In this work nanocomposites were prepared using a mixture of Bis-phenol A glycidyl methacrylate and triethylene glycol dimethacrylate (Bis-GMA/TEGDMA, 70/30 w/w, Resin) and sodium montmorillonite (MMT) as inorganic filler in concentrations of 0.1, 0.2, 0.3 and 0.4 phr. Two groups were prepared: the first one by adding hydrated MMT to the resin (Resin-MMTh) and the second one by adding clay slurry to the resin (Resin-MMTs). The properties of these two groups were compared with the control group (Bis-GMA/TEGDMA without clay). The mechanical properties (flexural strength and flexural modulus) have been evaluated according to the established standards for dental materials application; the conversion degree of nanocomposites based on Bis-GMA/TEGDMA by FTIR; the state which the clay sheets are found in the polymer matrix has been studied by using XRD; the morphology of the nanocomposite has been analyzed with SEM and finally the interaction of the clay sheets with the polymeric matrix through rheological tests. For both groups (Resin-Na+Mth and Resin-Na+Mts) at a concentration of 0.3 phr and 0.2 phr, in the flexural strength tests, there were increases of 34% and 41% respectively, without significant variation in the flexural modulus. The values obtained for the conversion degree were higher with respect to the control at all concentrations and both groups except at a concentration of 0.4 phr for Resin-MMTh, this fact showed that there was no interference of the clay particles in the polymerization process. For a concentration of 0.3 phr for the two groups the results obtained by XRD showed that Bis-GMA/TEGDMA is able to penetrate the interlaminar space of the MMT causing a polymer intercalation in the clay sheets. Scanning electron microscopy exhibited a rough surface for the two groups containing 0.3 phr of clay, indicative of an electrostatic interaction between the nanoparticle and the polymer. Similarly, rheological tests also showed that there is an interaction betw