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

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.

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.

Posterior open bite is caused when posterior teeth such as molars or premolars fail to touch their counterpart tooth. This is more likely to occur in segments where there may be unilateral open bite or open bite related to one or more teeth. Failure of eruption of teeth either due to primary failure or mechanical obstruction during eruption phase can cause the open bite. Sometimes lateral tongue thrust may also prevent the eruption of the posterior teeth, thus eliminating this habit maybe key to eruption in those instances.

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).

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.

Hairy tongue largely occurs in the central part of the dorsal tongue, just anterior (in front) of the circumvallate papillae, although sometimes the entire dorsal surface may be involved. Discoloration usually accompanies hairy tongue, and may be yellow, brown or black. Apart from the appearance, the condition is typically asymptomatic, but sometimes people may experience a gagging sensation or a bad taste. There may also be associated oral malodor (intra-oral halitosis).

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.

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/.

While identifying the causes of tongue thrust, it is important to remember that the resting posture of the tongue, jaw, and lips are crucial to normal development of mouth and its structures. If tongue rests against the upper front teeth, the teeth may protrude forward, and adverse tongue pressure can restrict the development of the oral cavity. The tongue lies low in the mouth or oral cavity and is typically forwarded between upper and lower teeth. If tongue thrust behavior is not corrected, it may affect the normal dental development. The teeth may be pushed around in different directions during the growth of permanent teeth.

In health, the dorsal surface of the tongue is covered in tuft like projections called lingual papillae (some of which are associated with taste buds), which give the tongue an irregular surface texture and a white-pink color. Geographic tongue is characterized by areas of atrophy and depapillation (loss of papillae), leaving an erythematous (darker red) and smoother surface than the unaffected areas. The depapillated areas are usually well demarcated, and bordered by a slightly raised, white, yellow or grey, serpiginous (snaking) peripheral zone. A lesion of geographic tongue may start as a white patch before the depapillation occurs. In certain cases there may be only one lesion, but this is uncommon; the lesions will typically occur in multiple locations on the tongue and coalesce over time to form the typical map-like appearance. The lesions usually change in shape, size and migrate to other areas, sometimes within hours. The condition may affect only part of the tongue, with a predilection for the tip and the sides of the tongue, or the entire dorsal surface at any one time. The condition goes through periods of remission and relapse. Loss of the white peripheral zone is thought to signify periods of mucosal healing.

There are usually no symptoms other than the unusual appearance of the tongue, but in some cases persons may experience pain or burning e.g. when eating hot, acidic, spicy or other kinds of foods (e.g. cheese, tomatoes, fruit). Where there is a burning symptom, other causes of a burning sensation on the tongue are considered, such as oral candidiasis.

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.

Hairy tongue (lingua villosa) refers to a marked accumulation of keratin on the filiform papillae on the dorsal surface of the tongue, giving a hair-like appearance. Black tongue (lengua negra) refers to a black discoloration of the tongue, which may or may not be associated with hairy tongue. However, the elongated papillae of hairy tongue usually develop discoloration due to growth of pigment producing bacteria and staining from food. Hence the term black hairy tongue, although hairy tongue may also be discolored yellow or brown. Transient, surface discoloration that is not associated with hairy tongue can be brushed off. Drug-induced black hairy tongue specifically refers to BHT that develops because of medication.

A great many diseases involve the mouth, jaws and orofacial skin. Some example pathologies which can involve the oral and maxillofacial region are listed. Some are more common than others, and this list is by no means complete. The examples are considered according to a surgical sieve.

Oral and maxillofacial pathology (also termed oral pathology, stomatognathic disease, dental disease, or mouth disease) refers to the diseases of the mouth ("oral cavity" or "stoma"), jaws ("maxillae" or "gnath") and related structures such as salivary glands, temporomandibular joints, facial muscles and perioral skin (the skin around the mouth). The mouth is an important organ with many different functions. It is also prone to a variety of medical and dental disorders.

The specialty oral and maxillofacial pathology is concerned with diagnosis and study of the causes and effects of diseases affecting the oral and maxillofacial region. It is sometimes considered to be a specialty of dentistry and pathology. Sometimes the term head and neck pathology is used instead, but this might imply that the pathologist deals with otorhinolaryngologic disorders (i.e. ear, nose and throat) in addition to maxillofacial disorders. In this role there is some overlap between the expertise of head and neck pathologists and that of endocrine pathologists.

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.

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).

Depending upon what exact meaning of the word glossitis is implied, signs and symptoms might include:

- Smooth, shiny appearance of the tongue, caused by loss of lingual papillae.

- Tongue color changes, usually to a darker red color than the normal white-pink color of a healthy tongue.

- Tongue swelling.

- Difficulty with chewing, swallowing, or speaking (either because of tongue soreness of tongue swelling).

- Burning sensation. Some use the term secondary burning mouth syndrome in cases where a detectable cause, such as glossitis, for an oral burning sensation.

Depending upon the underlying cause, there may be additional signs and symptoms such as pallor, oral ulceration and angular cheilitis.

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.

Geographic tongue, also known by several other terms, is an inflammatory condition of the mucous membrane of the tongue, usually on the dorsal surface. It is a common condition, affecting approximately 2–3% of the general population. It is characterized by areas of smooth, red depapillation (loss of lingual papillae) which migrate over time. The name comes from the map-like appearance of the tongue, with the patches resembling the islands of an archipelago. The cause is unknown, but the condition is entirely benign (importantly, it does not represent oral cancer), and there is no curative treatment. Uncommonly, geographic tongue may cause a burning sensation on the tongue, for which various treatments have been described with little formal evidence of efficacy.

The name "lie bumps" is a result of a myth that telling lies would cause them. However, very little has been written about this condition in scientific articles or textbooks and scientific studies have failed to produce a definite cause. Possible causes include: "stress, gastrointestinal upset, menstruation, acidic or sour food, smoking, and local trauma" (direct physical irritation) of the tongue. Lie bumps are often caused by the taste bud(s) splitting.

These bumps are small, white bumps on the base of the tongue. They are likely to be the result of transient lingual papillitis (TLP). This condition is limited to the upper (dorsal) surface of the tongue, affecting some of the tiny bumps on the tongue known as the fungiform papillae, what we commonly call the "taste buds."

TLP is a harmless problem. These bumps can become notably red or white and are quite tender for up to several days. While the cause of TLP is not known with certainty, most experts feel that local accidental trauma (rubbing, scraping or biting) is a major factor; however, contact reactions to things like certain foods have also been suggested. Lie bumps are not contagious and the discomfort is relatively minor. Typically these lesions heal within a few days with no treatment, though a doctor may refer a patient to an oral pathologist in prolonged cases.

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.

Geographic tongue, also termed benign migratory glossitis, is a common condition which usually affects the dorsal surface of the tongue. It is characterized by patches of depapillation and erythema bordered by a whitish peripheral zone. These patches give the tongue the appearance of a map, hence the name. Unlike glossitis due to nutritional deficiencies and anemia, the lesions of geographic tongue move around the tongue over time. This is because in geographic tongue, new areas of the tongue become involved with the condition whilst previously affected areas heal, giving the appearance of a moving lesion. The cause is unknown, and there is no curative treatment. Rarely are there any symptoms associated with the lesions, but occasionally a burning sensation may be present, which is exacerbated by eating hot, spicy or acidic foodstuffs. Some consider geographic tongue to be an early stage of fissured tongue, since the two conditions often occur in combination.

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.