The oral mucosa is the
mucous membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
lining the inside of the
mouth
In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...
. It comprises
stratified squamous epithelium
A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural i ...
, termed "oral epithelium", and an underlying
connective tissue
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...
termed ''
lamina propria
The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenita ...
''.
The oral cavity has sometimes been described as a mirror that reflects the health of the individual.
Changes indicative of disease are seen as alterations in the oral mucosa lining the mouth, which can reveal systemic conditions, such as
diabetes
Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
or
vitamin deficiency
Vitamin deficiency is the condition of a long-term lack of a vitamin. When caused by not enough vitamin intake it is classified as a ''primary deficiency'', whereas when due to an underlying disorder such as malabsorption it is called a ''seconda ...
, or the local effects of chronic tobacco or alcohol use.
The oral mucosa tends to heal faster and with less scar formation compared to the skin. The underlying mechanism remains unknown, but research suggests that
extracellular vesicles
Extracellular vesicles (EVs) are lipid bilayer-delimited particles that are naturally released from almost all types of cell but, unlike a cell, cannot replicate. EVs range in diameter from near the size of the smallest physically possible unilame ...
might be involved.
Classification
Oral mucosa can be divided into three main categories based on function and
histology
Histology,
also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...
:
*Lining mucosa, nonkeratinized
stratified squamous epithelium
A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural i ...
, found almost everywhere else in the oral cavity, including the:
**Alveolar mucosa, the lining between the buccal and labial mucosae. It is a brighter red, smooth, and shiny with many blood vessels, and is not connected to underlying tissue by
rete pegs
Rete pegs (also known as rete processes or rete ridges) are the epithelial extensions that project into the underlying connective tissue in both skin and mucous membranes.
In the epithelium of the mouth, the attached gingiva exhibit rete pegs, wh ...
.
**Buccal mucosa, the inside lining of the
cheek
The cheeks ( la, buccae) constitute the area of the face below the eyes and between the nose and the left or right ear. "Buccal" means relating to the cheek. In humans, the region is innervated by the buccal nerve. The area between the inside ...
s; part of the lining mucosa.
** Labial mucosa, the inside lining of the lips; part of the lining mucosa.
* Masticatory mucosa,
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
ized
stratified squamous epithelium
A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural i ...
, found on the
dorsum of the
tongue
The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...
,
hard palate
The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans ...
, and attached
gingiva
The gums or gingiva (plural: ''gingivae'') consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.
Structure
The gums are part of the soft tissue lini ...
.
*Specialized mucosa, specifically in the regions of the
taste bud
Taste buds contain the taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as lingual papillae, papillae found on the upper surface of the tongue, soft palate, upper e ...
s on
lingual papillae
Lingual papillae (singular papilla) are small structures on the upper surface of the tongue that give it its characteristic rough texture. The four types of papillae on the human tongue have different structures and are accordingly classified as c ...
on the dorsal surface of the tongue; contains nerve endings for general sensory reception and taste perception.
[University of Michigan Health System, Learning Resource Center at http://histology.med.umich.edu/node/2 ]
Structure
![Oral mucosa](https://upload.wikimedia.org/wikipedia/commons/1/11/Oral_mucosa.png)
Oral mucosa consists of two layers, the surface
stratified squamous epithelium
A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural i ...
and the deeper
lamina propria
The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenita ...
. In keratinized oral mucosa, the epithelium consists of four layers:
*
Stratum basale
The ''stratum basale'' (basal layer, sometimes referred to as ''stratum germinativum'') is the deepest layer of the five layers of the epidermis, the external covering of skin in mammals.
The ''stratum basale'' is a single layer of columnar or ...
(basal layer)
*
Stratum spinosum
The stratum spinosum (or spinous layer/prickle cell layer) is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer is composed of polyhedral keratinocytes. These are joined with desmosomes. Their spiny (Latin ...
(prickle layer)
*
Stratum granulosum
The stratum granulosum (or granular layer) is a thin layer of cells in the epidermis lying above the stratum spinosum and below the stratum corneum (stratum lucidum on the soles and palms).James, William; Berger, Timothy; Elston, Dirk (2005) ''A ...
(granular layer)
*
Stratum corneum
The stratum corneum (Latin for 'horny layer') is the outermost layer of the epidermis. The human stratum corneum comprises several levels of flattened corneocytes that are divided into two layers: the ''stratum disjunctum'' and ''stratum compact ...
(keratinized layer)
In nonkeratinised epithelium, the two deep layers (
basale and
spinosum) remain the same but the outer layers are termed the ''intermediate'' and ''superficial'' layers.
Depending on the region of the mouth, the epithelium may be nonkeratinized or keratinized. Nonkeratinized squamous epithelium covers the
soft palate
The soft palate (also known as the velum, palatal velum, or muscular palate) is, in mammals, the soft tissue constituting the back of the roof of the mouth. The soft palate is part of the palate of the mouth; the other part is the hard palate. ...
, inner lips, inner cheeks, the floor of the mouth, and ventral surface of the tongue. Keratinized squamous epithelium is present in the gingiva and
hard palate
The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans ...
as well as areas of the dorsal surface of the tongue.
Keratinization is the
differentiation of
keratinocyte
Keratinocytes are the primary type of Cell (biology), cell found in the epidermis (skin), epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells.
Basal cells in the stratum basale, basal layer (''str ...
s in the stratum granulosum into nonvital surface cells or squames to form the stratum corneum. The cells terminally differentiate as they migrate to the surface from the stratum basale where the
progenitor cell
A progenitor cell is a Cell (biology), biological cell that can Cellular differentiation, differentiate into a specific cell type. Stem cells and progenitor cells have this ability in common. However, stem cells are less specified than progenitor ...
s are located to the superficial surface.
Unlike keratinized epithelium, nonkeratinized epithelium normally has no superficial layers showing keratinization. Nonkeratinized epithelium may, however, readily transform into a keratinizing type in response to frictional or chemical trauma, in which case it undergoes hyperkeratinization. This change to hyperkeratinization commonly occurs on the usually nonkeratinized buccal mucosa when the
linea alba forms, a white ridge of calloused tissue that extends horizontally at the level where the maxillary and mandibular teeth come together and occlude. Histologically, an excess amount of keratin is noted on the surface of the tissue, and the tissue has all the layers of an orthokeratinized tissue with its granular and keratin layers. In patients who have habits such as clenching or grinding (
bruxism
Bruxism is excessive teeth grinding or jaw clenching. It is an oral parafunctional activity; i.e., it is unrelated to normal function such as eating or talking. Bruxism is a common behavior; reports of prevalence range from 8% to 31% in the gene ...
) their teeth, a larger area of the buccal mucosa than just the linea alba becomes hyperkeratinized. This larger white, rough, raised lesion needs to be recorded so that changes may be made in the dental treatment plan regarding the patient’s parafunctional habits.
Even keratinized tissue can undergo further level of hyperkeratinization; an increase in the amount of keratin is produced as a result of chronic physical trauma to the region. Changes such as hyperkeratinization are reversible if the source of the injury is removed, but it takes time for the keratin to be shed or lost by the tissue. Thus, to check for malignant changes, a baseline
biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
and microscopic study of any whitened tissue may be indicated, especially if in a high-risk cancer category, such with a history of tobacco or alcohol use or are HPV positive. Hyperkeratinized tissue is also associated with the heat from smoking or hot fluids on the hard palate in the form of
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 ...
.
[Illustrated Dental Embryology, Histology, and Anatomy, Bath-Balogh and Fehrenbach, Elsevier, 2011, page 106]
The lamina propria is a fibrous
connective tissue
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...
layer that consists of a network of
type I and
III collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...
and
elastin
Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...
fibers in some regions. The main cells of the lamina propria are the
fibroblasts
A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells o ...
, which are responsible for the production of the fibers as well as the
extracellular matrix
In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide stru ...
.
The
lamina propria
The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenita ...
, like all forms of
connective tissue proper
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...
, has two layers: papillary and dense. The papillary layer is the more superficial layer of the lamina propria. It consists of loose connective tissue within the connective tissue papillae, along with blood vessels and nerve tissue. The tissue has an equal amount of fibers, cells, and intercellular substance. The dense layer is the deeper layer of the lamina propria. It consists of dense connective tissue with a large amount of fibers. Between the papillary layer and the deeper layers of the lamina propria is a capillary plexus, which provides nutrition for the all layers of the mucosa and sends capillaries into the connective tissue papillae.
A
submucosa
The submucosa (or tela submucosa) is a thin layer of tissue (biology), tissue in various organ (anatomy), organs of the gastrointestinal tract, gastrointestinal, respiratory tract, respiratory, and genitourinary system, genitourinary tracts. It i ...
may or may not be present deep in the dense layer of the lamina propria, depending on the region of the oral cavity. If present, the submucosa usually contains loose connective tissue and may also contain
adipose tissue
Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
or
salivary glands
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 gla ...
, as well as overlying bone or muscle within the oral cavity.
The oral mucosa has no muscularis mucosae, and clearly identifying the boundary between it and the underlying tissues is difficult. Typically, regions such as the cheeks, lips, and parts of the hard palate contain
submucosa
The submucosa (or tela submucosa) is a thin layer of tissue (biology), tissue in various organ (anatomy), organs of the gastrointestinal tract, gastrointestinal, respiratory tract, respiratory, and genitourinary system, genitourinary tracts. It i ...
(a layer of loose fatty or glandular connective tissue containing the major blood vessels and nerves supplying the mucosa). The submucosa's composition determines the flexibility of the attachment of oral mucosa to the underlying structures. In regions such as the gingiva and parts of the hard palate, oral mucosa is attached directly to the
periosteum
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones.
Structure ...
of underlying bone, with no intervening
submucosa
The submucosa (or tela submucosa) is a thin layer of tissue (biology), tissue in various organ (anatomy), organs of the gastrointestinal tract, gastrointestinal, respiratory tract, respiratory, and genitourinary system, genitourinary tracts. It i ...
. This arrangement is called a
mucoperiosteum and provides a firm, inelastic attachment.
A variable number of
Fordyce spots
Fordyce spots (also termed Fordyce granules)James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . are visible sebaceous glands that are present in most individuals ...
or granules are scattered throughout the nonkeratinized tissue. These are a normal variant, visible as small, yellowish bumps on the surface of the mucosa. They correspond to deposits of
sebum
A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest nu ...
from misplaced
sebaceous glands
A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number ...
in the submucosa that are usually associated with hair follicles.
A basal lamina (basement membrane without aid of the microscope) is at the interface between the oral epithelium and lamina propria similar to the epidermis and dermis.
Function
Mechanical stress is continuously placed on the oral environment by actions such as eating, drinking and talking. The mouth is also subject to sudden changes in temperature and pH meaning it must be able to adapt to change quickly. The mouth is the only place in the body which provides the sensation of taste. Due to these unique physiological features, the oral mucosa must fulfil a number of distinct functions.
* Protection - One of the main functions of the oral mucosa is to physically protect the underlying tissues from the mechanical forces, microbes and toxins in the mouth. Keratinised masticatory mucosa is tightly bound to the hard palate and gingivae. It accounts for 25% of all oral mucosa. It supports underlying tissues by resisting the loading forces exerted during mastication. Lining mucosa in the cheeks, lips and floor of mouth is mobile to create space when chewing and talking. During mastication, it allows food to move freely around the mouth and physically protects the underlying tissues from trauma. It accounts for 60% of oral mucosa.
* Secretion - Saliva is the primary secretion of the oral mucosa. It has many functions including lubrication, pH buffering and immunity. The lubricating and antimicrobial functions of saliva are maintained mainly by resting; saliva results in a flushing effect and the clearance of oral debris and noxious agents. Saliva contains numerous antimicrobial proteins that help protect the oral ecosystem from infectious agent. The components like lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, and thiocyanate concentrations act as a defense mechanism in the saliva. Saliva is secreted from 3 pairs of major salivary glands (parotid, submandibular, sublingual) alongside many minor salivary glands. It also aids the initial chemical digestion of food as it contains the enzyme amylase, responsible for breaking carbohydrates into sugars.
* Sensation - The oral mucosa is richly innervated, meaning it is a very good at sensing pain, touch, temperature and taste. A number of cranial nerves are involved in sensations in the mouth including trigeminal (V), Facial (VII), glossopharyngeal (IX) and Vagus (X) nerves. The dorsum of the tongue is covered in specialised mucosa. This contains the presence of taste buds allowing taste, and it accounts for around 15% of oral mucosa.
Reflexes such as swallowing, gagging and thirst are also initiated in the mouth.
* Thermal regulation - Although not significant in humans, some animals e.g. dogs rely on panting to regulate their temperature, as sweat glands are only present in their paws
Clinical significance
Infective
Viral
The majority of viral infections affecting the oral cavity are caused by the human Herpes Virus group. Each human herpes virus may present differently within the oral cavity. They are more likely to affect immunocompromised patients such as children and the elderly.
*
Herpetic Gingivostomatitis
Gingivostomatitis is a combination of gingivitis and stomatitis, or an inflammation of the oral mucosa and gingiva. Herpetic gingivostomatitis is often the initial presentation during the first ("primary") herpes simplex infection. It is of greate ...
: A self-limiting viral infection which is caused by Herpes Simplex Virus-1(HSV-1). It usually presents in young children and is very contagious . It is characterised by the presence of small oral blisters which break down and coalesce into ulcers
*
Herpes Labialis
Herpes labialis, commonly known as cold sores or fever blisters, is a type of infection by the herpes simplex virus that affects primarily the lip. Symptoms typically include a burning pain followed by small blisters or sores. The first attack ...
(Cold Sore):Reactivation of latent Herpes Simplex Virus-1 triggered by sunlight, stress, and hormonal changes. It is characterised by the presence of crusting blisters on the upper lip.
*
Chicken Pox
Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV). The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab ...
: A type of viral infection which is caused by Varicella Zoster Virus and presents in children. Numerous itchy blisters are found on the face and body. Blisters could also be found on inner cheek and palate of the mouth.
*
Herpes Zoster/Shingles: Viral infection caused by reactivation of latent Varicella Zoster Virus and found in adults. Patients can present with acute pain before or after the onset of blisters. If viral reactivation occurs in the
facial nerve
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of tas ...
, it can cause
Ramsay-Hunt Syndrome in which patients can develop facial paralysis, blisters around the ears and on the tongue, and loss of tongue sensation.
*
Hand, Foot, and Mouth Disease
Hand, foot, and mouth disease (HFMD) is a common infection caused by a group of enteroviruses. It typically begins with a fever and feeling generally unwell. This is followed a day or two later by flat discolored spots or bumps that may blis ...
: A highly contagious viral infection which infects young children and is caused by Coxsackie Virus A16. It is characterised by presence of small blisters all over the limbs and the mouth.
*
Measles
Measles is a highly contagious infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than , cough, ...
: A highly infectious condition which is caused by Measles virus. It most commonly presents in young children who have not been vaccinated. It is characterised by presence of white spots (
Koplik's Spots
Koplik's spots (also Koplik's sign) are a prodromic viral enanthem of measles manifesting two to three days before the measles rash itself. They are characterized as clustered, white lesions on the buccal mucosa (opposite the lower 1st & 2nd ...
) which rupture to form ulcers on the palate.
*6. Papillomas and warts/ verrucae They are caused by various strains of the Human Papilloma Virus (HPV) of which there are more than 100 strains but usually due to HPV types 6 and 11 (2). Papillomas are mostly spiky, finger like projections, or cauliflower head rounded lobular shaped. Usually painless and singular. Verrucae usually appear on the lips. Verrucae Vulgaris is associated with HPV types 2 and 4. HPV types 16 and 18, designated high risk due to association with cancers, do not present like this in the oral mucosa but as white patches (1). Multifocal Epithelial Hyperplasia (Heck Disease) is rare, usually familial, swellings appear in multiples and are more common to some Native American and Inuit groups. Verricuform Xanthoma, a rare lesion which may resemble papilloma, is often white due to hyperkeratosis, usually appear in 50-70 year age group, commonly on the gingivae. They may be mistaken for papilloma or verrucous leukoplakia but are benign (1).
Bacterial
*
Syphilis
Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, an ...
- Bacterial infection which is usually sexually transmitted. It is caused by bacteria
Treponema Pallidum
''Treponema pallidum'', formerly known as ''Spirochaeta pallida'', is a spirochaete bacterium with various subspecies that cause the diseases syphilis, bejel (also known as endemic syphilis), and yaws. It is transmitted only among humans. It is ...
and it has different types of oral presentation at different stages of the disease.
Fungal
Oral fungal infections are most commonly caused by different Candida species such as
Candida Albicans
''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is us ...
,
Candida Glabrata
''Candida glabrata'' is a species of haploid yeast of the genus ''Candida'', previously known as ''Torulopsis glabrata''. Despite the fact that no sexual life cycle has been documented for this species, ''C. glabrata'' strains of both mating ty ...
and
Candida Tropicalis
''Candida tropicalis'' is a species of yeast in the genus '' Candida''. It is a common pathogen in neutropenic hosts, in whom it may spread through the bloodstream to peripheral organs. For invasive disease, treatments include amphotericin B, ec ...
resulting in oral
Candidiasis
Candidiasis is a fungal infection due to any type of '' Candida'' (a type of yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the mouth ...
.
There are several predisposing factors to fungal infections such as systemic disease for example Diabetes, recent antibiotics, use of steroid inhalers etc . Management includes identifying and addressing contributory factors, the use of topical/systemic anti-fungal agents, oral and denture hygiene instruction.
Different presentations of oral
Candidiasis
Candidiasis is a fungal infection due to any type of '' Candida'' (a type of yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the mouth ...
include:
*
Pseudomembranous Candidiasis
* Erythematous Candidiasis
*
Denture Stomatitis
*
Antibiotic Candidiasis
*
Angular Cheilitis
Angular cheilitis (AC) is inflammation of one or both corners of the mouth. Often the corners are red with skin breakdown and crusting. It can also be itchy or painful. The condition can last for days to years. Angular cheilitis is a type of ch ...
*
Median Rhomboid Glossitis
Median rhomboid glossitis is a condition characterized by an area of redness and loss of lingual papillae on the central dorsum of the tongue, sometimes including lesions of the tongue and palate. It is seen in patients using inhaled steroids a ...
*
Chronic Hyperplastic Candidiasis
*
Chronic Mucocutaneous Candidiasis
Chronic mucocutaneous candidiasis is an immune disorder of T cells. It is characterized by chronic infections with '' Candida'' that are limited to mucosal surfaces, skin, and nails. It can also be associated with other types of infections, such a ...
Autoimmune
*
Lichen Planus
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, fla ...
: A chronic inflammatory disease with different forms of oral presentations. The most classic appearance of
Lichen Planus
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, fla ...
is the presence of white streaks in inner cheek, tongue, and gum.
Desquamative Gingivitis
Desquamative gingivitis is an erythematous (red), desquamatous (shedding) and ulcerated appearance of the gums. It is a descriptive term and can be caused by several different disorders.
Signs and symptoms
Desquamative gingivitis involves lesions ...
can be seen in patients with Lichen Planus. Biopsy is done for definitive diagnosis of
Lichen Planus
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, fla ...
.
*
Graft versus Host Disease
Graft-versus-host disease (GvHD) is a syndrome, characterized by inflammation in different organs. GvHD is commonly associated with bone marrow transplants and stem cell transplants.
White blood cells of the donor's immune system which remain wit ...
: An autoimmune disease developed following bone marrow transplant in which its oral presentation is similar to
Lichen Planus
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, fla ...
*
Pemphigus Vulgaris
Pemphigus vulgaris is a rare chronic blistering skin disease and the most common form of pemphigus. Pemphigus was derived from the Greek word ''pemphix'', meaning blister. It is classified as a type II hypersensitivity reaction in which antibodies ...
:An autoimmune chronic disease with clinical presentation of formation of superficial and large blisters which then burst into ulcers on the skin or mucous membrane.
*
Mucous Membrane Pemphigoid
Mucous membrane pemphigoid is a rare chronic autoimmune subepithelial blistering disease characterized by erosive lesions of the mucous membranes and skin. It is one of the pemphigoid diseases that can result in scarring.
Signs and symptoms
Th ...
: Autoimmune disease which affects only mucous membranes with clinical presentation of hard and rigid blisters which then rupture eventually into deep ulcers.
*
Cutaneous Lupus Erythematosus
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different de ...
: These present as oral discoid lesions which may be present on the inner cheek and behind the lips. White papules may also be present.
Hypersensitivity Reaction
*
Lichenoid Reaction- Intra-oral lesion which shares the appearance of Lichen Planus but arises due to contact hypersensitivity to certain dental materials or drug-induced.
Traumatic
*Frictional Keratosis: This typically presents as white plaques on the oral mucosa due to mechanical trauma. When the cause of frictional keratosis is removed the white patch may resolve
*Hyperplastic reactive lesions or nodular swellings These occur in the oral mucosa due to low grade inflammation or trauma (1, 2). They develop where the mucosa is subjected to chronic minor irritants, mechanical or infective (4). They most frequently occur on the buccal mucosa (inner cheek) along the occlusal line where the teeth meet and the gingivae (the mucosa which covers the gums); reactive nodules occurring here are specifically categorised as epulides instead of polyps. Also the alveolar ridge (the gum where the teeth erupt up from, or if missing, where they used to be) and the hard palate (roof of the mouth) (1). The most common are fibrous nodules called fibroepithelial polyps and epulides (4). Other hyperplastic reactive hyperplastic lesions include those associated with dentures, and papillomas. However, they are all similar in cause and nature, the overproduction of the cells of the mucosa, primarily the epithelial cells, also fibrous myxoid and low inflamed tissue due to irritation (1). 1. Fibroepithelial Polyps are usually pale, firm to touch, and painless but further irritation can cause abrasion and then ulceration or bleeding (1). They are sometimes be called fibroma, such as leaf fibroma, a fibroepithelial polyp often occurring under a denture and appears flattened. However, they are not true benign neoplasms (denoted by suffix ~oma), which are similar in appearance but very rare in the mouth (4). 2. Epulides. The most common epulides are: a) Fibrous Epulis. These are just fibroepithelial polyps located only on the gingivae (5). b) Pyogenic Granuloma and Pregnancy Epulis are both vascular rather than fibrous epulides with more dilated blood vessels making them appear darker pink/ red in colour, and soft (2). They may develop more fibrous as they mature. The Pregnancy variant only appears in pregnancy, usually due to plaque and should resolve with better oral hygiene and at the end of the pregnancy if not (1). Pyogenic Granuloma may occur elsewhere in the mouth such as the tongue and lips (3), but are not therefore epulides. c) Giant Cell Epulis also known as Peripheral Giant Cell Granuloma, are like Fibrous Epulis and occur at the anterior interdental margin, the gum between the teeth at the front (2). They are more common in women. They are often soft round and deep red to purplish blue (1). It is important they are investigated to make are they are not true giant cell granuloma (4). 3. Papilliary Hyperplasia of the palate (1,3), or Epulis Fissaratum/ Denture-induced Hyperplasia (2,5). The cause may be unknown (1) but there is an association with ill-fitting dentures resulting in irritation to the mucosa, usually by overextended flange, and with poor denture or oral hygiene (2,4). Oral thrush can be present but is not thought to be the cause (1)
Idiopathic
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Recurrent Apthous Stomatitis- Recurrent ulceration found in the mouth with a wide variety of predisposing factors. However, the aetiology remains unclear.
There are three forms of RAS: Minor, major, and herpetiform. RAS is usually found in non-smokers and those from high socioeconomic background.
Neoplastic:
● Oral Submucous Fibrosis:
This is a condition that involves inflammation of the tissues under the surface. This may cause rigid tissues and difficulty opening the mouth.
Benign soft tissue neoplasms
1. Peripheral nerve sheath tumours most commonly are traumatic neuromas, a reactive response to trauma (1), neurilemmoma and neurofibroma which are large growing painless tumours usually found on the tongue (3). Neurofibroma may occur as a benign solitary lesion but can present as multiple lesions associated with (Von Reckllinghausen’s Disease) neurofibromatosis (4). They can be preceded by café au lait pigmentation spots on the skin, and as they grow can become very disfiguring (4). Malignant change can occur in neurofibromatosis but very rarely in single lesion presentation. Mucosal neuromas can be associated with other conditions such as Multiple Endocrine Neoplasia (MEN) Syndrome and may precede thyroid cancer. (1, 4)
2. Lipoma and fibrolipoma, are tumour of adipose tissue, or fat, giving them a yellow appearance which varies according to fat content (1, 4). They are usually soft, mobile, slow growing painless and occur mostly in middle age or the elderly.
3. Granular Cell Tumour is also a tumour arising from neural cells, though it was incorrectly thought to arise from muscle cells and therefore previously called Granular Cell Myoblastoma (4), It also is slow growing large painless and occurs mostly in the tongue (1, 3).
4. Congenital Epulis, also known as Congenital Granular Cell Tumour (but not related to Granular Cell Tumour) occur mostly on the upper gum, the maxillary alveolar ridge, of newborns, predominantly females (4). Rarely, they occur elsewhere, usually the tongue. They are usually self-resolving (1).
5. Angiomas – vascular tumours: haemangioma, lymphangioma, venus varix (2). Angiomas are difficult to classify as previously they were considered hamartomas, benign tumour-like malformations (6) but there is debate if they are developmental abnormality, true benign tumour or hamartoma, or can be either (1, 4, 5). Haemangiomas are common in the oral mucosa but can occur in other structures such as salivary glands (4), and can be congenital (from birth) or develop in childhood. Congenital lesions can resolve spontaneously (involute) but those that develop later usually continue to slowly grow. They are usually dark red-purple or blue, soft, sometimes fluctuant (5) and painless. They commonly blanch on pressure. Usually solitary, they can occur as part of syndromes such as Sturge-weber Syndrome affecting the trigeminal nerve. They are at risk of trauma with subsequent excessive bleeding, thrombosis or calcification (2). Lymphangiomas are far less common in the oral mucosa, usually appearing on the tongue, less commonly the lip at birth or in infancy (1, 2, 4). They are colourless to pale pink and may be nodular projections (1) or resemble ‘frog spawn’ domes (2). They can cause macroglossia (enlargement of the tongue) (1, 4). Venous Varix, like varicose vein, usually appear in older people on the lower lip as a blue-purple lump (2).
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Malignant Neoplasms of oral mucosa- Sarcomas
Connective tissue malignancies, sarcomas, are rare in the oral mucosa. Osteosarcoma, chondrosarcoma arise in bone and cartilage, lymphoma in haematological disorders (1). The most common malignancies are carcinomas, overwhelmingly Squamous Cell Carcinoma (SSC) (4). See Oral Cancer.
# Rhabdomyosarcoma are fast growing destructive swellings usually in the maxilla. It is the most common oral sarcoma in children and adolescents (1), but rare (4).
# Kaposi Sarcoma is related to the Kaposi Sarcoma Herpes Virus (KSHV) or Human Herpes Virus (HHV-8) viral infection (3). Predominating on the hard palate and gingivae it develops initially as a macule ranging in colour from red, blue, purple to brown or black, becoming nodular as it grows (2, 3, 4). The lesions are highly vascular and can ulcerate and bleed easily; death is usually from opportunistic infections (1). It is usually associated with HIV /AIDS but also less commonly with immunosuppression such as organ donor recipients or prevalent in some communities such as Mediterranean Jews (1). There is no cure (4) but the lesions respond well to Highly Active Antiretroviral Treatment (HAART) drugs (2)
See also
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Oral mucosa tissue engineering
Tissue engineering of oral mucosa combines cells, materials and engineering to produce a three-dimensional reconstruction of oral mucosa. It is meant to simulate the real anatomical structure and function of oral mucosa. Tissue engineered oral muco ...
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Junctional epithelium
The junctional epithelium (JE) is that epithelium which lies at, and in health also defines, the base of the gingival sulcus. The probing depth of the gingival sulcus is measured by a calibrated periodontal probe. In a healthy-case scenario, the p ...
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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 ...
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Salivary glands
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 gla ...
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Basal lamina
The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane. The ba ...
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Fibroblast
A fibroblast is a type of cell (biology), biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and plays a critical role in wound ...
References
External links
* – "Digestive System: Oral Cavity and Teeth – lip, oral mucosa"
* – "Lip"
* – "Lip"
* Common Dental and Oral Mucosal Disorders, Duke University at https://web.archive.org/web/20160303221658/http://pamodules.mc.duke.edu/Oral_Health/Print.asp?CourseNum=1&LessonNum=3
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Dental anatomy