What Causes Crooked Teeth?

If you’re a parent, you’ve probably wondered if your child will need orthodontic braces. It’s a worry because braces are expensive, inconvenient – and not popular with your child! But as a parent, of course you want your child to have a straight smile. You can see the long-term health and cosmetic benefits.

Children’s orthodontics is one way to straighten a smile. But the uncertainty of braces is now being alleviated by a better understanding of dental arch growth.

The functional role of the face and teeth are key to your child’s dental health and normal development. To grow a straight adult dental arch, your child’s jaw and cranial bones must develop properly.

What’s the age for seeing an orthodontist?

Currently, the American Academy of Orthodontics recommend that children should see an orthodontist at age 7.

But here’s the problem. The causes of crooked teeth usually begin long before 7 years of age. A child’s jaw development is going into its finalstages by age 7. The causes of a crooked jaw and/or teeth can stem from developmental issues that begin at birth – or even before!

Functional dentistry can now help to identify and address these causes of crooked teeth.

Myofunctional therapy and orofacial myology are two fields concerned with correcting these issues in children. But you may be able to at least identify some of your child’s dental problems yourself, if you know what to look for.

Ways to help your kids grow straight teeth

Key factors in healthy jaw growth and straight teeth include:

  • Nasal breathing
  • Tongue position
  • Lip posture
  • Skeletal posture

If your child has an unusual posture or breathes mainly through their mouth, they may have a facial muscle or development disorder. This can be due to a cascade of events at critical points in your child’s growth.

When a child is referred to an orthodontist at age 12 – or even 7 – these problems may have been present for many years. In fact, every breath, meal and posture can affect the development of your child’s jaw and teeth. This in turn affects their chances of getting or avoiding braces.

What are ‘crooked’ teeth?

Generally, crooked teeth are classified by the pediatric dentist or orthodontist.

Here are some broad classifications:

Cross bites

Where one of the top back teeth bites down inside the bottom back teeth. Cross bites are more common among children who snore.

There are two types of cross-bite:

  • Anterior cross bite
Anterior Cross Bite
  • Posterior cross bite (more common in mouth breathers)
Posterior Cross Bite

Anterior open bite

The upper and lower front teeth don’t meet, leaving a gap, but the back teeth bite together. This is most commonly due to thumb sucking or a functional habit.

Anterior Open Bite

Class II malocclusion

When the lower teeth sit too far behind the upper teeth. It has been found to be more common in mouth breathers.

Class II Malocclusion

Common Cause #1: Incorrect Skeletal, Jaw and Teeth Development

Jaw development

Developing a wide palate is key to a child’s healthy teeth and jaw development.

Cranial imbalances can involve the skull, jaw, and vertebral bones. The development of the upper jaw or palate is the main factor directing the growth of these bones.

Maxilla or upper jaw

This houses the upper teeth, the hard palate and the lower border of the orbit (eye socket). The maxilla is the center of facial growth. Its development is driven by both nasal breathing and tongue posture.

Signs of an undergrown maxilla:

  • High, thin, V-shaped palate
  • Thin, long face (from the front)
  • Lack of cheek bones
  • Sunken midface or nose (from side-on profile view)
  • Droopy or uneven eyes
  • Crooked upper teeth (from age 7 plus)

The narrow palate and upper jaw distorts the nasal airway by lengthening the pharynx and decreases the nasal airway volume.

These changes are a risk factor for obstructive sleep apnea. Dental arch narrowing in children can increase risk of snoring and sleep apnea symptoms.

Mandible or lower jawbone

This houses the tongue and connects to your skull via the temporomandibular jaw joint (TMJ).

Signs of an undergrown mandible:

  • Retruded chin
  • Rounded jawline
  • A lack of forward growth in the upper and lower jaws
  • A side profile with jawline that swings down and backwards into the airway

Common Cause #2: Nasal airway obstruction

Nasal breathing is central to proper jaw and teeth development.

In one day you will take between 20 000 to 30 000 breaths. Normal breathing provides the forces that expand the maxilla and upper jaw.

If a child has a chronic blocked sinus or nasal obstruction, they may form a mouth breathing habit. It only takes a slight obstruction to increase pressure in the nasal airway and cause a child to revert to open mouth breathing.

Causes for nasal blockages and a chronic blocked sinus include:

  • Sinus infections
  • Enlarged nasal turbinates
  • Deviated septum
  • Swollen tonsils and adenoids
  • Chronic upper airway infections
  • Allergies
  • The tongue falling into the airway during sleep

An assessment with an ear nose and throat (ENT) surgeon to assess the nasal airways is an important part of normal childhood facial development.

Common Cause #3: Incorrect Tongue Posture

In proper tongue posture, we should see the tongue up against the palate. The tip and back of the tongue should be pressed upwards to the palate. This activates all the muscles that connect to the jaw, the base of the skull, the spine and the throat.

A low and forward tongue posture indicates that your child’s tongue isn’t being pressed up against the palate correctly.

One of the best times to check your child’s tongue posture is when they are watching television. What do they do with their tongue? Can you see it? Do they poke it out?

Also consider:

  • Do they have a tongue thrust when they speak?
  • Do they have a lisp or speech impediment?
  • Do they have a tongue-tie? This can prevent your child from achieving a high tongue posture. You can check normal tongue vs tongue-tie in this article.
  • Is their palate narrow or V-shaped?

Swallowing incorrectly by straining facial muscles

During correct swallowing, the tongue should perform a wave motion across the palate. The motion exerts a widening, forward and upwards force, expanding the maxilla.

A child should have straight spinal posture, closed lips and nasal breathing when eating, swallowing and at rest. Watch your child’s normal swallow. Can they swallow food comfortably with their teeth together? If it looks uncomfortable for them, it’s likely they have some form of incorrect swallow.

Dysphagia or incorrect swallow

The most common form of incorrect swallow is a tongue-thrust swallow. This is where the tongue comes forward between the teeth during the swallow instead of against the palate.

Signs your child has an incorrect swallow:

  • Their front teeth are held slightly apart with their tongue placed between them.
  • There is an inadequate lip seal at rest.
  • Cheek and chin muscles are used as compensation, which suck against the dentition. This puts a contraction force on the face and palate.
  • Chubby cheeks. The buccinator ring – the group of facial muscles including your lips and cheeks – may become overdeveloped due to incorrect swallowing. It can result in bulging or chubby cheeks.

Common Cause #4: Poor Lip Posture

Your child’s facial muscles should close the lips at rest. If their lips don’t sit together at rest, it’s often due to a low and forward tongue posture.

Signs of lip incompetence:

  • The lower lip is more likely to show flaccidity or floppiness than the upper lip. A flaccid lower lip that lacks adequate muscle tone will appear droopy and it can appear to roll forward.
  • Muscle strain is seen over the chin or mentalis muscles as lips are brought into contact. You will see muscle dimpling/buckling in the skin overlying the vertically-positioned mentalis muscles. These muscles are below the corners of the lower lip, extending downward to an area lateral to the chin. By contrast, a normal lips-together rest posture should have no activation of the mentalis strain.

Common Cause #5: Oral behaviors

Certain non-nutritive sucking and oral behaviors can signal an oral development impairment.

  • Thumb sucking and chewing habits
  • Pacifiers

Many parents ask if pacifiers can make their baby’s teeth crooked. The answer is yes – pacifiers can cause an open bite. But the good news is, there’s plenty of time to correct oral behaviors in your child.

Crooked Teeth Can Be Prevented!

The causes of crooked teeth in children can begin from birth. By identifying proper oral function, you can correct your child’s habits before they cause malocclusion. This can help your child avoid braces in future – and grow a straight, strong smile!

Do you have any questions regarding your child’s bite? Leave them in the comment section below.

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