Purpose: The aim of this study was to assess the water sorption and determi
ne the influence of water on flexural properties of a composite resin cemen
t of 2 different viscosities. Materials and Methods: A dual-cured composite
resin cement of 2 different viscosities was tested according to Internatio
nal Standards Organization standards for dental composite materials. The sa
mples tested for water sorption were stored in distilled water for 7 or 60
days. The samples tested for flexural properties were divided into 2 groups
and stored either wet in distilled water or dry for 1, 7, or 60 days. Afte
r storage, a flexural test was performed with 3-point bending equipment. Re
sults: A significant increase in water sorption for both viscosities was re
gistered as the storage time increased, but no significant difference betwe
en the 2 viscosities was recorded. Significantly lower strength and modulus
were found for specimens that were wet stored for 60 days compared with th
e dry-stored ones, and significant changes in deflection at break were also
registered. There were no differences in flexural properties between the 2
viscosities. Because of the lubricant and plasticizing effect of water on
composite resin materials, the secant modulus and deflection at break seem
to be valid methods to describe the complete deflection behavior. Conclusio
n: Water has an important effect on the flexural properties of composite re
sin cement after 60 days of storage time. No significant differences in wat
er sorption and flexural properties were found between the high and low vis
cosities of the composite resin cement studied.