There are enough things for parents to worry about nowadays besides their infant sucking a thumb. I tell parents it is okay for infants and toddlers to soothe themselves by sucking a thumb. In fact, some ultrasounds show that babies suck on fingers in the womb during pregnancy, as it is a natural behavior. So sucking on a thumb for five minutes before going to sleep will not do harm. It is when excessive thumb-sucking occurs that problems may arise.

After permanent teeth have erupted, excessive sucking can change the growth pattern of the jaw and cause the front upper teeth to protrude.

You could say teeth are pretty dumb, because they don’t know who or what is pushing them—whether Invisalign clear aligner trays, braces or a thumb. If you push on a tooth, it will move. If you bite on something at an angle, such as a Popsicle stick, you will move the tooth. Pressure moves teeth, which is how braces and Invisalign work. Unfortunately, sucking on a thumb also causes pressure and can move teeth.

For those toddlers who do not naturally outgrow thumb-sucking (generally most stop on their own between ages two and four), orthodontists can help them break this habit.

In order to keep the thumb from going to a place where the kid can enjoy it, we can install an appliance called a fixed palatal crib to interrupt the pleasure of sucking on a thumb. It also often works for persistent tongue thrust (except those caused by airway issues and/neurologic issues).

This small metal appliance is attached to the upper teeth on the roof of the mouth as a mechanical restrainer or at least a reminder to stop sucking.

These appliances do work, but I tell parents that if they have a child who is not ready to stop sucking, you can create emotional problems. The key is to find ways to reward kids for not sucking their thumbs. Each child is different and should be treated as such.