With over 30% whitening agent, the Smilepen Mouthwash Serum is the most powerful teeth whitening serum for a brighter smile ✨. It protects your tooth structure while simultaneously whitening your teeth as part of your daily oral care routine. In areas where toothbrushes and traditional whitening products struggle to reach, the Smilepen Mouthwash Serum is the perfect addition for all-around white teeth. The added hyaluronic acid also nourishes and revitalizes your gums while supporting a healthy oral flora.