Salivary gland diseases (SGDs) are multiple and varied in cause. There are three paired major

salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary ...

s in humans – the

parotid gland The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the ma ...

s, the submandibular glands, and the sublingual glands. In addition there are about 800-1000 minor salivary glands in the mucosa of the mouth. The parotid gland is located in front of each

ear An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...

, and secretes mostly

serous In physiology, serous fluid or serosal fluid (originating from the Medieval Latin word ''serosus'', from Latin ''serum'') is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The flu ...

saliva via the

parotid duct The parotid duct, or Stensen duct, is a salivary duct. It is the route that saliva takes from the major salivary gland, the parotid gland, into the mouth. Structure The parotid duct is formed when several interlobular ducts, the largest ducts in ...

(Stenson duct) into the mouth, usually opening roughly opposite the

maxillary second molar The maxillary second molar is the tooth located distally (away from the midline of the face) from both the maxillary first molars of the mouth but mesial (toward the midline of the face) from both maxillary third molars. This is true only in pe ...

. The submandibular gland is located medial to the angle of the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, and it drains its mixture of serous and

mucous Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

saliva via the submandibular duct (Wharton duct) into the mouth, usually opening in a punctum located in the floor of mouth. The sublingual gland is located below the tongue, on the floor of the mouth. It drains its mostly mucous saliva into the mouth via about 8-20 ducts which open along the plica sublingualis (a fold of tissue under the tongue). The function of the salivary glands is to secrete saliva, which has a lubricating function, which protects the oral mucosa of the mouth during eating and speaking. Saliva also contains

digestive enzyme Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption into the cells of the body. Digestive enzymes are found in the digestive tracts of anima ...

s (e.g. salivary

amylase An amylase () is an enzyme that catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of ...

) and has

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

action and acts as a

buffer Buffer may refer to: Science * Buffer gas, an inert or nonflammable gas * Buffer solution, a solution used to prevent changes in pH * Buffering agent, the weak acid or base in a buffer solution * Lysis buffer, in cell biology * Metal ion buffer * ...

. Salivary gland dysfunction occurs when salivary rates are reduced and this can result in

xerostomia Xerostomia, also known as dry mouth, is dryness in the mouth, which may be associated with a change in the composition of saliva, or reduced salivary flow, or have no identifiable cause. This symptom is very common and is often seen as a side eff ...

(dry mouth). Various examples of disorders affecting the salivary glands are listed below. Some are more common than others, and they are considered according to a surgical sieve, but this list is not exhaustive.

Sialadenitis Sialadenitis (sialoadenitis) is inflammation of salivary glands, usually the major ones, the most common being the parotid gland, followed by submandibular and sublingual glands. It should not be confused with sialadenosis (sialosis) which is a non ...

is inflammation of a salivary gland, usually caused by infections, although there are other less common causes of inflammation such as irradiation, allergic reactions or trauma.

Congenital

Congenital disorder A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities ca ...

s of the salivary glands are rare, but may include: *

Aplasia Aplasia (; from Greek ''a'', "not", "no" + ''plasis'', "formation") is a birth defect where an organ or tissue is wholly or largely absent. It is caused by a defect in a developmental process. Aplastic anemia is the failure of the body to produc ...

Atresia Atresia is a condition in which an orifice or passage in the body is (usually abnormally) closed or absent. Examples of atresia include: *Aural atresia, a congenital deformity where the ear canal is underdeveloped. * Biliary atresia, a condition i ...

Ectopic salivary gland tissue Ectopic salivary gland tissue which is located in sites other than the normal location is variously described as aberrant, accessory, ectopic, heterotopic or salivary gland choristoma. Accessory salivary glands An ''accessory salivary gland'' is ...

Stafne defect The Stafne defect (also termed Stafne's idiopathic bone cavity, Stafne bone cavity, Stafne bone cyst (misnomer), lingual mandibular salivary gland depression, lingual mandibular cortical defect, latent bone cyst, or static bone cyst) is a depres ...

- 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 A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

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 The inferior alveolar nerve (IAN) (also the inferior dental nerve) is a branch of the mandibular nerve, which is itself the third branch of the trigeminal nerve. The inferior alveolar nerves supply sensation to the lower teeth. Structure The in ...

canal in the posterior region of the mandible.

Acquired

Dysfunction

Salivary gland dysfunction affects the flow, amount, or quality of saliva produced. A reduced salivation is termed

hyposalivation Xerostomia, also known as dry mouth, is dryness in the mouth, which may be associated with a change in the composition of saliva, or reduced salivary flow, or have no identifiable cause. This symptom is very common and is often seen as a side e ...

. Hyposalivation often results in a dry mouth condition called

, and this can cause

tooth decay Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complicatio ...

due to the loss of the protective properties of saliva. In addition, The results of a study have suggested that hyposalivation could lead to acute respiratory infection. There are two potential reasons for increasing the incidence rate of this infection. First, reduced saliva secretion may impair the oral and airway mucosal surface as a physical barrier, which consequently enhances the adhesion and colonization of viruses. Second, this reduction may also impair the secretion of antimicrobial proteins and peptides. Considering presence of many proteins and peptides with established antiviral properties in saliva, some of which can potentially inhibit virus replication especially coronavirus, it gives the impression that the protective effect of these salivary proteins against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might be the same. Therefore, hyposalivation could be a potential risk factor for acute respiratory infection. It may expose patients at high risk of getting coronavirus disease (COVID-19). However, further investigations are crucial to prove this hypothesis.

Hypersalivation Hypersalivation, or ptyalism, also known as sialorrhea or hypersialosis is the excessive production of saliva. It has also been defined as increased amount of saliva in the mouth, which may also be caused by decreased clearance of saliva.Medscape ...

is the overproduction of saliva and has many causes.

Vascular

* Necrotizing sialometaplasia—a lesion that usually arises from a minor salivary gland on the palate. It is thought to be due to vascular

infarction Infarction is tissue death ( necrosis) due to inadequate blood supply to the affected area. It may be caused by artery blockages, rupture, mechanical compression, or vasoconstriction. The resulting lesion is referred to as an infarct (from th ...

of the salivary gland lobules. It is often mistaken for

oral cancer Oral cancer, also known as mouth cancer, is cancer of the lining of the lips, mouth, or upper throat. In the mouth, it most commonly starts as a painless white patch, that thickens, develops red patches, an ulcer, and continues to grow. When on ...

, but the lesion is not neoplastic.

Infective

Infections involving the salivary glands can be viral or

bacterial Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...

(or rarely

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

). * Mumps is the most common viral sialadenitis. It usually occurs in children, and there is preauricular pain (pain felt in front of the ear), swelling of the parotid,

fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

, chills, and headaches. * Bacterial sialadenitis is usually caused by ascending organisms from the oral cavity. Risk factors include reduced salivary flow rate. * Human immunodeficiency virus-associated salivary gland disease (HIV-SGD).

Traumatic

Oral mucocele Oral mucocele (also mucous extravasation cyst, mucous cyst of the oral mucosa, and mucous retention and extravasation phenomena.) is a condition caused by two related phenomena - mucus extravasation phenomenon and mucous retention cyst. Mucous e ...

— these are common, and are caused by rupture of a salivary gland duct and

mucin Mucins () are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most ...

spillage into the surrounding tissues. Usually, they are caused by trauma. Classically, a mucocele is bluish and fluctuant, and most commonly occurs on the lower lip. * Ranula — the name used when a mucocele occurs in the floor of the mouth (underneath the tongue). Ranulas may grow to a larger size than mucoceles at other sites, and they are usually associated with the sublingual gland, although less commonly they may also arise from the submandibular gland or a minor salivary gland. Uncommonly, a ranula may descend into the neck rather than the mouth (plunging ranula). If small, the ranula may be left alone, but if larger and causing symptoms, excision of the sublingual gland may be indicated. *

Nicotinic stomatitis Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral ner ...

— the hard palate is whitened by

hyperkeratosis Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) ''Robbins & Cotran Pathologi ...

caused by the heat from tobacco use or hot liquid consumption. This irritation also causes inflammation of the duct openings of the minor salivary glands of the palate, and they become dilated. This manifests as red patches or spots on a white background.

Autoimmune

* Sjögren's syndrome * Graft-versus-host disease

Inflammatory

* Post-irradiation sialadenitis *

Sarcoidosis Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly a ...

—there may be

parotitis Parotitis is an inflammation of one or both parotid glands, the major salivary glands located on either side of the face, in humans. The parotid gland is the salivary gland most commonly affected by inflammation. Etymology From Greek παρωτῖ ...

alone or

uveoparotitis Uveoparotitis is a symptom of sarcoidosis. It describes a chronic inflammation of the parotid gland (parotitis) and part of the eye called the uvea (uveitis). There is also a phenomenon called Waldenström's uveoparotitis, where the symptom is re ...

(inflammation of both the parotid and the

uvea The uvea (; Lat. ''uva'', "grape"), also called the ''uveal layer'', ''uveal coat'', ''uveal tract'', ''vascular tunic'' or ''vascular layer'' is the pigmented middle of the three concentric layers that make up an eye. History and etymolog ...

of the eyes), which occurs in

Heerfordt's syndrome Heerfordt syndrome is a rare manifestation of sarcoidosis. The symptoms include inflammation of the eye (uveitis), swelling of the parotid gland, chronic fever, and in some cases, :wikt:palsy, palsy of the facial nerves. Causes The exact cause ...

. *

Cheilitis glandularis Cheilitis is a medical condition characterized by inflammation of the lips. The inflammation may include the perioral skin (the skin around the mouth), the vermilion border, or the labial mucosa. The skin and the vermilion border are more commo ...

—This is inflammation of the minor salivary glands, usually in the lower lip, eversion and swelling of the lip. * Chronic sclerosing sialadenitis is a salivary gland manifestation of

IgG4-related disease IgG4-related disease (IgG4-RD), formerly known as IgG4-related systemic disease, is a chronic inflammatory condition characterized by tissue infiltration with lymphocytes and IgG4-secreting plasma cells, various degrees of fibrosis (scarring) and ...

Neurological

* Frey's syndrome

Neoplastic

* Salivary gland neoplasm File:Relative incidence of parotid tumors.png, Relative incidence of parotid tumors. Updated: Jan 13, 2021
Diagrams by Mikael Häggström, MD File:Relative incidence of submandibular tumors.png, Relative incidence of submandibular tumors.

Diverticulum

A salivary diverticulum (plural ''diverticuli'') is a small pouch or out-pocketing of the duct system of a major

. Such diverticuli typically cause pooling of saliva and recurrent

sialadenitis Sialadenitis (sialoadenitis) is inflammation of salivary glands, usually the major ones, the most common being the parotid gland, followed by submandibular and sublingual glands. It should not be confused with sialadenosis (sialosis) which is a non ...

, especially

. A diverticulum may also cause a sialolith to form. The condition can be diagnosed by sialography. Affected individuals may "milk" the salivary gland to encourage flow of saliva through the duct.

Unknown

Sialolithiasis Sialolithiasis (also termed salivary calculi, or salivary stones) is a crystallopathy where a calcified mass or ''sialolith'' forms within a salivary gland, usually in the duct of the submandibular gland (also termed "Wharton's duct"). Less common ...

- although several possibly coexisting factors have been suggested to be involved in the formation of salivary stones, including altered acidity of saliva, reduced salivary flow rate, abnormal calcium metabolism and abnormalities in the sphincter mechanism of the duct opening, the exact cause in many cases is unknown. * Sialadenosis (sialosis) is an uncommon, non-inflammatory, non-neoplastic, recurrent swelling of the salivary glands. The cause is hypothesized to be abnormalities of neurosecretory control. It may be associated with

alcoholism Alcoholism is, broadly, any drinking of alcohol that results in significant mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognized diagnostic entity. Predomi ...

References

External links

{{Oral pathology *Main