One of the main problems in dental medicine is the growth of bacterial biofilms on tooth surfaces which cause caries and periodontitis. We have developed a new system for oral hygiene and dental treatment that consists of either a paste or a rinsing solution containing calcium phosphate nanoparticles, functionalized with the antibacterial agent chlorhexidine. As calcium phosphate is the natural component of tooth mineral, it can lead to the remineralization of damaged enamel, while chlorhexidine prevents the colonization of the tooth surface by bacteria. In the form of a paste, a bifunctional system with both mineralizing and antibacterial properties is obtained. The nanoparticles may also stick to open dentin tubules at the root surface due to their coating with carboxymethyl cellulose. In vitro studies on teeth show that the paste sticks well to the root surface and closes dentin tubules.