What is a good way to strengthen my teeth from within?

Too late: Your adult teeth were forming when you were a child, and the internal make-up is primarily genetic. You should be more concerned with taking care of the outside (enamel) by eating well, brushing & flossing properly, and visiting your dentist every six months.

Can't: But you can help your children. As teeth form over many years before they erupt into the mouth, very small amounts of Fluoride can strengthen the forming enamel, such as fl in the water supply or fl supplements. Once the tooth erupts the outer layer of the tooth can be strengthened with topical fl and fl containing toothpastes or mouth washes. See your dentist for advice tailored to your area.