A mucogingival junction is an anatomical feature found on the intraoral

mucosa 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 ...

. The mucosa of the cheeks and floor of the mouth are freely moveable and fragile, whereas the mucosa around the

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

and on the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

are firm and

keratinized Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up scales, hair, nails, feathers, horns, claws, hooves, and the outer layer of skin in vertebrates. Kera ...

. Where the two tissue types meet is known as a mucogingival junction. There are three mucogingival junctions: on the facial of the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

and on both the facial and lingual of the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. The

palatal The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...

gingiva of the maxilla is continuous with the tissue of the

, which is bound down to the palatal bones. Because the palate is devoid of freely moveable alveolar mucosa, there is no mucogingival junction.Carranza's Clinical Periodontology, W.B. Saunders 2002, page 17.

Clinical importance

The clinical importance of the mucogingival junction is in measuring the width of attached gingiva. Attached gingiva is important because it is bound very tightly to the underlying

alveolar bone The alveolar process () is the portion of bone containing the tooth sockets on the jaw bones (in humans, the maxilla and the mandible). The alveolar process is covered by gums within the mouth, terminating roughly along the line of the mandibu ...

and provides protection to the mucosa during functional use of the structures of the oral cavity during function, such as

chewing Chewing or mastication is the process by which food is crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods. During the mastication proc ...

. Without attached gingiva, the freely moveable alveolar mucosa, being more fragile, would suffer injury during eating and cleansing activities, such as brushing of the

. The width of attached tissue is critical, because the more there is available provides a greater sense of protection against the aforementioned insults to the tissue. Using the mucogingival junction as the boundary demarcating the apical border of the attached gingiva, a

periodontal probe In dentistry, a periodontal probe is a dental instrument which is usually long, thin, and blunted at the end. Its main function is to evaluate the depth of the pockets surrounding a tooth in order to determine the periodontium's overall health. ...

is inserted into the

gingival sulcus In dental anatomy, the gingival sulcus is an area of potential space between a tooth and the surrounding gingiva, gingival tissue and is lined by sulcular epithelium. The depth of the sulcus (Latin for ''groove'') is bounded by two entities: ...

to measure how much of the

gingiva coronal to the mucogingival junction is in fact attached to the underlying bone. The depth of the gingival sulcus, determined by the depth to which the probe enters the sulcus, is not attached to the underlying bone, and is subtracted from the total height of the keratinized tissue. Thus, if the entire height of the keratinized gingiva, from the free gingival margin to the mucogingival junction is 8 mm, and the probing depth on the

tooth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tea ...

at that location is 2 mm, the effective width of attached gingiva is 6 mm. If the probe enters the sulcus and can descend up to or beyond the mucogingival junction, this is called a mucogingival defect.

References

Gingiva {{dentistry-stub