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.
Tongue thrusting is an adaptive means of closing an open (or incompetent) lip state, caused by a unique combination of anatomical reasons, or
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.
Types of Tongue Thrust
Both the general dental and speech pathologist classical views are that tongue thrusting causes both the dentofacial abnormality of anterior open bite, and the incompetent lip seal and swallowing and speech effects associated with tongue thrust.
In both professions, tongue thrust is represented as a behavioural disturbance which can be taught to be resisted. Such interventional therapy is represented to strongly assist orthodontic or speech pathologist efforts at resolution of both the speech and orthodontic effects of anterior open bite and the associated lip incompetence or both.
As with normal reflexes, at an early 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 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. However, if a tongue thrust pattern is retained beyond infancy, it can be seen through a lens of abnormality.
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.
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.
This occurs when the tongue pushes between the back teeth on both sides during the swallow with the jaw partially open.
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
There is lack of good quality evidence regarding the causes of tongue thrusting. Factors that can contribute to tongue thrusting include macroglossia (enlarged tongue), thumb sucking, large tonsils, hereditary factors, ankyloglossia (tongue tie), 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 contribute to tongue thrusting.[citation needed]
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 4 pounds (1.8kg) of pressure each time. If a person has 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" (malocclusion). 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.[citation needed] 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.
Malocclusion:
The link between atypical swallowing and dental malocclusion is controversial. 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%.[3]
Speech:
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.[4] However, evidence on the link between tongue thrusting and misarticulation of /s/ and /z/ sounds, also known as sigmatism or lisping, is controversial. A study by Fletcher et al. (1961) reported that two-thirds of children between 6 to 18 years with tongue thrusting showed sigmatism.[5] On the other hand, there are other studies that found no significant difference between children with or without atypical swallowing in lisping.[6]
Chewing and swallowing with dysfunctional muscle patterning (as in a tongue thrust) is not as effective as a normal chewing and swallowing motion.
Treatment
Appliance therapy, and myofunctional therapeutic exercises are among the treatment options for tongue thrusting:
Management of non-nutritive sucking habits such as thumb-sucking as well as mouth breathing may correct tongue thrusting.
Tongue cribs and functional appliances can correct tongue thrusting by leading to a more posteriorly position of the tongue.[citation needed] Tongue spurs are also effective options in the treatment of tongue thrust which work by triggering pain when the tongue is positioned forward. Appliance therapy is most effective when used during growth and requires up to 6 months to resolve tongue thrusting and anterior open bite.
Myofunctional therapeutic exercises work by increasing the individual’s awareness about the positioning of their tongue and aim to correct its positioning.[citation needed]
Overall, it is important to note that there is no good quality evidence in the literature regarding tongue thrusting.
Orthodontics is a dentistry specialty that addresses the diagnosis, prevention, management, and correction of mal-positioned teeth and jaws, as well as misaligned bite patterns. It may also address the modification of facial growth, known as dentofacial orthopedics.
Hyperdontia is the condition of having supernumerary teeth, or teeth that appear in addition to the regular number of teeth. They can appear in any area of the dental arch and can affect any dental organ. The opposite of hyperdontia is hypodontia, where there is a congenital lack of teeth, which is a condition seen more commonly than hyperdontia. The scientific definition of hyperdontia is "any tooth or odontogenic structure that is formed from tooth germ in excess of usual number for any given region of the dental arch." The additional teeth, which may be few or many, can occur on any place in the dental arch. Their arrangement may be symmetrical or non-symmetrical.
Prognathism is a positional relationship of the mandible or maxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in the coronal plane of the skull.
In orthodontics, a malocclusion is a misalignment or incorrect relation between the teeth of the upper and lower dental arches when they approach each other as the jaws close. The English-language term dates from 1864; Edward Angle (1855–1930), the "father of modern orthodontics", popularised it. The word "malocclusion" derives from occlusion, and refers to the manner in which opposing teeth meet.
Oral myology is the field of study that involves the evaluation and treatment of the oral and facial musculature, including the muscles of the tongue, lips, cheeks, and jaw.
Thumb sucking is a behavior found in humans, chimpanzees, captive ring-tailed lemurs, and other primates. It usually involves placing the thumb into the mouth and rhythmically repeating sucking contact for a prolonged duration. It can also be accomplished with any organ within reach and is considered to be soothing and therapeutic for the person. As a child develops the habit, it will usually develop a "favourite" finger to suck on.
Tooth eruption is a process in tooth development in which the teeth enter the mouth and become visible. It is currently believed that the periodontal ligament plays an important role in tooth eruption. The first human teeth to appear, the deciduous (primary) teeth, erupt into the mouth from around 6 months until 2 years of age, in a process known as "teething". These teeth are the only ones in the mouth until a person is about 6 years old creating the primary dentition stage. At that time, the first permanent tooth erupts and begins a time in which there is a combination of primary and permanent teeth, known as the mixed dentition stage, which lasts until the last primary tooth is lost. Then, the remaining permanent teeth erupt into the mouth during the permanent dentition stage.
Occlusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as occurs during chewing or at rest.
Overjet is the extent of horizontal (anterior-posterior) overlap of the maxillary central incisors over the mandibular central incisors. In class II malocclusion the overjet is increased as the maxillary central incisors are protruded.
Crossbite is a form of malocclusion where a tooth has a more buccal or lingual position than its corresponding antagonist tooth in the upper or lower dental arch. In other words, crossbite is a lateral misalignment of the dental arches.
Dental pertains to the teeth, including dentistry. Topics related to the dentistry, the human mouth and teeth include:
Orofacial myofunctional disorders (OMD) are muscle disorders of the face, mouth, lips, or jaw due to chronic mouth breathing.
Overbite is the extent of vertical (superior-inferior) overlap of the maxillary central incisors over the mandibular central incisors, measured relative to the incisal ridges.
Serial extraction is the planned extraction of certain deciduous teeth and specific permanent teeth in an orderly sequence and predetermined pattern to guide the erupting permanent teeth into a more favorable position.
In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.
Activator Appliance is an Orthodontics appliance that was developed by Viggo Andresen in 1908. This was one of the first functional appliances that was developed to correct functional jaw in the early 1900s. Activator appliance became the universal appliance that was used widely throughout Europe in the earlier part of the 20th century.
Intrusion is a movement in the field of orthodontics where a tooth is moved partially into the bone. Intrusion is done in orthodontics to correct an anterior deep bite or in some cases intrusion of the over-erupted posterior teeth with no opposing tooth. Intrusion can be done in many ways and consists of many different types. Intrusion, in orthodontic history, was initially defined as problematic in early 1900s and was known to cause periodontal effects such as root resorption and recession. However, in mid 1950s successful intrusion with light continuous forces was demonstrated. Charles J. Burstone defined intrusion to be "the apical movement of the geometric center of the root (centroid) in respect to the occlusal plane or plane based on the long axis of tooth".
Open bite is a type of orthodontic malocclusion which has been estimated to occur in 0.6% of the people in the United States. This type of malocclusion has no vertical overlap or contact between the anterior incisors. The term "open bite" was coined by Carevelli in 1842 as a distinct classification of malocclusion. Different authors have described the open bite in a variety of ways. Some authors have suggested that open bite often arises when overbite is less than the usual amount. Additionally, others have contended that open bite is identified by end-on incisal relationships. Lastly, some researchers have stated that a lack of incisal contact must be present to diagnose an open bite.
Orthodontic indices are one of the tools that are available for orthodontists to grade and assess malocclusion. Orthodontic indices can be useful for an epidemiologist to analyse prevalence and severity of malocclusion in any population.
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