Articles

In order to breathe well, the airway has to be unobstructed and patent. This allow the air to flow from the nasal passage, through the pharyngeal airway and to the lung smoothly. We take it for granted that this is always the case for everyone. However, individuals with retrognathic mandible or a retruded, narrow lower jaw will beg to differ. They usually have a more Vshaped upper jaw too, indicating smaller nasal airway. Their bites are deep as well, with little showing of the lower teeth.

An underdeveloped lower jaw will not have sufficient space for the tongue to rest forward during swallowing, which happens a few thousand times a day. The tongue is forced backwards and narrows down the lumen at the back of the throat. To overcome this the head is postured forward to drop the jaw to breathe. They gasp air through the mouth as nose breathing becomes laborious. Mouth breathing becomes dominant and further complicates the malocclusion as the tongue is drawn back. Overall posture will be affected with the head-neck alignment going off-tangent and skeletal deformities ensue. Form will follow function. With less use of the nasal portion, proper facial development can be impacted in early childhood and have lasting negative effects.

During sleep, the natural resting position of the jaw and relaxed tongue posed a bigger problem. Without voluntary control, muscle tonicity drops and the tongue flops back and obstruct the airway to greater extent, causing a reduction in airflow commonly associated with snoring to complete upper airway obstruction with periodic cessation of breathing (OSA – Obstructive Sleep Apnea). They will continue to mouth breath during sleep but with less efficiency. This can leads to low oxygenation of the blood and related bruxism. Frequent arousal during the sleep cycles and disturbances in sleep pattern affect the quality of sleep and restfulness. Daytime sleepiness can be both embarrassing when one dozes of during meeting or school or life-endangering when one is behind the wheel of the car.

So how can we help as dentists to improve the situation? Children with malocclusion usually have an under developed upper jaw and a retrognathic lower jaw and have an underlying orthopaedic cause.

Before the age of 12, with mixed dentitions, we can already use appliances in the mouth to help with growth and development. It will help to expand the maxilla to improve nasal airway and increase the perimeter for the teeth to grow and erupt into. Functional appliances used in the growing child will reposition the mandible and improve head posture. The increase in oral volume also allow the tongue to come forward and influence the proper development of the lower arch.

With early intervention, we create a better prospect for the teeth and jaw to form properly and reduce the complexity or even the need for future orthodontic treatment.

For adults, the gold standard for assessing severity of OSA is obtained by a sleep study or polysomnogram (PSG). Those with diagnosed sleep apnea, continuous positive airway pressure (CPAP) may be prescribed. However, with underlying anatomical limitation not resolved, it is still not treating the root cause of the problem. Some cannot tolerate CPAP at all, mandible advancement device MAD can be considered. The lower jaw is held forward with such dental appliances to allow air to flow better but again the root issue is not addressed. Most with sleep disorders also exhibit signs and symptoms of temporomandibular disorder (TMD) like headaches, joint pain and tinnitus. The American Academy of Craniofacial Pain recommends dentists managing OSA with MAD should have experience in treating TMD patients so as to provide better prognosis and treatment outcomes.

Some of these problems can be corrected permanently with expansion and rounding of the arches orthodontically in conjunction with gneuromuscular concepts to improve oral volume and airway. The whole dynamic relationship of the jaw, joints, muscles and airway will be considered to determine an ideal treatment position so as to reduce obstruction and ensure airflow in the open channels, bring forth a good night sleep for a healthier you.

Dr Yue Weng Cheu
BDS (Singapore)
FRACDS (Australia)
MJDF RCS (England)

Founder and Clinical Director
DP Dental Pte Ltd
Heartland Mall, Level 3 (Kovan MRT)