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.

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.

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.

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 could be considered to be a type of glossitis. It usually presents only on the dorsal 2/3 and lateral surfaces of the tongue, but less commonly an identical condition can occur on other mucosal sites in the mouth, such as the ventral surface (undersurface) of the tongue, mucosa of the cheeks or lips, soft palate or floor of mouth; usually in addition to tongue involvement. In such cases, terms such as stomatitis erythema migrans, ectopic geographic tongue, areata migrans, geographic stomatitis, or migratory stomatitis are used instead of geographic tongue. Beside the differences in locations of presentation inside the oral cavity and prevalence among the general population, in all other aspects of clinical significance, symptoms, treatment, and histopathologic appearance, these two forms are identical.

This condition is sometimes termed (oral) erythema migrans, but this has no relation to the more common use of the term erythema migrans (erythema chronicum migrans), to describe the appearance of skin lesions in Lyme disease.

Fissured tongue (also known as "scrotal tongue," "lingua plicata," "Plicated tongue," and "furrowed tongue") is a benign condition characterized by deep grooves (fissures) in the dorsum of the tongue. Although these grooves may look unsettling, the condition is usually painless. Some individuals may complain of an associated burning sensation.

It is a relatively common condition, with a prevalence of between 6.8% and 11% found amongst children. Often hereditary, may also be part of degenerative process. The prevalence of the condition increases significantly with age, occurring in 40% of the population after the age of 40.

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.

It presents itself in the mouth, most frequently as a thick, bilateral, symmetrical white plaques with a spongy, corrugated or velvety texture. Most usually, the lesions are on the buccal mucosa, but sometimes on the labial mucosa, alveolar ridge, floor of the mouth, ventral surface of the tongue or soft palate. The gingival margin and dorsum of the tongue are almost never affected. Less commonly, sites outside the mouth are affected, including the nasal, esophageal, laryngeal, anal and genital mucosae. It usually is present from birth, or develops during childhood. Rarely, the lesions may develop during adolescence. Apart from the appearance of the affected areas, there are usually no other signs or symptoms.

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.

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).

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.

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.

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.

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.

White sponge nevus (WSN, or white sponge naevus, Cannon's disease, hereditary leukokeratosis of mucosa, white sponge nevus of Cannon, familial white folded dysplasia, or oral epithelial nevus), is an autosomal dominant condition of the oral mucosa (the mucous membrane lining of the mouth). It is caused by a mutations in certain genes coding for keratin, which causes a defect in the normal process of keratinization of the mucosa. This results in lesions which are thick, white and velvety on the inside of the cheeks within the mouth. Usually, these lesions are present from birth or develop during childhood. The condition is entirely harmless, and no treatment is required.

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.

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

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.

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).

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/.

Talon Cusp will show physical signs of the irregular dental formation of the teeth and cause other symptoms of the disease that could possibly lead to dental problems in the future depending on severity of the deformity. Most commonly, the extra cusp is located on the lingual surface, giving a three-pronged appearance which has been described as an eagle talon. Rarely however the extra cusp may be situated on the facial surface, or there may be extra cusps on both lingual and facial surfaces. There may be a deep groove between the talon cusp and the rest of the tooth. The extra cusp typically contains pulp tissue. When viewing talon cusp from the occlusal, the projection will appear "x-shaped" as well as appears conical and mimicking the shape of an "eagle's talon".

Symptoms of talon cusp include:

- Interference with occlusion or bite

- Irritation of soft tissues and tongue

- Accidental cusp fracture

- Susceptible to dental caries

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).

This anomaly is large enough to be seen with the naked eye. One can see the projection on the incisal edge of a tooth looking into the mouth of the affected person. The structure is described to be "T'shaped" or "X-shaped" however will differ depending on its shape, size, structure, location and site of origin. X-rays and radiographs can also show evidence of the abnormality. The digital images would show a tooth with talon cusp as if it were "double teeth".

When looking at a radiograph some features to look for would be location, edge, shape and number. The location would be on an anterior tooth, the edge would be clear and well defined and can be seen even by the naked eye, and the shape would appear "talon-like" over the top portion or crown of the affected tooth. There could potentially be one, two or multiple protrusions depending on the type of cusp.

Talon cusp can fall under three categories: Type I, Type II and Type III. They are created based on the cusp formation shape and length of extension.

- Type I - Talon: The additional cusp or talon projects from the palatal surface of a primary or permanent anterior (front) tooth that extends at least half of the distance from the cemento enamel junction to the incisal edge.

- Type II - Semi Talon: The semi talon cusp measures about 1mm or more in length but extends less than half of the distance seen in Type I Talon.

- Type III - Trace Talon: The projection originates from the cingulum (also known as the "cervical third") of the root and is enlarged or prominent in any form (conical, or tubercle-like)

Since many cases of Talon cusp go unreported, it is hard to draw linkage maps but it is safe to assume that dental formation is influenced by genetic factors. Talon cusp is also seen in association with conditions such as Rubinstein-Taybi syndrome, Mohr syndrome, Ellis–van Creveld syndrome, Incontinentia pigmenti achromians, Berardinelli-Seip syndrome, and Sturge–Weber syndrome.

Tongue thrust is normal in infants until approximately the age of six months. The loss of this normal infant behavior is one of the signs that the baby is ready to begin eating baby food.

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 (1.8 kg) of pressure each time. If a person suffers from tongue thrusting, this continuous pressure tends to force the teeth out of alignment. Many people who tongue thrust have 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. 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 is not frequently affected by the tongue thrust swallowing pattern. The "S" sound (lisping) is the one most affected. The lateral lisp (air forced on the side of the tongue rather than forward) shows dramatic improvement when the tongue thrust is corrected. However, lisping and tongue thrust are not always associated.

Congenital disorders of the salivary glands are rare, but may include:

- Aplasia

- Atresia

- Ectopic salivary gland tissue

- Stafne defect - an uncommon condition which some consider to be an anatomic variant rather than a true disease. It is thought to be created by an ectopic portion of salivary gland tissue which causes the bone of the mandible to remodel around the tissue, creating an apparent cyst like radiolucent area on radiographs. Classically, this lesion is discovered as a chance finding, since it causes no symptoms. It appears below the inferior alveolar nerve canal in the posterior region of the mandible.