Mouth Breathing and Crooked Teeth: How Breathing Shapes Your Child's Bite

Short answer: Crowded teeth, open bite or crossbite? Long-term mouth breathing changes tongue and jaw position during growth.

Medically reviewed by Dr. Prashanth R. Reddy, ENT Surgeon (MS ENT) · Last reviewed: 31 October 2026

How breathing shapes the bite

During nasal breathing, the lips are closed and the tongue rests against the roof of the mouth. That steady, gentle pressure helps the upper jaw grow wide enough for the teeth. When a child breathes through the mouth, the tongue sits low, the lips part and the cheek muscles press inward. Over years of growth, the upper jaw can become narrow.

The result can be crowded teeth, a crossbite (upper teeth biting inside the lower), an open bite (front teeth not meeting) and protruding upper teeth. A 2021 systematic review found consistent differences in the jaws and faces of mouth-breathing children compared with nasal breathers (Zhao et al.).

Why it matters for braces

If the breathing problem isn't addressed, the forces that crowded the teeth are still there, and teeth can drift back after treatment.

Why do people breathe through the mouth?

Usually because the nose doesn't let enough air through. Common reasons are a deviated septum, swollen turbinates, nasal allergy, chronic sinusitis, nasal polyps and, in children, enlarged adenoids and tonsils. Sometimes it starts as a habit and stays even after the nose clears.

Signs you or your child may be a mouth breather

• Lips apart at rest or during sleep
• Snoring, dry mouth or drooling on the pillow
• Waking tired, dark circles under the eyes
• Bad breath and frequent throat clearing
• Always 'blocked' nose, especially at night

What helps

1. Find out why the nose is blocked. An ENT evaluation (examination plus a CT scan of the nose where needed) shows whether it's the septum, turbinates, allergy, sinuses or adenoids.
2. Treat the cause, from allergy control and nasal sprays to correcting a blockage when it's needed.
3. Work with your dentist or orthodontist on the teeth, gums and bite.
4. Re-train nasal breathing once the nose is open, with lips closed at rest.

When to see an ENT

If you or your child breathe through the mouth most of the time, snore, or have a constantly blocked nose, an ENT evaluation can find the cause.

References

• Zhao Z, et al. Effects of mouth breathing on facial skeletal development in children: a systematic review and meta-analysis. BMC Oral Health. 2021;21:108.
• Linder-Aronson S. Adenoids: their effect on mode of breathing and nasal airflow and their relationship to characteristics of the facial skeleton and the dentition. Acta Oto-Laryngologica Supplementum. 1970;265:1-132.

Related reading: Mouth breathing and bad breath · Mouth breathing and tooth decay · Mouth breathing and gum disease · Mouth breathing and a high-arched palate · Mouth breathing, a receding jaw and a long face

About the author

Dr. Prashanth R. Reddy is a Senior Consultant ENT Surgeon in Bengaluru (MS ENT; Fellowship in Rhinoplasty, Seoul; MBA, IIM Bangalore) with over two decades of practice. He sees patients at Sakra World Hospital, Marathahalli and at the ENTHealth360 clinic in Koramangala.

For educational purposes only. Not a substitute for medical advice. Please consult a qualified ENT specialist.