The assumption is that the IPN have antibacterial activity against S.mutans. Today, there is no dental material that can solve the problem of caries development in margins of provisional restorations. Many people stay with the provisional restoration for a long period in the oral cavity, in which the risk for caries development rises. Therefore there was a need to test the in vivo activity of the nanoparticles in provisional cement, on S.mutans in the margins of provisional restorations.