Tongue thrust
Tongue thrust is the common name of an oral myofunctional disorder, a dysfunctional muscle pattern in which the tongue protrudes anteriorly or laterally during swallowing, during speech, and while the tongue is at rest. Nearly all infants exhibit a swallowing pattern involving tongue protrusion, but by six months of age most lose this reflex allowing for the ingestion of solid foods.
Since 1958, the term "tongue thrust" has been described and discussed in speech and dental publications by many writers. Many school-age children have tongue thrust. For example, according to recent literature, as many as 67–95 percent of children 5–8 years old exhibit tongue thrust, which may be associated with or contributing to an orthodontic or speech problem. Up to the age of four, there is a possibility that the child will outgrow tongue thrust. However, if the tongue thrust swallowing pattern is retained beyond that age, it may be strengthened.
| Name | Definition |
| Anterior thrust | This is the most common type of tongue thrust. It is often associated with a low, forward tongue rest posture. Sometimes the tongue can be seen protruding beyond the lips at rest and/or during the swallow. Upper incisors can be extremely protruded and the lower incisors are pulled in by the lower lip. An anterior open bite is a common malocclusion associated with this type of tongue thrusting pattern, especially in the presence of lip incompetence. This type of thrust is most generally accompanied by a strong mentalis. |
| Unilateral thrust | This occurs when the tongue pushes unilaterally to the side between the back teeth during the swallow. The bite can be characteristically open on that side. |
| Bilateral thrust | This occurs when the tongue pushes between the back teeth on both sides during the swallow. Sometimes, the only teeth that touch are the molars, with the bite completely open on both sides including the anterior teeth. A large tongue can also be noted. This is the most difficult thrust to correct. |
Causes
Factors that can contribute to tongue thrusting include macroglossia, thumb sucking, large tonsils, hereditary factors, ankyloglossia, and certain types of artificial nipples used in feeding infants, also allergies or nasal congestion can cause the tongue to lie low in the mouth because of breathing obstruction and finally contributing to tongue thrusting. In addition, it is also seen after prolonged therapy by levodopa in Parkinsonism, also it occurs as extra pyramidal side effect after use of neuroleptics.Effects
Tongue extrusion is normal in infants.Tongue thrusting can adversely affect the teeth and mouth. A person swallows from 1,200 to 2,000 times every 24 hours with about four pounds of pressure each time. If a person suffers from tongue thrusting, this continuous pressure tends to force the teeth out of alignment. People who exhibit a tongue thrust often present with open bites; the force of the tongue against the teeth is an important factor in contributing to "bad bite". 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. If the tongue is allowed to continue its pushing action against the teeth, it will continue to push the teeth forward and reverse the orthodontic work.
Speech may be affected by a tongue thrust swallowing pattern. Sounds such as /s/, /z/, /t/, /d/, /n/, and /l/ are produced by placing the tongue on the upper alveolar ridge, and therefore a tongue thrust may distort these sounds.
Chewing and swallowing with dysfunctional muscle patterning is not as effective as a normal chewing and swallowing motion.