As a lining or restoration material, flowable composites are popular due to their ease in use and agreeable marginal adaptation of tooth cavity. The purpose of the present study was to evaluate various properties of flowable composites which were claimed to be of high or low flowability by the manufacturers. For the study, twelve flowable composites from six different manufacturers were used. Based on the manufacturers' claim, they were divided into two groups: high or low flowability. The products grouped in high flowability showed significantly higher (p<0.05) flow rate (flow distance), polymerization shrinkage, and microhardness (on the top surface), regardless of light-curing unit, than those grouped in low flowability. On the other hand, water sorption and solubility showed nonsignificantly different values regardless of flowability. Through the study, flow rate had low correlation with microhardness (R<0.23), polymerization shrinkage (R<0.60), and water sorption and solubility (R<0.36) regardless of light-curing unit.

The DPSS laser of 473 nm achieved a similar level of polymerization within the specimens as those of the other LCUs even with much lower light intensity. This laser can be applied as a light source for light curing of composite resins.