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.
For example, according to recent literature, as many as 67–95 percent of children 5–8 years old exhibit tongue thrust, which may professionally be represented as associated with or contributing to an orthodontic or speech problem – depending on the clinical bias of proposal.
Up to the age of four years, as with the complex conversion of all simpler reflex events, there is a possibility that any observed child will normally outgrow tongue thrust as they transition to a fuller dentofacial development.
An anterior open bite is a common malocclusion associated with this type of tongue thrusting pattern, especially in the presence of lip incompetence.
Bilateral thrust:[citation needed] This occurs when the tongue pushes between the back teeth on both sides during the swallow with the jaw partially open.
Many orthodontists have completed dental treatment with what appeared to be good results, only to discover that the case relapsed because of the patient's tongue thrust.
While a study by Cleall (1965) found that 70% of adolescents with malocclusion exhibit tongue thrusting, Subtelny et al. (1964) reported this number as 42%.
A study by Fletcher et al. (1961) reported that two-thirds of children between 6 and 18 years with tongue thrusting showed sigmatism.
Appliance therapy is most effective when used during growth and requires up to 6 months to resolve tongue thrusting and anterior open bite.