Always have a soda on hand? Carbonated drinks can be bad for your teeth, because they tend to be full of sugar and are very acidic. Even diet sodas are harmful due to the high acid levels which are corroding to your enamel. The effects of soda on teeth are even worse if you slowly sip it over a long period of time. The acidity in soda can lead to dental health problems such as decay around your gum line and decalcification of the enamel.