Contraction stress, elastic modulus, and degree of conversion of three flowable composites

Cadenaro M, Codan B, Navarra CO, Marchesi G, Turco G, Di Lenarda R, Breschi L. Contraction stress, elastic modulus, and degree of conversion of three flowable composites. Eur J Oral Sci 2011; 119: 241–245. © 2011 Eur J Oral Sci The aim of this study was to measure the contraction stress of three flowable resin composites and to correlate the stress with the elastic modulus and the degree of conversion. One low‐shrinkage (Venus Diamond Flow) and two conventional (Tetric EvoFlow and X‐Flow) flowable composites were polymerized for 40 s with a light‐emitting diode (LED) curing unit. Contraction force was continuously recorded for 300 s using a stress‐analyser, and stress values were calculated at 40 s and at 300 s. The maximum stress rate was also calculated for each specimen. The elastic modulus of each composite was assayed using a biaxial flexural test, and degree of conversion was analysed with Raman spectroscopy. X‐Flow exhibited higher stress values than the other tested materials. Venus Diamond Flow showed the lowest stress values at 40 s and at 300 s, and the lowest maximum stress rate. Stress values were correlated with elastic modulus but not with degree of conversion, which was comparable among all tested materials.