Is it true that eating a lot of sugar will rot your teeth from the inside out, even if u frequently brush.?? :-)

Cavity: Cavities go from outside in, not from inside out. Sugar is converted by the bacteria that live in your mouth into acid, and the acid etches calcium out of the surface of your enamel, allowing other bacteria to penetrate from the outside into the tooth itself. In other words, a cavity is an infection. See your Dentist for professional care at least 2x/year, keep teeth clean, cut down on sweets.