Dentists Dr. John Yoo and Dr. Jason Lin debunk 15 more myths about teeth. They explain how cavities can be reversed, if acidic foods will whiten teeth, and how long fillings last . They also talk about what you should do with a knocked-out tooth — as well as how long you have before it's gone for good. <br /><br />Yoo is a pediatric dentist in NYC and New Jersey and co-founder of Beam City Dental and Beam Street Dental.<br /><br />Linn is an orthodontist in NYC and New Jersey and co-founder of Beam City Dental and Beam Street Dental