Previous studies demonstrated that a cranberry high-molecular-mass, nondialyzable material (NDM) can inhibit adhesion of numerous species of bacteria and prevents bacterial coaggregation of bacterial pairs. Bacterial coaggregation leads to plaque formation leading to biofilm development on surfaces of oral cavity. In the present study, we evaluated the effect of low concentrations of NDM on Streptococcus gordonii metabolic activity and biofilm formation on restorative dental surfaces. We found that the NDM selectively inhibited metabolic activity of S. gordonii, without affecting bacterial viability. Inhibiting the metabolic activity of bacteria in biofilm may benefit the health of the oral cavity.