Chewing with your mouth closed is just good manners…right?

This is the face of a mouthbreather

This is the face of a mouthbreather

Well, it IS good manners, because no one needs to see food being chewed, but chewing with the mouth open tells this dentist a LOT about dental and facial development. In fact, unless your child is playing sports or singing right now…the lips should always be closed!  Here comes the technical stuff…we call this “proper oral rest posture”, which means breathing through the nose, lips lightly closed, teeth slightly apart, tip of the tongue resting lightly just behind the front teeth on the palate.  Did you just check your own oral rest posture?

Why is proper oral rest posture important?

The lips and the tongue are made of muscle, and that muscle helps shape developing jaws, which makes enough room for all of the adult teeth to come in nice and straight. In fact, if your children are able to keep their lips closed most of the day from a young age, the chances are HUGE that they won’t need to visit the orthodontist! However, if you’ve ever BEEN to an orthodontist’s office, you will see that they are crazy busy, so most of these parents don’t know about the magic of proper oral rest posture.

I keep reminding my kids to chew with their mouths closed, but they forget.

While eating a meal this way becomes a bit of a habit, it’s possible your kids actully can’t breathe properly through their noses! This has become more common over the last few decades as allergies and asthma are on the rise.  Many times the culprit is enlarged tonsils and/or adenoids.  While these structures play an important role in helping your body deal with infection, often in early years when a developing child is exposed to many allergens (pet hair, dust, molds, dairy products as examples) these bits of tissue swell up enough to block your child’s ability to breathe properly through the nose. The end result? Open mouths…poor oral rest posture…crooked teeth.

I think my daughter can breathe through her nose, but she still chews with her mouth open!

Often this means that the jaw isn’t working properly.  For some animals, the jaw moves straight open and closed with no side-to-side motion.  However, humans chew sort of in a circle to be able to mash all the varied foods we eat. If the jaw joints aren’t working properly, this can lead to straight up-and-down chewing, which is inefficient.  Parents of children like this often say “my child takes forever to eat a meal!” and these kids get more food on their faces well beyond the age where it would be common (say, in teen years). The other thing that can happen is the food is poorly chewed and swallowed almost whole, and these children suffer needlessly from digestive problems.  It’s a big reason that some kids only eat softer foods…easier to chew, easier to swallow partly-chewed.

Will braces fix this?

Not necessarily. I’ll probably irritate some people by saying this…but many (not all) orthodontists are primarily concerned with straight teeth rather than jaw function.  After all, that’s what you as a parent asked for, right? In fact, the training most dentists and dental specialists received in dental school taught frighteningly little about proper jaw function, so we have to seek out these courses in post-graduate schools, and such courses can be hard to find.

So…what can I do to help my children?

First…test your child to see if s/he can breathe comfortably through the nose!  If not, a visit to the doctor and then an Ear Nose and Throat (ENT) specialist and/or allergist may be in order. Next…training in Myofunctional Therapy, which basically means training in the habit of proper oral rest posture. Finally…find a dentist (and possibly an orthodontist also) who has had training in treating these sorts of problems and get some help…the younger the child, the easier the fix!

Andrea Stevens is a cosmetic and family dentist in practice in Kanata, Ontario.  If you have dental questions, you can call her at 613-271-7091 or visit her at Please also feel free to leave comments or questions below, and Dr. Stevens will be happy to answer!