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The Importance of Jaw Growth & Development

“From the first day, all through life, the jaws help maintain the vital human airway” - Essentials of Facial Growth 1996


  • A baby’s jaw is almost 50% of its adult size at birth*

  • Children’s occlusions (bites) are already apparent from around 18 months to 2 years of age

  • By 6 years of age, jaws are almost 80% of their adult size, with most of the growth occurring in the first 4 years.


Early Orthopaedic Influences on Jaws and Face
*The health and nutrition of the mother, genetic factors and cranial trauma during the birth play their part in the first half of jaw development.

The most important positive influence on infant jaw development is exclusive breastfeeding.
Apart from the nutritional and financial benefits, Breast is Best because:

  • It involves all the peri-oral musculature and the tongue in a complex, coordinated effort;

  • The tongue motion is peristaltic during swallowing – this is critical to the proper development of the oral cavity, airway shape and facial form;

  • Tongue action during feeding (whether by breast or bottle) is continued into adult life;

  • Infants can breathe and breastfeed at the same time due to the ability of the epiglottis to interlock with the soft palate.


Why Exclusive Breastfeeding?
Early introductions of solids can produce allergies because solids cannot be properly digested until more teeth are present, and allergies lead to airway problems which lead to malocclusion and facial imbalance.

Why some babies can’t breastfeed

  • Shape of palate at birth – cleft, bubble, high vault

  • Prematurity – underdeveloped epiglottis

  • Tongue-tie – can be relieved with simple laser surgery

  • Early allergies – inhibiting nose breathing


Early Negative Orthopaedic Influences

  • Mouth breathing produces:

    • Low tongue posture

    • Incorrect swallow pattern

    • Overdeveloped mandible (sometimes – can produce a long face)

    • Underdeveloped maxilla – tongue must go to the palate with every swallow in order to develop the maxilla

    • Anterior open bite – when combined with tongue thrust

    • Ear problems, tonsil/adenoid inflammation

    • Speech problems


  • Bottle Feeding can result in an abnormal swallow pattern (tongue thrust) and an anterior open bite (no overlap between upper and lower incisor teeth) Incorrect swallow pattern leads to underdeveloped maxilla.

  • Dummy or thumb sucking – if excessive does the same as bottle feeding.

  • Continuous sucking on anything firmer than a breast will distalise the tongue, which can elevate the soft palate and block the openings of the Eustachian tubes, increase risk of SIDS and ear problems.

  • If tongue action is adversely affected, the shape of airway, jaws and facial form are also affected.

  • Allowing a baby to sleep only on one side, especially with a hand caught under the jaw, can result in crossbite.


What is involved in Early Orthodontic Treatment?

Elimination of oral habits – thumb/finger sucking, dummy, bottle dependent.

Assessment of tonsils and adenoids

Parents aren’t always aware of their child’s tonsillar problems because chronically large tonsils may not be infected and don’t always cause pain

Sometimes parents are just aware of slow or noisy eating.

Difficult to get GPs to refer as they base referrals on number of acute cases of tonsillitis/year but dentists/orthodontists can refer directly to ENTs if they explain that airway problems are contributing to orthontic problems.

  • Bite opening

    • Buildups using tooth coloured filling material to lengthen molars will increase vertical dimension, makes more room for the tongue and allows the mandible to develop, repositions mandibular condyles taking pressure off ears and jaw joint discs

“Children with deep dental overbites are 2.8 times more likely to have ear tubes (ear grommets) placed or recommended by a pediatric otolaryngologist” The Laryngoscope – 2001

Myofunctional Appliance (Munchy)

  • Best started around 3 years of age, used daily and slept with if possible.

  • Used to improve peri-oral muscle tone and balance, correct swallow pattern, train tongue to go to the roof of mouth, encourage nose breathing.

  • Additional benefits – helps to keep teeth and gums clean, stimulates salivation to buffer acids and aid digestion.

  • Can only be used if nose breathing is possible and tonsils are not so enlarged that they’re pushing tongue anteriorly

  • Most effective for crossbites, open bites and Class IIIs (mandible developing faster than maxilla)


Orthopaedic Orthodontics is started as early as possible and usually completed in two phases of treatment. In the first phase, the child’s jaw growth is monitored and guided to achieve the best possible facial balance and jaw relationship. Treatment is planned to stimulate growth where it is deficient, to redirect it where its direction is wrong and to moderate it where it is excessive. Bringing the mandible forwards, developing the maxilla, opening the bite are examples of functional orthodontics.
Depending on the emotional maturity of the child and the cooperative level of parents, functional orthodontic treatment can be started as early as 3 years of age.

Windows of opportunity for using Removable Orthodontic Appliances (plates)

  • 4 to 6 years (once baby incisors are lost, the appliance will be too unstable)

  • 8 to 10 years (before baby molars get loose)

Fixed functional appliances are also used but require more attention to oral hygiene.
Myofunctional appliances can be used in conjunction with orthodontic appliances to help keep teeth and gums clean.


The 2nd Phase (braces) is more about the teeth and so is not usually started until most of the adult teeth have erupted. It provides the fine-tuning necessary to produce optimal positioning of each individual tooth in the dental arch.

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