Infants will tend to suck their thumb and while there are not teeth it will not hurt them to do so.  The real issue with thumb sucking comes from prolonged thumb-sucking.  Therefore it is in yours and your child best interest to do your best to discourage this thumb-sucking as your child gets older.

There are dental problems that may result from prolonged thumb-sucking in a child’s formative years. One of the large dental issues linked to prolonged thumb-sucking is tooth misalignment.  If a child sucks his or her thumb for a long time, it can cause baby teeth to come in crooked. This can lead to issues with their permanent teeth later in life and in some cases, it can even affect the jaw alignment, causing your child to develop and underbite, crossbite, or overbite.

However crooked teeth are not the only issue to prolong thumb-sucking. The roof of your child’s mouth may gradually become deformed if the sucking is frequent. This can lead to a number of issues later in life. The altered palate and crooked teeth may result in speech difficulties or impediments.