What This Guide Covers
This guide explains how chronic mouth breathing affects a child's teeth, jaw, and facial growth. It covers causes, signs to watch for, and treatment options.
Most children breathe through their mouth now and then, especially during a cold. That is normal. The concern arises when mouth breathing becomes habitual, meaning a child breathes through the mouth most of the time, even at rest. Research shows that prolonged oral breathing during key growth years can change how the bones of the face and jaw develop. [1]
This guide is for parents who have noticed their child sleeping with an open mouth, snoring, or showing signs of crowded teeth. It is also useful if a dentist or pediatrician has already flagged mouth breathing as a concern. You will find specific information about causes, dental effects, the role of orthodontics, costs, and when to see a specialist.
The information here applies to children roughly between the ages of 3 and 12, the period when facial bones are growing most actively. Early recognition and treatment can make a meaningful difference in a child's dental and overall health.
How Mouth Breathing Affects a Child's Dental and Facial Growth
Habitual mouth breathing changes the resting position of the tongue, lips, and jaw, which over time can reshape growing facial bones.
Common Causes of Mouth Breathing in Children
The most frequent cause is nasal airway obstruction, a physical blockage that makes it hard to breathe through the nose. In children, this is most often caused by enlarged adenoids or tonsils. The adenoids are a patch of lymphoid tissue behind the nose. When they swell due to infection or chronic inflammation, they can block the nasal passage and force the child to breathe through the mouth. [1]
Allergic rhinitis (nasal allergies) is another leading cause. Swollen nasal tissues from dust, pollen, or pet dander restrict airflow. A deviated nasal septum, where the wall between the two nostrils is off-center, can also contribute. Some children have more than one factor at play. [5]
Less commonly, oral habits like prolonged thumb sucking or pacifier use can train the mouth to stay open and contribute to an open-mouth posture. [2] [4] Whatever the root cause, the result is the same: the child's mouth stays open for extended periods, and this changes how muscles and bones interact during growth.
Dental and Facial Effects
When a child breathes through the nose, the tongue naturally rests against the roof of the mouth (the palate). This gentle pressure helps the upper jaw widen as the child grows. When the mouth stays open, the tongue drops to the floor of the mouth. Without that upward pressure, the palate tends to grow narrow and high-arched. [1]
A narrow palate often leads to a posterior crossbite, a condition where the upper back teeth sit inside the lower back teeth instead of outside them. It also contributes to dental crowding because a narrower arch has less room for permanent teeth. [1] [3]
Research has identified a pattern often called "long face syndrome" or adenoid facies. Children with this pattern typically show a long, narrow face; an open mouth posture; a receding chin; and visible upper front teeth. A 2024 literature review confirmed that adenoid hypertrophy (enlarged adenoids) and chronic oral breathing are associated with these maxillofacial changes, including increased lower face height and a narrower upper jaw. [1]
Adverse oral habits like mouth breathing also affect how the teeth come together. Open bite, where the front teeth do not overlap when the mouth is closed, is a common finding. [4] These changes are not purely cosmetic. Misaligned teeth are harder to clean, which raises the risk of cavities and gum disease over time.
Effects on Sleep, Breathing, and Behavior
Mouth breathing is closely linked to sleep-disordered breathing (SDB), a spectrum that ranges from snoring to obstructive sleep apnea (OSA). Children who mouth breathe often snore, experience restless sleep, and wake up tired. [5]
A 2003 study noted that nasal airway obstruction in children can disturb normal sleep architecture, the pattern of deep and light sleep stages the brain needs for development. Poor sleep quality in children has been associated with daytime fatigue, difficulty concentrating, irritability, and behavioral problems sometimes mistaken for attention deficit hyperactivity disorder (ADHD). [5]
Mouth breathing also dries out the oral tissues. Saliva is the mouth's natural defense system. It washes away food particles, neutralizes acid, and delivers minerals that strengthen enamel. When the mouth is chronically dry, bacteria thrive. This means a higher risk for cavities (dental caries) and gingivitis (gum inflammation). [7]
Age Recommendations, Timing, and Signs to Watch For
The best time to address mouth breathing is during a child's active growth years, typically between ages 5 and 10.
Signs Parents Often Notice
Many parents first notice their child sleeping with the mouth open or snoring. Other common signs include dry or cracked lips, a frequently stuffy nose, dark circles under the eyes (sometimes called allergic shiners), and bad breath, especially in the morning.
At the dentist, certain findings can suggest chronic mouth breathing. These include a narrow upper arch, a high palate, crowded teeth, an anterior open bite, and inflamed gums along the front teeth where air dries the tissue. Your child's dentist may ask questions about sleep quality, snoring, and nasal congestion to connect the dots.
- Sleeping with the mouth open, often with snoring
- Dry, cracked lips and morning bad breath
- Dark circles under the eyes
- Frequent nasal congestion or allergies
- Crowded teeth or a narrow upper jaw on dental exam
- Daytime tiredness, trouble concentrating, or irritability
Why Timing Matters
Facial bones are most responsive to change while they are still growing. The upper jaw (maxilla) develops largely through a process called sutural growth, where the bony seam running down the center of the palate allows the two halves to move apart. This suture begins to fuse in early adolescence, typically around age 12 to 14.
If mouth breathing is addressed before that suture fuses, orthodontic appliances like a palatal expander can physically widen the jaw with relatively predictable results. After the suture fuses, correction may require surgical assistance. This is why the American Academy of Pediatric Dentistry recommends that children have their first dental visit by age 1 and continue regular checkups so problems like mouth breathing can be caught early. [6]
A first orthodontic evaluation is generally recommended around age 7. At that age, a mix of baby teeth and permanent teeth is present. An orthodontist or pediatric dentist can assess jaw width, crossbites, and signs of airway-related growth problems.
What Happens During Evaluation and Treatment
Treatment typically begins with identifying and removing the cause of nasal obstruction, then correcting any dental or skeletal changes that have already occurred.
The Evaluation Process
The first step is usually a visit to the child's pediatrician or an ENT (ear, nose, and throat) specialist. They will examine the nasal passages, adenoids, and tonsils. Imaging, such as a lateral cephalometric X-ray (a side-view head X-ray), may be taken to assess adenoid size and its relationship to the airway. [1]
A dental evaluation happens in parallel. The dentist or orthodontist will examine the bite, measure palate width, look at tooth alignment, and check for crossbites. Dental X-rays and photographs are standard. If a crossbite or narrow palate is found, the provider will discuss orthodontic options.
In some cases, a sleep study (polysomnography) may be recommended. This is an overnight test that monitors breathing, oxygen levels, and brain activity during sleep. It helps determine whether the child has obstructive sleep apnea. [5]
Treating the Airway Obstruction
If enlarged adenoids or tonsils are the primary cause, an adenoidectomy (removal of the adenoids) or adenotonsillectomy (removal of both adenoids and tonsils) may be recommended. These are common outpatient surgeries in children. Once the obstruction is removed, many children naturally begin breathing through the nose again. [1]
For allergy-driven mouth breathing, treatment may include nasal corticosteroid sprays, antihistamines, and allergen avoidance strategies. A deviated septum may need surgical correction (septoplasty), though this is less common in young children. The goal is to restore nasal airflow so the child can close the mouth and breathe comfortably through the nose.
Orthodontic Correction of Jaw and Tooth Changes
Even after the airway is cleared, skeletal and dental changes that already occurred may not reverse on their own. This is where orthodontic treatment comes in.
A rapid palatal expander (RPE) is one of the most commonly used appliances. It is a device cemented to the upper back teeth with a screw mechanism in the center. A parent turns the screw a small amount each day, gradually separating the two halves of the palate. Over several weeks, the upper jaw widens. This creates more room for teeth and can help correct a posterior crossbite. [3]
A Cochrane systematic review on orthodontic treatment for posterior crossbites noted that while expansion appliances are widely used and can correct crossbites, the evidence base for comparing different appliance types remains limited. [3] In practice, palatal expansion is a well-established procedure, but the specific protocol varies by case.
After expansion, some children need braces or aligners to fine-tune tooth position. Myofunctional therapy, a series of exercises that retrain the tongue and facial muscles, may also be recommended. These exercises help the child learn to keep the tongue on the palate, lips closed, and breathe through the nose at rest. While evidence on myofunctional therapy continues to develop, many providers use it as a complementary approach.
Cost Factors for Evaluation and Treatment
The total cost depends on the cause of mouth breathing and which treatments are needed. Costs vary by location, provider, and case complexity.
An ENT consultation typically ranges from $150 to $400 without insurance. If an adenoidectomy or tonsillectomy is needed, surgical costs generally range from $3,000 to $7,000, though medical insurance often covers these procedures when they are medically necessary.
On the dental side, orthodontic evaluation may be offered at no charge or at a low consultation fee. A palatal expander, including the appliance and monitoring visits, typically costs between $1,000 and $3,000. If braces or aligners are needed afterward, treatment may run from $3,000 to $7,000 depending on the complexity and duration. Costs vary by location, provider, and case complexity.
Dental insurance may cover part of orthodontic treatment, especially if it is deemed medically necessary rather than purely cosmetic. Many orthodontic offices offer payment plans. It is worth contacting your insurance provider before treatment to understand your specific coverage and any age limits that apply.
When to See a Specialist
Your child should be evaluated by a specialist if mouth breathing is persistent, not just during a cold or allergy flare.
Start with your child's pediatrician or general dentist. They can screen for the most common causes and refer you to the right specialist. An ENT specialist is the right choice when the concern centers on enlarged adenoids, tonsils, nasal allergies, or structural issues in the nose. [5]
A pediatric dentist or orthodontist should evaluate your child if you notice a narrow upper jaw, crowded teeth, a crossbite, or an open bite. These providers specialize in growth-related dental problems and can determine whether early intervention is appropriate.
Seek evaluation promptly if your child shows any of the following signs. These suggest the mouth breathing may already be affecting development or sleep.
- Nightly snoring or audible breathing during sleep
- Pauses in breathing during sleep (a sign of possible sleep apnea)
- A long, narrow face or receding chin
- Visible crossbite or severely crowded teeth
- Chronic daytime fatigue, difficulty concentrating, or behavioral concerns
- Mouth breathing that persists after a cold has resolved
Find a Pediatric Dentist Near You
If your child breathes through the mouth regularly, a pediatric dentist can assess how it may be affecting jaw growth and tooth alignment. Use our directory to find a pediatric dentist near you who can evaluate your child's bite, airway-related dental changes, and the need for early orthodontic treatment.
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