Parents love them. Kids love them. But dentists detest them. What is it? The sippy cup. Studies now say kids who drink from sippy cups have a greater chance of tooth decay according to doctors. "Sippy cups are just an extension of the baby bottle habit," says pediatric dentist Dr. Cully Boren. The problem is with the lids. They have a valve control, only letting liquid out when a child sucks on it, but then the kids can keep the liquids in their mouths and on their teeth. That causes tooth decay according to Dr. Boren. "The bacteria in the mouth breaks the sugar down and it puts an acid in the mouth and it leaches the calcium out of the teeth and allows decay to enter the tooth." Dr. Boren says may parents rely on the sippy cup too much. " I see parents come in here all the time and the kids have multiple cavities in the mouth and they immediately take up the sippy cup after the child gets out of the chair." Dentist recommend that you only use sippy cups at meal times to prevent spills but when you are out and about it is probably best to use a real cup. "If you are drinking from a cup you are going to swallow the liquid in your mouth. A sippy cup you can go around it is like an extension of a nipple and they can sit there and suck on it. Some doctors also suggest that sippy cups can lead to additional health ailments like inner ear problems and speech impediments all caused by the constant sucking. So even though they are popular and a savior for sloppy spills, doctors agree your best bet is to limit the amount of time your child sips on a sippy cup.