Tongue thrust (also called reverse swallow or immature swallow) is a pseudo-pathological name of what is either considered a normal adaptive lip seal mechanism, whereby normal nasal breathing or normal swallowing can occur. Or, it is seen as an oral myofunctional disorder - a tongue muscle pattern that is perceived as clinically abnormal and in which the tongue protrudes anteriorly to seal otherwise incompetent lips. [Source: Wikipedia 
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