Diagnosis is mainly based on clinical features. However, biopsy has been useful in diagnosis as well as in differentiating between the different types of the disease.

Treatment is symptomatic and may include nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids to reduce swelling, antibiotics and immunosuppressants. Surgery may be indicated to relieve pressure on the facial nerves and reduce swelling, but its efficacy is uncertain. Massage and electrical stimulation may also be prescribed.

BMS is a diagnosis of exclusion, i.e. all other explanations for the symptoms are ruled out before the diagnosis is made. There are no clinically useful investigations that would help to support a diagnosis of BMS (by definition all tests would have normal results), but blood tests and / or urinalysis may be useful to rule out anemia, deficiency states, hypothyroidism and diabetes. Investigation of a dry mouth symptom may involve sialometry, which objectively determines if there is any reduction of the salivary flow rate (hyposalivation). Oral candidiasis can be tested for with use of a swabs, smears, an oral rinse or saliva samples. It has been suggested that allergy testing ("e.g.", patch test) is inappropriate in the absence of a clear history and clinical signs in people with a burning sensation in the mouth. The diagnosis of a people with a burning symptom may also involve psychologic screening e.g. depression questionnaires.

The second edition of the International Classification of Headache Disorders lists diagnostic criteria for "Glossodynia and Sore Mouth":

Macroglossia is usually diagnosed clinically. Sleep endoscopy and imaging may be used for assessment of obstructive sleep apnea. The initial evaluation of all patients with macroglossia may involve abdominal ultrasound and molecular studies for Beckwith–Wiedemann syndrome.

The diagnosis is usually made by tissue biopsy, however this cannot reliably distinguish between the granulomas of OFG and those of Crohn's disease or sarcoidosis. Other causes of granulomatous inflammation are ruled out, such as sarcoidosis,

Crohn's disease, allergic or foreign body reactions and mycobacterial infections.

BMS is benign (importantly, it is not a symptom of oral cancer), but as a cause of chronic pain which is poorly controlled, it can detriment quality of life, and may become a fixation which cannot be ignored, thus interfering with work and other daily activities. Two thirds of people with BMS have a spontaneous partial recovery six to seven years after the initial onset, but in others the condition is permanent. Recovery is often preceded by a change in the character of the symptom from constant to intermittent. No clinical factors predicting recovery have been noted.

If there is an identifiable cause for the burning sensation (i.e. primary BMS), then psychologic dysfunctions such as anxiety and depression often disappear if the symptom is successfully treated.

It is a relatively common condition, with an estimated prevalence of 6.8%–11% amongst children. Males are more commonly affected. The condition may be seen at any age, but generally affects older people more frequently. The condition also generally becomes more accentuated with age. The prevalence of the condition increases significantly with age, occurring in 40% of the population after the age of 40.

Anti-tumour necrosis factor α antagonists (e.g. infliximab)

Dietary restriction of a particular suspected or proven antigen may be involved in the management of OFG, such as cinnamon or benzoate-free diets.

The cause is unknown, but it may be partly a genetic trait. Aging and environmental factors may also contribute to the appearance.

Barium esophagography and videofluoroscopy will help to detect esophageal webs. Esophagogastroduodenoscopy will enable visual confirmation of esophageal webs.

complete blood cell (CBC) counts, peripheral blood smears, and iron studies (e.g., serum iron, total iron-binding capacity [TIBC], ferritin, saturation percentage) to confirm iron deficiency, with or without hypochromic microcytic anemia.

Treatment and prognosis of macroglossia depends upon its cause, and also upon the severity of the enlargement and symptoms it is causing. No treatment may be required for mild cases or cases with minimal symptoms. Speech therapy may be beneficial, or surgery to reduce the size of the tongue (reduction glossectomy). Treatment may also involve correction of orthodontic abnormalities that may have been caused by the enlarged tongue. Treatment of any underlying systemic disease may be required, e.g. radiotherapy.

Plasma cell gingivits is rare, and plasma cell cheilitis is very rare. Most people with plasma cell cheilitis have been elderly.

Histologically plasma cell gingivitis shows mainly plasma cells. The differential diagnosis is with acute leukemia and multiple myeloma. Hence, blood tests are often involved in ruling out other conditions. A biopsy is usually taken, and allergy testing may also be used. The histopathologic appearance is characterized by diffuse, sub-epithelial plasma cell inflammatory infiltration into the connective tissue. The epithelium shows spongiosis. Some consider that plasmoacanthoma (solitary plasma cell tumor) is part of the same spectrum of disease as plasma cell cheilitis.

Tissue biopsy is usually indicated to rule out other causes of white patches and also to enable a detailed histologic examination to grade the presence of any epithelial dysplasia. This is an indicator of malignant potential and usually determines the management and recall interval. The sites of a leukoplakia lesion that are preferentially biopsied are the areas that show induration (hardening) and erythroplasia (redness), and erosive or ulcerated areas. These areas are more likely to show any dysplasia than homogenous white areas.

Brush biopsy/exfoliative cytology is an alternative to incisional biopsy, where a stiff brush is scraped against the lining of the mouth to remove a sample of cells. This is then made into a smear which can be examined microscopically. Sometimes the biopsy site can be selected with adjunct methods which aim to highlight areas of dysplasia. Toluidine blue staining, where the dye is preferentially retained by dysplastic tissue, is sometimes used, but there is high false positive rate. Other methods involve the use of illuminescence, relying on either the property of normal autoflorescent molecules in mucosa such as collagen and keratin which is lost from areas of dysplasia or carcinoma under blue light, or by initially staining of the mucosa with toluidine blue or dilute acetic acid and examination under white light.

Good oral hygiene (thorough tooth brushing and flossing and regular professional cleaning and examination) may be helpful to prevent these disorders. Drinking plenty of water and the production of enough saliva, aid in the reduction of bacterial growth. Minimizing irritants or injury in the mouth when possible can aid in the prevention of glossitis. Avoiding excessive use of any food or substance that irritates the mouth or tongue may also help.

This condition is considered premalignant because it may lead to squamous cell carcinoma in about 10% of all cases. It is not possible to predict which cases will progress into SCC, so the current consensus is that all lesions should be treated.

Treatment options include 5-fluorouracil, imiquimod, scalpel vermillionectomy, chemical peel, electrosurgery, and carbon dioxide laser vaporization. These curative treatments attempt to destroy or remove the damaged epithelium. All methods are associated with some degree of pain, edema, and a relatively low rate of recurrence.

Chronic ulcerative stomatitis is a recently discovered condition with specific immunopathologic features. It is characterized by erosions and ulcerations which relapse and remit. Lesions are located on the buccal mucosa (inside of the cheeks) or on the gingiva (gums). The condition resembles Oral lichen planus when biopsied.

The diagnosis is made with Immunofluorescence techniques, which shows circulating and tissue-bound autoantibodies (particulate stratified squamous-epithelium-specific antinuclear antibody) to DeltaNp63alpha protein, a normal component of the epithelium. Treatment is with hydroxychloroquine.

To prevent AC from developing, protective measures could be undertaken such as avoiding mid-day sun, or use of a broad-brimmed hat, lip balm with anti UVA and UVB ingredients (e.g. para-aminobenzoic acid), or sun blocking agents (e.g. zinc oxide, titanium oxide) prior to sun exposure.

The diagnosis is usually made based upon the clinical appearance, and swabs can be taken of the surface of the denture. Investigations to rule out possibility of diabetes may be indicated. Tissue biopsy is not usually indicated, but if taken shows histologic evidence of proliferative or degenerative responses and reduced keratinization and epithelial atrophy.

Angular cheilitis could be considered to be a type of cheilitis or stomatitis. Where Candida species are involved, angular cheilitis is classed as a type of oral candidiasis, specifically a primary (group I) Candida-associated lesion. This form angular cheilitis which is caused by Candida is sometimes termed "Candida-associated angular cheilitis", or less commonly, "monilial perlèche". Angular cheilitis can also be classified as acute (sudden, short-lived appearance of the condition) or chronic (lasts a long time or keeps returning), or refractory (the condition persists despite attempts to treat it).

Angular chielitis is normally a diagnosis made clinically. If the sore is unilateral, rather than bilateral, this suggests a local factor ("e.g.", trauma) or a split syphilitic papule. Angular cheilitis caused by mandibular overclosure, drooling, and other irritants is usually bilateral.

The lesions are normally swabbed to detect if Candida or pathogenic bacterial species may be present. Persons with angular cheilitis who wear dentures often also will have their denture swabbed in addition. A complete blood count (full blood count) may be indicated, including assessment of the levels of iron, ferritin, vitamin B12 (and possibly other B vitamins), and folate.

A lesion biopsy is performed if the diagnosis remains uncertain after a clinical physical exam. The most common tissue sampling techniques include shave or punch biopsy. When only a portion of the lesion can be removed due to its size or location, the biopsy should sample tissue from the thickest area of the lesion, as SCCs are most likely to be detected in that area. If a shave biopsy is performed, it should extend through to the level of the dermis in order to provide sufficient tissue for diagnosis; ideally, it would extend to the mid-reticular dermis. Punch biopsy usually extends to the subcutaneous fat when the entire length of the punch blade is utilized.

Leukoplakia has a wide range of possible histologic appearances. The degree of hyperkeratosis, epithelial thickness (acanthosis/), dysplasia and inflammatory cell infiltration in the underlying lamina propria are variable. In mucous membranes, hyperkeratosis can be defined as "an increase in the thickness of the keratin layer of the epithelium, or the presence of such a layer in a site where none would normally be expected." In leukoplakia, the hyperkeratosis varies in thickness, and may be either ortho- or para-keratosis, (depending upon whether cell nuclei are lost or retained in the superficial layers respectively), or a mixture of both in different areas of the lesion.

The epithelium may show hypertrophy (e.g. acanthosis) or atrophy. Red areas within leukoplakia represent atrophic or immature epithelium which has lost the ability to keratinize. The transition between the lesion and normal surrounding mucosa may be well demarcated, or poorly defined. Melanin, a pigment naturally produced in oral mucosa, can leak from cells and give a grey color to some leukoplakia lesions.

Hyperkeratosis and altered epithelial thickness may be the only histologic features of a leukoplakia lesion, but some show dysplasia. The word "dysplasia" generally means "abnormal growth", and specifically in the context of oral red or white lesions refers to microscopic changes ("cellular atypia") in the mucosa that indicate a risk of malignant transformation. When dysplasia is present, there is generally an inflammatory cell infiltration in the lamina propria. The following are commonly cited as being possible features of epithelial dysplasia in leukoplakia specimens:

- Cellular pleomorphism, in which cells are of abnormal and different shapes.

- Nuclear atypia, in which the nuclei of cells varies in size, any may be increased in size relative to the cytoplasm, shape, and may stain more intensely. There may also be more prominent nucleoli.

- Increased number of cells seen undergoing mitosis, including both normal and abnormal mitoses. Abnormal mitosis may be abnormally located, e.g. occurring in suprabasal cells (cell layers more superficial to the basal cell layer) or of abnormal form, e.g. "tri-radiate mitoses" (a cell splitting into 3 daughter cells rather than only 2)

- Loss the normal organization of the epithelial layers. The distinction between the epithelial layers may be lost. Normally stratified squamous epithelium shows progressive changes in the form of cells from the basal to the superficial layers, with cells becoming more flat ("squames") towards the surface as a continuous maturation process. In dysplastic epithelium, cells may become vertically orientated rather than becoming flat towards the surface.

- There may be abnormal keratinization, where keratin is formed below the normal keratin layer. This can occur in individual cells or groups of cells, forming an intraepithelial keratin pearl. There may be an increase in number of basal cells, and they may lose their cellular orientation (losing their polarity and long axis).

- Alteration of the normal epithelial-connective tissue architecture - the rete pegs may become "drop shaped". wider at their base than more superficially.

Generally dysplasia is subjectively graded by pathologists into mild, moderate or severe dysplasia. This requires experience as it is a difficult skill to learn. It has been shown that there is high degree of inter-observer variation and poor reproducibility in how dysplasia is graded. Severe dysplasia is synonymous with the term carcinoma in situ, denoting the presence of neoplastic cells which have not yet penetrated the basement membrane and invaded other tissues.

Dermoscopy is a noninvasive technique utilizing a handheld magnifying device coupled with a transilluminating lift. It is often used in the evaluation of cutaneous lesions, but lacks the definitive diagnostic ability of biopsy-based tissue diagnosis. Histopathologic exam remains the gold standard