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 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 (Acute muscular dystonia) after use of Neuroleptics (Anti-Psychotics).

Tongue thrust (also called reverse swallow or immature swallow) is the common name of orofacial muscular imbalance, a human behavioral pattern in which the tongue protrudes through the anterior incisors during swallowing, 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.

OMD refers to abnormal resting posture of the orofacial musculature, atypical chewing, and swallowing patterns, dental malocclusions, blocked nasal airways, and speech problems. OMD are patterns involving oral and/orofacial musculature that interferes with normal growth, development, or function of structures, or calls attention to itself. OMD are found in both children and adults. OMD that are commonly seen in children include tongue thrust that is also known as swallowing with an anterior tongue posture. OMD also refers to factors such as nonnutritive sucking behaviors, such as thumb sucking, clenching, bruxing, etc. that led to abnormal development of dentition and oral cavity. OMD in adult and geriatric population are due to various neurological impairments, oral hygiene, altered functioning of muscles due to aging, systemic diseases, etc.

Tongue thrusting is a type of orofacial myofunctional disorder, which is defined as habitual resting or thrusting the tongue forward and/or sideways against or between the teeth while swallowing, chewing, resting, or speaking. Abnormal swallowing patterns push the upper teeth forward and away from the upper alveolar processes and cause open bites. In children, tongue thrusting is common due to immature oral behavior, narrow dental arch, prolonged upper respiratory tract infections, spaces between the teeth (diastema), muscle weakness, malocclusion, abnormal sucking habits, and open mouth posture due to structural abnormalities of genetic origin. Large tonsils and adenoids also contribute to tongue thrust swallowing.

From the dental perspective, teeth move in relation to the balance of the soft tissue; the normal relationship of teeth lies in occlusion; and any deviation from the normal occlusion can lead to dental distress. Tongue posture plays an important role in swallowing and dentofacial growth. In case of tongue thrust swallowing, the tip of the tongue can come against or between the dentition; the midpoint may be collapsed or extended unilaterally or bilaterally; or the posterior part of the hard palate. In these conditions, there are chances of abnormal dentofacial growth and other concerns regarding development of the craniofacial complex.

There are pertinent symptomatic questions that can be considered for the diagnosis of tongue thrust swallow. Some of these questions are geared toward tongue protrusion and an opening of lips when the client is in repose; habitual mouth breathing; digit sucking; existence of high and narrow palatal arch; ankyloglossia (tongue-tie); malocclusions, (Class II, III); weak chewing muscles (masseter); weak lip muscles (orbicularis oris); overdeveloped chin muscles (mentalis); muscular imbalance; abnormal dentition.

Tongue thrusting and speech problems may co-occur. Due to unconventional postures of the tongue and other articulators, interdental and frontal lisping are very common. The alveolar sounds /s/ and /z/ are produced more anteriorly thus leading to interdental fricative like sounds, /th/.

Orofacial myofunctional disorders (OMD) (sometimes called “oral myofunctional disorder", and “tongue thrust”) are muscle disorders of the face, mouth, lips, or jaw.

Recent studies on incidence and prevalence of tongue thrust behaviors are not available. However, according to the previous research, 38% of various populations have OMD. The incidence is as high as 81% in children exhibiting speech/articulation problems (Kellum, 1992).

Ankyloglossia can affect eating, speech, and oral hygiene as well as have mechanical/social effects. Ankyloglossia can also prevent the tongue from contacting the anterior palate. This can then promote an infantile swallow and hamper the progression to an adult-like swallow which can result in an open bite deformity. It can also result in mandibular prognathism; this happens when the tongue contacts the anterior portion of the mandible with exaggerated anterior thrusts.

According to Horton "et al.", diagnosis of ankyloglossia may be difficult; it is not always apparent by looking at the underside of the tongue, but is often dependent on the range of movement permitted by the genioglossus muscles. For infants, passively elevating the tongue tip with a tongue depressor may reveal the problem. For older children, making the tongue move to its maximum range will demonstrate the tongue tip restriction. In addition, palpation of genioglossus on the underside of the tongue will aid in confirming the diagnosis.

A severity scale for ankyloglossia, which grades the appearance and function of the tongue, is recommended for use in the Academy of Breastfeeding medicine.

Although it may be asymptomatic, symptoms usually are more likely to be present and more severe with larger tongue enlargements. Signs and symptoms include:

- Dyspnea - difficult, noisy breathing, obstructive sleep apnea or airway obstruction

- Dysphagia - difficulty swallowing and eating

- Dysphonia - disrupted speech, possibly manifest as lisping

- Sialorrhea - drooling

- Angular cheilitis - sores at the corners of the mouth

- Crenated tongue - indentations on the lateral borders of the tongue caused by pressure from teeth ("pie crust tongue")

- Open bite malocclusion - a type of malocclusion of the teeth

- Mandibular prognathism - enlarged mandible

- Mouth breathing

- Orthodontic abnormalities - including diastema and tooth spacing

A tongue that constantly protrudes from the mouth is vulnerable to drying out, ulceration, infection or even necrosis.

Examples of congenital disorders which affect the tongue include:

- Aglossia - complete absence of the tongue at birth

- Ankyloglossia (tongue tie) - where the lingual frenum tethers the tongue to the floor of the mouth. If it interferes with oral hygiene and feeding, frenectomy may be indicated.

- Hypoglossia - congenitally short tongue

- Microglossia

- Macroglossia - an abnormally large tongue, seen in some disorders such as Down syndrome (although macroglossia can be an acquired condition as well).

- Hamartomata - for example Leiomyomatous hamartoma

- Glossoptosis

- Choristomata - For example, osseous choristoma of the tongue, a very rare condition characterized by a nodule on the dorsum of the tongue containing mature lamellar bone without osteoblastic or osteoclastic activity. Cartilagenous (chondroid), and glial choristomas may also very rarely occur on the tongue.

- Lingual thyroid

- Cleft tongue (bifid tongue) - completely cleft tongue is a rare condition caused by a failure of the lateral lingual swellings to merge. More common is an incompletely cleft tongue, appearing as midline fissure. This is normally classed as fissured tongue.

Open bite malocclusion can happen due to several reasons. It may be genetic in nature, leading to a skeletal open bite or can be caused by functional habits which may lead to dental open bite. In the earlier age, open bite may occur due to a transitional change from primary to the permanent dentition. Some factors that may cause an open bite are:

- Tongue thrusting

- Thumb sucking

- Long-term usage of Pacifier

- Macroglossia

- Airway obstruction

- Adenoid hypertrophy

- Nasal concha Hypertrophy

The ICD-10 lists macroglossia under "other congenital malformations of the digestive system". Definitions of macroglossia have been proposed, including "a tongue that protrudes beyond the teeth during [the] resting posture" and "if there is an impression of a tooth on the lingual border when the patients slightly open their mouths". Others have suggested there is no objective definition of what constitutes macroglossia. Some propose a distinction between "true macroglossia", when histologic abnormalities correlate with the clinical findings of tongue enlargement, and "relative macroglossia", where histology does not provide a pathologic explanation for the enlargement. Common examples of true macroglossia are vascular malformations, muscular enlargement and tumors; whilst Down syndrome is an example of relative macroglossia. "Pseudomacryglossia" refers to a tongue that is of normal size but gives a false impression of being too large in relation to adjacent anatomical structures. The Myer classification subdivides macroglossia into generalized or localized.

Crenated tongue (also called scalloped tongue, pie crust tongue, lingua indentata, or crenulated tongue) is a descriptive term for the appearance of the tongue when there are indentations along the lateral borders (the sides), as the result of compression of the tongue against the adjacent teeth.

The oral mucosa in the area of crenation is usually of normal color, but there may be erythema (redness) if exposed to a high degree of friction or pressure. Crenated tongue is usually asymptomatic and harmless.

It is not a disease as such, but usually results from habits where the tongue is pressed against the lingual surfaces (the side facing the tongue) of the dental arches, or from any cause of macroglossia (enlarged tongue), which in itself has many causes such as Down syndrome.

Where crenation is caused by parafunctional habits, there may also be associated bruxism, linea alba, or morsicatio buccarum.

An anterior open bite occurs in humans when the front teeth fail to touch and there is no overlap between upper incisors and lower incisors. Anterior open can be caused by functional habits such as digit sucking, tongue thrust or long-term pacifier use. When digit sucking habit is present in the late primary to early mixed dentition stages, it can lead to different side-effects such as upper teeth flaring out, lower teeth flaring in, increase in the open bite and the overjet. A posterior crossbite in these children along with decrease in intercanine and intermolar width is also found. The more intense (longer) the habit, the worse the malocclusion may be.

Pacifier use has also shown to cause anterior open bites in children. Pacifier use which lasts longer than 18 months, may cause this malocclusion. It is shown that as long as the sucking habit stops before the eruption of permanent teeth, the open bite self-corrects. In some cases, behavior modification may be necessary to eliminate the dental habits. If all else fails, then a tongue crib can be used.

By definition, BMS has no signs. Sometimes affected persons will attribute the symptoms to sores in the mouth, but these are in fact normal anatomic structures (e.g. lingual papillae, varices). Symptoms of BMS are variable, but the typical clinical picture is given below, considered according to the Socrates pain assessment method (see table). If clinical signs are visible, then another explanation for the burning sensation may be present. Erythema (redness) and edema (swelling) of papillae on the tip of the tongue may be a sign that the tongue is being habitually pressed against the teeth. The number and size of filiform papillae may be reduced. If the tongue is very red and smooth, then there is likely a local or systemic cause (e.g. eythematous candidiasis, anemia).

Successful treatments have shown that causes are functional rather than physical: that is, most lisps are caused by errors in tongue placement within the mouth rather than caused by any injury or congenital deformity to the mouth. The most frequently discussed of these problems is tongue thrust in which the tongue protrudes beyond the front teeth. This protrusion affects speech as well as swallowing and can lead to lisping. Ankyloglossia or tongue tie can also be responsible for lisps in children.

However, it is unclear whether these deficiencies are caused by the tongue tie itself or the muscle weakness following the correction of the tongue tie. Overbites and underbites may also contribute to non lingual lisping. Temporary lisps can be caused by dental work, dental appliances such as dentures or retainers or by swollen or bruised tongues.

The cause is chronic parafunctional activity of the masticatory system, which produces frictional, crushing and incisive damage to the mucosal surface and over time the characteristic lesions develop. Most people are aware of a cheek chewing habit, although it may be performed subconsciously. Sometimes poorly constructed prosthetic teeth may be the cause if the original bite is altered. Usually the teeth are placed too far facially (i.e. buccally and/or labially), outside the "neutral zone", which is the term for the area where the dental arch is usually situated, where lateral forces between the tongue and cheek musculature are in balance. Glassblowing involves chronic suction and may produce similar irritation of the buccal mucosa. Identical, or more severe damage may be caused by self-mutilation in people with psychiatric disorders, learning disabilities or rare syndromes (e.g. Lesch-Nyhan syndrome and familial dysautonomia).

Snoring is the vibration of respiratory structures and the resulting sound due to obstructed air movement during breathing while sleeping. In some cases, the sound may be soft, but in most cases, it can be loud and unpleasant. Snoring during sleep may be a sign, or first alarm, of obstructive sleep apnea (OSA). Research suggests that snoring is one of the factors of sleep deprivation.

The lesions are located on the mucosa, usually bilaterally in the central part of the anterior buccal mucosa and along the level of the occlusal plane (the level at which the upper and lower teeth meet). Sometimes the tongue or the labial mucosa (the inside lining of the lips) is affected by a similarly produced lesion, termed morsicatio linguarum and morsicatio labiorum respectively. There may be a coexistent linea alba, which corresponds to the occlusal plane, or crenated tongue. The lesions are white with thickening and shredding of mucosa commonly combined with intervening zones of erythema (redness) or ulceration. The surface is irregular, and people may occasionally have loose sections of mucosa that comes away.

The clinical appearance is considerably varied in both the orientation, number, depth and length of the fissure pattern. There are usually multiple grooves/furrows 2–6 mm in depth present. Sometimes there is a large central furrow, with smaller fissures branching perpendicularly. Other patterns may show a mostly dorsolateral position of the fissures (i.e. sideways running grooves on the tongue's upper surface). Some patients may experience burning or soreness.

Tongue diseases can be congenital or acquired, and are multiple in number. Considered according to a surgical sieve, some example conditions which can involve the tongue are discussed below. Glossitis is a general term for tongue inflammation, which can have various etiologies, e.g. infection.

In about 50% of cases of burning mouth sensation no identifiable cause is apparent, these cases are termed (primary) BMS. Several theories of what causes BMS have been proposed, and these are supported by varying degrees of evidence, but none is proven.

As most people with BMS are postmenopausal women, one theory of the cause of BMS is of estrogen or progesterone deficit, but a strong statistical correlation has not been demonstrated. Another theory is that BMS is related to autoimmunity, as abnormal antinuclear antibody and rheumatoid factor can be found in the serum of more than 50% of persons with BMS, but these levels may also be seen in elderly people who do not have any of the symptoms of this condition. Whilst salivary flow rates are normal and there are no clinical signs of a dry mouth to explain a complaint of dry mouth, levels of salivary proteins and phosphate may be elevated and salivary pH or buffering capacity may be reduced.

Depression and anxiety are strongly associated with BMS. It is not known if depression is a cause or result of BMS, as depression may develop in any setting of constant unrelieved irritation, pain, and sleep disturbance. It is estimated that about 20% of BMS cases involve psychogenic factors, and some consider BMS a psychosomatic illness, caused by cancerophobia, concern about sexually transmitted infections, or hypochondriasis.

Chronic low-grade trauma due to parafunctional habits (e.g. rubbing the tongue against the teeth or pressing it against the palate), may be involved. BMS is more common in persons with Parkinson's disease, so it has been suggested that it is a disorder of reduced pain threshold and increased sensitivity. Often people with BMS have unusually raised taste sensitivity, termed hypergeusia ("super tasters"). Dysgeusia (usually a bitter or metallic taste) is present in about 60% of people with BMS, a factor which led to the concept of a defect in sensory peripheral neural mechanisms. Changes in the oral environment, such as changes in the composition of saliva, may induce neuropathy or interruption of nerve transduction. The onset of BMS is often spontaneous, although it may be gradual. There is sometimes a correlation with a major life event or stressful period in life. In women, the onset of BMS is most likely three to twelve years following menopause.

Oromandibular Symptoms

- difficulty opening the mouth (trismus)

- clenching or grinding of the teeth (bruxism)

- spasms of jaw opening

- sideways deviation or protrusion of the jaw

- lip tightening and pursing

- drawing back (retraction) of the corners of the mouth

- deviation or protrusion of the tongue.

- jaw pain

- difficulties eating and drinking

- difficulties speaking (dysarthria)

Blepharospasm symptoms

- the first symptom to appear is an increased rate of blinking

- uncontrollable squinting/closing of eyes

- light sensitivity (photophobia)

- squinting/eyes closing during speech

- uncontrollable eyes closing shut (rare instances completely causing blindness)

In addition, in some patients, the dystonic spasms may sometimes be provoked by certain activities, such as talking, chewing, or biting. Particular activities or sensory tricks may sometimes temporarily alleviate OMD symptoms, including chewing gum, talking, placing a toothpick in the mouth, lightly touching the lips or chin, or applying pressure beneath the chin.

In traditional Chinese medicine, scalloping of the tongue is said to indicate qi vacuity. In some homeopathic sources, scalloping of the tongue is said to be indicative of high blood pressure.

A lisp, also known as sigmatism, is a speech impediment in which a person misarticulates sibilants (, , , ), (, , , ). These misarticulations often result in unclear speech.

In layman's terms, snoring is the result of the relaxation of the uvula and soft palate. These tissues can relax enough to partially block the airway, resulting in irregular airflow and vibrations. Snoring can be attributed to one or more of the following:

- Throat weakness, causing the throat to close during sleep.

- Mispositioned jaw, often caused by tension in the muscles.

- Obesity that has caused fat to gather in and around the throat.

- Obstruction in the nasal passageway.

- Obstructive sleep apnea.

- Sleep deprivation.

- Relaxants such as alcohol or other drugs relaxing throat muscles.

- Sleeping on one's back, which may result in the tongue dropping to the back of the mouth.

The Greek word "blepharon" means "eyelid". Spasm means "uncontrolled muscle contraction". The term blepharospasm ['blef-a-ro-spaz-m] can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette's syndrome to tardive dyskinesia. The blepharospasm referred to here is officially called benign essential blepharospasm (BEB) to distinguish it from the less serious secondary blinking disorders. "Benign" indicates the condition is not life-threatening, and "essential" is a medical term meaning "of unknown cause". It is both a cranial and a focal dystonia. Cranial refers to the head and focal indicates confinement to one part. The word dystonia describes abnormal involuntary sustained muscle contractions and spasms. Patients with blepharospasm have normal eyes. The visual disturbance is due solely to the forced closure of the eyelids.

Oromandibular dystonia (OMD) is a form of focal dystonia that affects varying areas of the head and neck including the lower face, jaw, tongue and larynx. The spasms may cause the mouth to pull open, shut tight, or move repetitively. Speech and swallowing may be distorted. It is often associated with dystonia of the cervical muscles (Spasmodic Torticollis), eyelids (Blepharospasm), or larynx (Spasmodic Dysphonia).

In patients with OMD, involuntary contractions may involve the muscles used for chewing (masticatory muscles). These may include the thick muscle in the cheek that closes the jaw (masseter muscle) and the broad muscle that draws back the lower jaw and closes the mouth (temporalis muscle). Some patients may also experience involuntary contractions of the wide muscle at the side of the neck (platysmal muscle). This muscle draws down the corner of the mouth and lower lip or other muscle groups.