The lesion is usually painless. The usual appearance is of two excess tissue folds in alveolar vestibule/buccal sulcus, with the flange of the denture fitting in between the two folds. It may occur in either the maxillary or mandibular sulci, although the latter is more usual. Anterior locations are more common than posterior. Less commonly there may be a single fold, and the lesion may appear on the lingual surface of the mandibular alveolar ridge.

The swelling is firm and fibrous, with a smooth, pink surface. The surface may also show ulceration or erythema. The size of the lesion varies from less than 1 cm to involving the entire length of the sulcus.

The cause is usually pressure from the flange of a denture which causes chronic irritation and a hyperplastic response in the soft tissues. Women during pregnancy can also present with an epulis, which will resolve after birth. Fibroepithelial polyps, pedunculated lesions of the palate beneath an upper denture, are associated with this condition. A cobble-stone appearance similar to an epulis fissuratum in a patient without dentures can be diagnostic of Crohn's disease. Epulis fissuratum can also appear around dental implants.

This type of epulis is neither pyogenic ("pus producing") nor a true granuloma, but it is a vascular lesion. About 75% of all pyogenic granulomas occur on the gingiva, although they may also occur elsewhere in the mouth or other parts of the body (where the term epulis is inappropriate). This common oral lesion is thought to be a reaction to irritation of the tissues and poor oral hygiene. It is more common in younger people and in females, and appears as a red-purple swelling and bleeds easily.

This is a fibrous hyperplasia of excess connective tissue folds that takes place in reaction to chronic trauma from an ill fitting denture. It usually occurs in the mandibular labial sulcus. Sometimes the term "epulis" is used synonymously with epulis fissuratum, but this is technically incorrect as several other lesions could be described as epulides.

The appearance of pyogenic granuloma is usually a color ranging from red/pink to purple, and can be smooth or lobulated. Younger lesions are more likely to be red because of the high number of blood vessels. Older lesions begin to change into a pink color. Size commonly ranges from a few millimeters to centimeters, though smaller or larger lesions may occur. A pyogenic granuloma can be painful, especially if located in an area of the body where it is constantly disturbed. Pyogenic granulomas can grow rapidly and will often bleed profusely with little or no trauma. They may exude an oil like substance, causing the surface to be damp. This is especially true if the granuloma is located on the scalp.

Pyogenic granulomas may be seen at any age, and are more common in females than males. In pregnant women, lesions may occur in the first trimester with an increasing incidence up until the seventh month, and are often seen on the gums. Epulis granulomatosum is a variant of pyogenic granuloma that forms only on gingiva, and is often seen forming in a recent extraction socket. Pyogenic granulomas appear on the gingiva in 75% of cases, more often in the maxillary than mandibular jaw. Anterior areas are more often affected than posterior areas. It can also be found on the lips, tongue, and inner cheek. Poor oral hygiene or trauma are usually precipitating factors.

One study has suggested a correlation between pyogenic granulomas and Bartonella seropositivity. However, this association has been questioned by others. The microscopic appearance of a pyogenic granuloma consists of highly vascular granulation tissue. Inflammation is present. The lesion may have a fibrous character if it is older, and the surface may have ulcerations. Pyogenic granulomas rarely occur in the conjunctiva, cornea or connective tissue of the eye following minor local trauma. Grossly these mass lesions resemble those occurring at more common sites. The relationship of these lesion to lobular capillary hemangiomas of skin and oropharyngeal mucosa commonly referred to as pyogenic granuloma is uncertain.

Rarely is any soreness associated with the condition. Apart from the appearance of the lesion, there are usually no other signs or symptoms. The typical appearance of the lesion is an oval or rhomboid shaped area located in the midline of the dorsal surface of the tongue, just anterior (in front) of the sulcus terminalis. The lesion is usually symmetric, well demarcated, erythematous and depapillated, which has a smooth, shiny surface. Less typically, the lesion may be hyperplastic or lobulated and exophytic. There may be candidal lesions at other sites in the mouth, which may lead to a diagnosis of chronic multifocal oral candidiasis. Sometimes an approximating erythematous lesion is present on the palate as the tongue touches the palate frequently. The lesion is typically 2–3 cm in its longest dimension.

Pyogenic granuloma (also known as a "eruptive hemangioma", "granulation tissue-type hemangioma", "granuloma gravidarum", "lobular capillary hemangioma", "pregnancy tumor", and "tumor of pregnancy") is a vascular lesion that occurs on both mucosa and skin, and appears as an overgrowth of tissue due to irritation, physical trauma, or hormonal factors. It is often found to involve the gums, the skin and nasal septum, and has also been found far from the head such as in the thigh.

The terms gingival hyperplasia and gingival hypertrophy have been used to describe this topic in the past. These are not precise descriptions of gingival enlargement because these terms are strictly histologic diagnoses, and such diagnoses require microscopic analysis of a tissue sample. Hyperplasia refers to an increased number of cells, and hypertrophy refers to an increase in the size of individual cells. As these identifications obviously cannot be performed with a clinical examination and evaluation of the tissue, the term "gingival enlargement" is more properly applied. Gingival enlargement has been classified according to cause into 5 general groups:

- Inflammatory enlargement

- Drug induced enlargement

- Enlargement associated with systemic diseases or conditions

- Neoplastic enlargement

- False enlargement.

Predisposing factors include smoking, denture wearing, use of corticosteroid sprays or inhalers and human immunodeficiency virus (HIV) infection. "Candida" species even in healthy people mainly colonizes the posterior dorsal tongue. Median rhombiod glossitis is thought to be a type of chronic atrophic (or erythematous) candidiasis. Microbiological culture of the lesion usually shows "Candida" mixed with bacteria.

Gingival enlargement may be caused by a multitude of causes. The most common is chronic inflammatory gingival enlargement, when the gingivae are soft and discolored. This is caused by tissue edema and infective cellular infiltration caused by prolonged exposure to bacterial plaque, and is treated with conventional periodontal treatment, such as scaling and root planing.

Gingivitis and gingival enlargement are often seen in mouth breathers, as a result of irritation brought on by surface dehydration, but the manner in which it is caused has not been demonstrated.

The accumulation and retention of plaque is the chief cause of inflammatory gingival enlargement. Risk factors include poor oral hygiene, as well as physical irritation of the gingiva by improper restorative and orthodontic appliances.

Most cases of leukoplakia cause no symptoms, but infrequently there may be discomfort or pain. The exact appearance of the lesion is variable. Leukoplakia may be white, whitish yellow or grey. The size can range from a small area to much larger lesions. The most common sites affected are the buccal mucosa, the labial mucosa and the alveolar mucosa, although any mucosal surface in the mouth may be involved. The clinical appearance, including the surface texture and color, may be homogenous or non-homogenous (see: classification). Some signs are generally associated with a higher risk of cancerous changes (see: prognosis).

Leukoplakia may rarely be associated with esophageal carcinoma.

Peripheral ossifying fibroma “a gingival nodule which is composed of a cellular fibroblastic connective tissue stroma which is associated with the formation of randomly dispersed foci of mineralised products, which consists of bone, cementum-like tissue, or a dystrophic calcification. The lesion is considered part of an ossifying fibroma, but that is usually considered to be a gnathic tumor. Because of its overwhelming incidence on the gingiva, the condition is associated with two other diseases, though not because they occur together. Instead, the three are associated with each other because they appear frequently on gingiva: pyogenic granuloma and peripheral giant cell granuloma. Some researchers believe peripheral ossifying fibromas to be related to pyogenic fibromas and, in some instances, are the result of a pyogenic granuloma which has undergone fibrosis and calcification.

The term "peripheral ossifying fibroma" has been criticized as this lesion is not related to the ossifying fibroma of bone and is not a fibroma. This term is used in America, however in Britain, this lesion would be termed a fibrous epulis containing bone.

In the context of lesions of the mucous membrane lining of the bladder, leukoplakia is a historic term used to describe a visualized white patch which histologically represents keratinization in an area of squamous metaplasia. The symptoms may include frequency, suprapubic pain (pain felt above the pubis), hematuria (blood in the urine), dysuria (difficult urination or pain during urination), urgency, and urge incontinence. The white lesion may be seen during cystoscopy, where it appears as a whitish-gray or yellow lesion, on a background of inflamed urothelium and there may be floating debris in the bladder. Leukoplakia of the bladder may undergo cancerous changes, so biopsy and long term follow up are usually indicated.

The color of peripheral ossifying fibromas ranges from red to pink, and is frequently ulcerated. It can be sessile or pedunculated with the size usually being less than 2 cm. Weeks or months may pass by before it is seen and diagnosed.

There is a gender difference with 66% of the disease occurring in females. The prevalence of peripheral ossifying fibromas is highest around 10 – 19 years of age. It appears only on the gingiva, more often on the maxilla rather than the mandible, and is frequently found in the area around incisors and canines. The adjacent teeth are usually not affected.

Peripheral ossifying fibromas appear microscopically as a combination of a mineralized product and fibrous proliferation. The mineralized portion may be bone, cementum-like, or dystrophic calcifications. Additionally, highly developed bone or cementum is more likely to be present when the peripheral ossifying fibroma has existed for a longer period of time.

The palate may appear gray or white and contain many papules or nodules that are slightly elevated with red dots in their center. These red dots represent the ducts of minor salivary glands which have become inflamed by heat. The condition is painless. If a denture is normally worn while smoking, then the mucosa underneath the denture appears unaffected by the condition. In severe cases, the mucosa may show fissuring and develop a "dried lake bed" appearance. Other changes associated with tobacco use may be evident such as brown or black extrinsic staining of teeth from tar and other components of tobacco smoke.

Also called smoker's palatal keratosis, this condition may occur in smokers, especially pipe smokers. The palate appears dry and cracked, and white from keratosis. The minor salivary glands appear as small, red and swollen bumps. It is not a premalignant condition, and the appearance reverses if the smoking is stopped.

Plasma cell cheilitis is a very rare presentation of a condition which more usually occurs on the gingiva (termed "plasma cell gingivitis") or sometimes the tongue. Plasma cell cheilitis appears as well defined, infiltrated, dark red plaque with a superficial lacquer-like glazing. Plasma cell cheilitis usually involves the lower lip. The lips appear dry, atrophic and fissured. Angular cheilitis is sometimes also present.

Buccal exostoses are considered different entities to osteomas (e.g. seen in Gardner syndrome), even though the two lesions are histopathologically identical.

The term "necrotizing ulcerative gingivostomatitis" is sometimes used as a synonym of the necrotizing periodontal disease more commonly termed necrotizing ulcerative gingivitis, or a more severe form (also termed necrotizing stomatitis). The term "necrotizing gingivostomatitis" is also sometimes used.

Regional odontodysplasia or odontogenesis imperfecta is an uncommon developmental abnormality of teeth, usually localized to a certain area of the mouth. The condition is nonhereditary. There is no predilection for race, but females are more likely to get regional odontodysplasia. The enamel, dentin, and pulp of teeth are affected, to the extent that the affected teeth do not develop properly. These teeth are very brittle. On radiographs the teeth appear more radiolucent than normal, so they are often described as "ghost teeth". Most cases are considered , but some cases are associated with syndromes, growth abnormalities, neural disorders, and vascular malformations.

Permanent teeth usually show effects of regional odontodysplasia if the deciduous tooth was affected. Many of these teeth do not erupt, and those that do have an increased risk of caries and periapical inflammation.

Despite the alternative name for this condition, "denture sore mouth", it is usually painless and asymptomatic. The appearance of the involved mucosa is erythematous (red) and edematous (swollen), sometimes

with petechial hemorrhage (pin-points of bleeding). This usually occurs beneath an upper denture. Sometimes angular cheilitis can coexist, which is inflammation of the corners of the mouth, also often associated with "Candida albicans". Stomatitis rarely develops under a lower denture. The affected mucosa is often sharply defined, in the shape of the covering denture.

Stomatitis nicotina (also known as nicotine stomatitis, nicotinic stomatitis, nicotine palatinus, stomatitis palatini, leukokeratosis nicotina palate, palatal leukokeratosis, smoker's keratosis, smoker's palate, and smoker's patches), is a diffuse white patch on the hard palate, usually caused by tobacco smoking, usually pipe or cigar smoking. It is painless, and it is caused by a response of the palatal oral mucosa to chronic heat. A more pronounced appearance can occur with reverse smoking, sometimes distinguished from stomatitis nicotina by the term reverse smoker's keratosis. While stomatitis nicotina that is caused by heat is not a premaligant condition (i.e. it does not carry an increased risk of transformation to oral cancer), the condition that is caused by reverse smoking is premalignant.

The Newton classification divides denture-related stomatitis into three types based on severity. Type one may represent an early stage of the condition, whilst type two is the most common and type three is uncommon.

- Type 1 - Localized inflammation or pinpoint hyperemia

- Type 2 - More diffuse erythema (redness) involving part or all of the mucosa which is covered by the denture

- Type 3 - Inflammatory nodular/papillary hyperplasia usually on the central hard palate and the alveolar ridge

Congenital epulis is a proliferation of cells most frequently occurring on the alveolar ridge of the upper jaw at birth. Less frequently the mass may arise from the mandibular alveolus. Rare cases can arise from the tongue. This lesion is more commonly found in female babies, suggesting hormonal involvement during embryonic development. The cause of this type of epulis is unknown. Also known as congenital granular cell tumor or Neumann's tumor; historically referred to as granular cell myoblastoma.

Multiple lesions occur in 10% of affected neonates. The tumor is typically pedunculated and varies in maximum size from 0.5 cm to 9 cm. The lesion is typically painless and does not increase in size after discovery. Some small lesions may regress over time. Treatment is surgical excision. Recurrence is extremely rare even after incomplete excision.

True hyposalivation may give the following signs and symptoms:

- Dental caries (xerostomia related caries) – Without the anticariogenic actions of saliva, tooth decay is a common feature and may progress much more aggressively than it would otherwise ("rampant caries"). It may affect tooth surfaces that are normally spared, e.g., cervical caries and root surface caries. This is often seen in patients who have had radiotherapy involving the major salivary glands, termed radiation-induced caries.

- Acid erosion. Saliva acts as a buffer and helps to prevent demineralization of teeth.

- Oral candidiasis – A loss of the antimicrobial actions of saliva may also lead to opportunistic infection with "Candida" species.

- Ascending (suppurative) sialadenitis – an infection of the major salivary glands (usually the parotid gland) that may be recurrent. It is associated with hyposalivation, as bacteria are able to enter the ductal system against the diminished flow of saliva. There may be swollen salivary glands even without acute infection, possibly caused by autoimmune involvement.

- Dysgeusia – altered taste sensation (e.g., a metallic taste) and dysosmia, altered sense of smell.

- Intraoral halitosis – possibly due to increased activity of halitogenic biofilm on the posterior dorsal tongue (although dysgeusia may cause a complaint of nongenuine halitosis in the absence of hyposalivation).

- Oral dysesthesia – a burning or tingling sensation in the mouth.

- Saliva that appears thick or ropey.

- Mucosa that appears dry.

- A lack of saliva pooling in the floor of the mouth during examination.

- Dysphagia – difficulty swallowing and chewing, especially when eating dry foods. Food may stick to the tissues during eating.

- The tongue may stick to the palate, causing a clicking noise during speech, or the lips may stick together.

- Gloves or a dental mirror may stick to the tissues.

- Fissured tongue with atrophy of the filiform papillae and a lobulated, erythematous appearance of the tongue.

- Saliva cannot be "milked" (expressed) from the parotid duct.

- Difficulty wearing dentures, e.g., when swallowing or speaking. There may be generalized mucosal soreness and ulceration of the areas covered by the denture.

- Mouth soreness and oral mucositis.

- Lipstick or food may stick to the teeth.

- A need to sip drinks frequently while talking or eating.

- Dry, sore, and cracked lips and angles of mouth.

- Thirst.

However, sometimes the clinical findings do not correlate with the symptoms experienced. E.g., a person with signs of hyposalivation may not complain of xerostomia. Conversely a person who reports experiencing xerostomia may not show signs of reduced salivary secretions (subjective xerostomia). In the latter scenario, there are often other oral symptoms suggestive of oral dysesthesia ("burning mouth syndrome"). Some symptoms outside the mouth may occur together with xerostomia.

These include:

- Xerophthalmia (dry eyes).

- Inability to cry.

- Blurred vision.

- Photophobia (light intolerance).

- Dryness of other mucosae, e.g., nasal, laryngeal, and/or genital.

- Burning sensation.

- Itching or grittiness.

- Dysphonia (voice changes).

There may also be other systemic signs and symptoms if there is an underlying cause such as Sjögren's syndrome, for example, joint pain due to associated rheumatoid arthritis.