Tooth decay in children younger than 3 years caused by sugar-containing liquids. The main cause of bottle dental decay is the practice of allowing a child to suck on a bottle of milk, formula, fruit juice, or other sweet drinks throughout the day or while in bed. These liquids cling to the teeth for hours, especially while the child is sleeping, since saliva flow and swallowing are reduced then. The bacteria in the mouth interact with the natural or refined sugars in the liquid, forming acids that can dissolve the tooth enamel and decay the teeth. Regular dental visits should be started by a child’s first birthday.