When a child continues thumb sucking into their school-age years, long-term problems can occur. Thumb sucking (or using a pacifier) changes the way that a child’s teeth grow. The pressure from the thumb pushes the teeth to stick out. This affects a child’s entire mouth because the teeth no longer meet properly when the child bites down. This is known as a crossbite.
When the upper and lower teeth stick out as they grow, other problems like broken teeth can occur. Children who suck their thumbs after toddlerhood are more likely to need orthodontic treatments such as braces, expanders, and other tools to correct the shape of the teeth.