. The bonded-disk method was used to measure the shrinkage strain and Bioman shrinkage stress instrument was used to measure shrinkage stress. The shrinkage strain kinetics at 23 • C was monitored for 60 min. Maximum strain and stress was evaluated at 60 min. The shrinkage strain rate was calculated using numerical differentiation. Significance. The nature of the monomer system determines the amount of the bulk contraction that occurs during polymerization and the resultant stress. Higher values of shrinkage strain and stress were demonstrated by the investigated flowable materials. The bulk-fill materials showed comparable result when compared to the traditional resin-composites.

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