Sucking a thumb or a pacifier usually does not result in long-term harm to a young child’s teeth, or the “bite” that occurs when lower and upper teeth are pressed together, so long as she stops by the time the permanent teeth come in, usually around age 6..

“But sucking a pacifier may have already caused some effect on her bite, depending on the length of time she uses the pacifier and how intensely she sucks,” said pediatric dentist, Dr. Man Wai Ng, Dentist-in-Chief at Children’s Hospital in Boston. Intense sucking can cause narrowing of the palate and affect the growth of the jaws.

In general, pacifiers “are very useful to children,” said Dr. Barbara Howard, assistant professor of pediatrics at Johns Hopkins University. “It provides physiological stabilization. It’s been shown to make digestion better, to calm a child down and to help get more oxygen into the system.”

But pacifier use is also associated with more ear infections because it creates a vacuum in the ear, which can suck fluid out of the bloodstream into the middle ear. Because pacifiers often fall on the ground, they may also be full of bacteria and viruses. Kids who fall asleep with a pacifier are also more likely to wake up during the night. Even if they put the pacifier back in themselves, their sleep has still been disrupted, said Howard.

In some cases, parents who can’t get a child to stop using a pacifier “aren’t very good at setting limits in general,” said Howard. These parents “can’t tolerate children being in any distress. But part of childhood is to get immunized against increasing stress while you are under the protection of your loving caregivers,” Howard said. One tactic is to have a ceremony to bury the pacifier in the garden, then focus the child’s attention on getting a “grown-up” toy. Or just throw the pacifier away.