Dr i think my 2 year babys upper jaw teeth starting to cavity. its look like a black colour in his upper jaw line. how to prevent this?

A. Start brushing your child's teeth as soon as the first one appears. ... For children younger than 3 years old, use only a small amount of toothpaste, about the size of a grain of rice. ... Floss your child's teeth daily after age 2. Make sure your child eats a well-balanced diet.