Sippy cups are useful when transitioning to an open cup thanks to the similar sucking motion babies use with a bottle. However, using sippy cups for an extended period of time can lead to developmental problems, like tooth decay or speech problems.  Despite their convenience, straw sippy cups are often used for too long and sometimes with liquids high in sugars, like juice or soda. These sugars can stay on your child’s teeth, leading to plaque and other dental issues, such as cavities.