What Is Chronic Mouth Breathing?
Normal breathing occurs through the nose. The nose warms, filters, and humidifies air before it reaches the lungs. It also produces nitric oxide, a gas that helps regulate blood flow and oxygen exchange. When a child cannot breathe easily through the nose, they compensate by breathing through the mouth.
Occasional mouth breathing during a cold or vigorous exercise is normal. Chronic mouth breathing means the child relies on mouth breathing as their primary breathing pattern, even at rest, during sleep, or during quiet activities. Over time, this altered breathing pattern changes the resting position of the tongue, lips, and jaw, which can reshape the growing face and dental arches.
How Mouth Breathing Affects Facial Growth
When a child breathes through the nose, the tongue rests against the roof of the mouth (palate). This gentle, constant pressure helps the upper jaw grow wider and forward. When a child breathes through the mouth, the tongue drops to the floor of the mouth. Without that upward pressure, the upper jaw tends to grow narrow and the face tends to grow longer (vertically) rather than forward.
This pattern is sometimes called long face syndrome or adenoid facies. Over years of mouth breathing, the changes in bone growth can become significant enough to affect bite alignment, airway space, and facial appearance.
Causes of Mouth Breathing in Children
Children breathe through their mouths because something is blocking or limiting airflow through the nose. Identifying and treating the underlying cause is the first step in resolving the problem.
Enlarged Adenoids and Tonsils
Enlarged adenoids are the single most common cause of mouth breathing in children. Adenoids are lymphoid tissue located at the back of the nasal passage. When they are enlarged, they physically block airflow through the nose. Enlarged tonsils can also contribute to airway obstruction, especially during sleep. Adenoid and tonsil enlargement is most common between ages 3 and 7, when the lymphoid tissue is naturally at its largest.
Allergies and Chronic Nasal Congestion
Allergic rhinitis (hay fever) causes swelling of the nasal tissues, excess mucus production, and nasal congestion. Children with year-round allergies to dust mites, pet dander, or mold may have chronic nasal obstruction that forces mouth breathing. Seasonal allergies can also contribute during peak allergy months.
Structural Causes
A deviated nasal septum (the wall between the two nasal passages is off-center) can restrict airflow through one or both nostrils. Nasal polyps, turbinate hypertrophy (swollen structures inside the nose), or a narrow nasal passage can also contribute to chronic nasal obstruction.
Habitual Mouth Breathing
Some children continue to breathe through their mouths even after the original obstruction (such as enlarged adenoids) has been treated. This happens because the muscles of the face, lips, and tongue have adapted to the mouth-breathing pattern. In these cases, myofunctional therapy (exercises to retrain oral and facial muscles) may be needed alongside any dental or orthodontic treatment.
Signs and Diagnosis
Mouth breathing is not always obvious. Some children mouth-breathe primarily during sleep, making it harder for parents to detect. Knowing the signs can help you identify the problem early.
Signs Your Child May Be a Mouth Breather
Watch for these signs at home and discuss them with your child's dentist or pediatrician.
- Lips are open at rest (during the day or during sleep)
- Snoring, noisy breathing, or sleep-disordered breathing
- Dry, cracked lips or frequent dry mouth
- Dark circles under the eyes (sometimes called allergic shiners)
- Waking up tired, morning headaches, or daytime fatigue
- Difficulty concentrating at school or behavioral issues (which can mimic ADHD symptoms)
- Crowded or crooked teeth
- A narrow, high-arched palate (roof of the mouth)
- An elongated face, recessed chin, or open mouth posture
- Frequent cavities or gum inflammation despite good brushing
Dental and Orthodontic Effects
Chronic mouth breathing can cause or contribute to several dental problems.
- Narrow upper jaw (maxilla): Without the tongue's upward pressure, the palate stays narrow, leading to a crossbite or crowded upper teeth
- Open bite: The front teeth may not fully overlap, leaving a gap between the upper and lower teeth when the mouth is closed
- Increased overjet: Upper front teeth may protrude forward
- Dry mouth: Reduced saliva flow increases the risk of cavities, gum disease, and bad breath
- Gummy smile: Excess vertical growth of the upper jaw can cause more gum tissue to show when smiling
- Malocclusion (misaligned bite) requiring orthodontic treatment
How Mouth Breathing Is Diagnosed
A pediatric dentist or orthodontist may be the first to notice signs of mouth breathing during a routine dental exam. They will look at the palate shape, tooth alignment, facial profile, and gum health. They may refer your child to an ENT specialist (otolaryngologist) for evaluation of the nasal airway, adenoids, and tonsils.
The ENT may perform a nasal endoscopy (a thin flexible camera inserted through the nose) to visualize the adenoids and nasal passages. Allergy testing may also be recommended if allergic rhinitis is suspected. In some cases, a sleep study may be ordered to evaluate for obstructive sleep apnea.
Treatment Options
Treatment for mouth breathing in children addresses both the cause of the nasal obstruction and any dental or skeletal changes that have already occurred. A team approach involving a pediatric dentist, orthodontist, ENT, and sometimes a myofunctional therapist often produces the best results.
Treating the Underlying Cause
If enlarged adenoids or tonsils are the primary obstruction, an adenoidectomy (surgical removal of the adenoids) or adenotonsillectomy (removal of both adenoids and tonsils) may be recommended. These are common pediatric procedures with well-established safety profiles. If allergies are the cause, treatment with nasal corticosteroid sprays, antihistamines, or allergen avoidance strategies can reduce nasal swelling and restore nasal breathing.
Resolving the nasal obstruction is the most critical first step. Without a clear nasal airway, other treatments (orthodontic or behavioral) are less likely to succeed long-term.
Orthodontic Intervention
If mouth breathing has already caused a narrow upper jaw, a palatal expander is one of the most effective treatments. This device is cemented to the upper back teeth and gradually widens the palate over several weeks. Expanding the palate not only creates more room for the teeth but also widens the floor of the nasal passage, which can improve nasal airflow.
Palatal expansion works best during the early growth years, typically between ages 5 and 10, before the midpalatal suture (the growth seam in the roof of the mouth) begins to fuse. In older teens and adults, surgical assistance may be needed to achieve expansion. Other orthodontic treatments, such as braces or aligners, may be recommended later to correct tooth alignment once the jaw has been expanded.
Myofunctional Therapy
Myofunctional therapy involves exercises that retrain the muscles of the tongue, lips, and face to support proper nasal breathing, tongue posture, and swallowing patterns. A trained myofunctional therapist guides the child through a series of exercises practiced daily at home.
This therapy is particularly important for children who continue to mouth-breathe out of habit after the nasal obstruction has been treated. It helps establish the correct resting tongue position (against the palate), lip seal at rest, and nasal breathing as the default pattern.
Treatment Costs
Because mouth breathing treatment often involves multiple providers and types of treatment, costs can vary significantly. Costs vary by location and provider.
Typical Cost Ranges
An ENT evaluation and nasal endoscopy typically costs $150 to $400. Adenoidectomy or adenotonsillectomy ranges from $2,000 to $5,000 (including facility and anesthesia fees). A palatal expander typically costs $1,000 to $3,000, which may be part of a larger orthodontic treatment plan. Myofunctional therapy sessions range from $75 to $200 per session, with most programs lasting 3 to 6 months. Allergy testing and treatment costs vary widely depending on the approach.
Insurance Coverage
Medical insurance typically covers ENT evaluations, allergy testing, and adenoidectomy/tonsillectomy when medically necessary. Dental insurance may cover orthodontic treatment including palatal expanders, depending on the plan and the child's age. Many plans have orthodontic maximums (often $1,000 to $2,000 lifetime). Myofunctional therapy coverage varies and is not included in most standard plans. Check with both your medical and dental insurance providers for specific coverage details.
When to Seek Help
If you notice that your child breathes through their mouth most of the time, snores regularly, or has any of the dental or facial changes described above, bring it up at your child's next dental or pediatric appointment. The earlier mouth breathing is identified and treated, the better the outcomes for facial and dental development.
Do not wait for all symptoms to appear. Even subtle signs like lips that are always slightly parted or frequent dry mouth are worth mentioning to your child's dentist.
Signs That Need Prompt Attention
Certain signs suggest the mouth breathing may be affecting your child's health more seriously and should be evaluated soon.
- Loud snoring with pauses in breathing (possible obstructive sleep apnea)
- Bedwetting in a child who was previously dry at night
- Significant daytime sleepiness or difficulty concentrating at school
- Failure to thrive or poor growth
- Restless sleep, frequent waking, or sleeping in unusual positions (such as with the neck hyperextended)
Find a Specialist for Mouth Breathing
A pediatric dentist is often the first provider to identify the dental effects of mouth breathing during routine exams. They can assess your child's palate shape, bite, and oral habits and coordinate referrals to other specialists as needed.
Depending on the cause and effects, your child may benefit from seeing an orthodontist (for palatal expansion and tooth alignment), an ENT specialist (for adenoid/tonsil evaluation and nasal obstruction), an allergist (for allergy management), or a myofunctional therapist. You can search for a pediatric dentist or orthodontist in your area using our provider directory.
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