Why we like it: Colgate Optic White Pro Series toothpaste is one whitening toothpaste that Dr. Fatima Khan, a dentist in Houston, Texas, recommends. Some of her reasons for recommending it include its trusted brand name and its 5% hydrogen peroxide whitening agent. Unlike other whitening agents that work by removing stains on the surface of the tooth, hydrogen peroxide can get inside the tooth so it whitens intrinsically as well as intrinsically. Sachar also recommends this toothpaste, saying, "Colgate Optic White Pro Series is the strongest professional-level whitening toothpaste on the market and would be my pick. Its 5% hydrogen peroxide content is the most effective bleaching agent in an OTC toothpaste, delivering visible results fast." However, she recommends patients use it with care and alternate it with a non-whitening or enamel-repairing toothpaste periodically. Who is it best for: Optic White Pro Series is best for anyone who is looking for a whitening toothpaste that contains both hydrogen peroxide and fluoride. Who should not get it: According to Khan, one downside to this toothpaste is that it contains sodium lauryl sulfate, or SLS, which may cause irritation, such as canker sores. Other popular whitening toothpastes may also contain SLS, so it's important to look at the ingredients before you buy a product if you're sensitive to it. "It may not be ideal for sensitive teeth or continuous long-term use without alternating with a non-whitening toothpaste," adds Sachar. "I recommend this one for short-term use or occasional whitening boosts. I tell my patients to use it for short periods of time and alternate it with a non-whitening or enamel-repairing toothpaste periodically."