Tongue thrust

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Tongue thrust, also called reverse swallow or immature swallow, is a pseudo-pathological name for an adaptive lip seal mechanism, whereby normal nasal breathing or normal swallowing can occur. Tongue thrust can also be seen as an oral myofunctional disorder, a tongue muscle pattern that is perceived as clinically abnormal, in which the tongue protrudes anteriorly to seal the otherwise incompetent lips.

Tongue thrusting is seen during speech, swallowing or eating, and in order to close otherwise incompetent lips and anterior open bite. In normal suckling behavior, infants have their tongues positioned between their gum pads anteriorly resting on the lower lip, which facilitates infantile (i.e. visceral) swallowing pattern.  As teeth start to erupt and solid foods are introduced, pharyngeal muscles, posterior tongue, and elevator muscles of the lower jaw play a role in the swallowing pattern. As the child's primary molars erupt, swallowing follows a somatic pattern characterized by the contact of the molars, tongue positioning behind the maxillary incisors, and relaxation of the perioral muscles. Atypical swallowing patterns can arise when there is a failure in the fore-mentioned normal maturation of swallowing.^[1]

There are thus two view-points regarding tongue thrusting behaviour that persists past the neonatal period.

1. Tongue thrusting is an adaptive means of closing an open (or incompetent) lip state, caused by a unique combination of anatomical reasons, or
2. Tongue thrusting is the cause or potentiator of an open or incompetent lip state, which resists efforts at behavioural change or clinical attempt at remedy.

In generality, tongue thrusting is poorly understood. In particular it lacks consensus on many points of description, causality, effect or management.