Gingiva

The gingiva, also known as the gums (Latin: gingiva), is a dense and thick mucosa covering the alveolar arches of the maxillae and mandible. It is a part of the digestive system. The gingiva surrounds the teeth and participates in the formation of the oral cavity. It is a mucous membrane that is very tightly bonded to the periosteum of the alveolar arches and necks of the teeth. The primary function of the gingiva is the protection of underlying tissue and teeth.

Visual appearance

The gingiva of a healthy individual has a pink color, although the color can vary in ethnic groups depending on the skin tone and melanin amount of a person. People with darker skin often present with hyperpigmentation of the gingiva, and the intensity of pigmentation can increase with age.

The gingiva is hard and dense in structure, and it reacts to temperature and pressure changes and pain. A healthy characteristic is a textured surface with different-looking dot patterns. This appearance is called the gingival stippling, and it happens due to microscopic elevations and depressions of the underlying connective tissue that projects on the surface of the gums.

Gingiva anatomy

The gingiva begins at the bases of the alveolar arches and ends at the level of the necks of the teeth. The gums can be subdivided into two portions depending on the side of the alveolar arches it covers. The buccal or lip part is the side that faces the cheeks and lips, but the lingual or oral portion is the side that faces the tongue and oral cavity proper.

Together with the dental alveoli of the alveolar arches, periodontal ligament and the cement of the teeth, the gingiva forms a part of the periodontium. The periodontium is the dense connective tissue between the roots of the teeth and the dental alveoli. The gingiva can be classified into three anatomical parts or types - marginal, attached and interdental gingiva.

Marginal gingiva

The marginal gingiva, also called the unattached or free gingiva, is the terminal part of the gums that connects with the teeth and surrounds the necks of the teeth as collars or horseshoe-like endings. This anatomical type is moveable. The site where the marginal gingiva and tooth meets is called the gingival sulcus. It is defined as a space between the margin of the unattached gingiva and the tooth.

The width of the marginal gingiva usually varies between one to two millimeters. Inferior to the mandibular and superior to the maxillary teeth is the free gingival groove. It is a part of the marginal gingiva, and it appears as a linear depression that marks the junction between the marginal gingiva and the attached gingiva. It serves as the border between both anatomical types.

Attached gingiva

The attached gingiva lies between the marginal gingiva and alveolar mucosa. Opposite the marginal gingiva, it is not moveable. Usually, the width of the attached gingiva varies between four to five millimeters. This anatomical type is very dense and firm, stippled and tightly bound to the underlying connective tissues. The junction between the attached gingiva and alveolar mucosa is called the mucogingival line or junction.

Interdental gingiva

The interdental gingiva, also called the interdental papilla, is the anatomical type that fills the space between two adjacent teeth and borders with the gingival sulcus. Usually, healthy gums appear to have a form of a pyramid, and the interdental gingiva is its top part.

The facial papilla is the side of the interdental gingiva facing the oral vestibule, but the lingual papilla faces the oral cavity proper. The col region is the valley-like slight depression that connects the peak of the facial papilla with the peak of the lingual papilla.

Gingiva histology

The gingiva mainly consists of thick and dense connective tissue fibers. The mucosa is covered by the stratified squamous keratinized epithelium. It does not have submucosa, and it also does not contain any glands. The gingiva has a high amount of collagen fibers firmly fused with the periosteum of the alveolar arches. It also contains many sensory nerve endings and is highly vascular.

In the tooth neck area, collagen fibers from the gingiva connect with the collagen fibers from the round ligament of the tooth. It is the only site where the gingival epithelium does not have signs of keratinization. Between the surface of the tooth and gingiva is a physiological space called the gum pocket. In healthy gums, it is very microscopic, but it becomes wider and can be a site of infection during several disorders.

Gingiva functions

The gingiva provides several functions, and they include the following:

• The primary function of the gums is the protection of the teeth and underlying bones. The gingiva works as a barrier to microorganisms and traumas. It is not that easy for harder food particles to injure the gingiva because of its thick and dense structure. With poor gum hygiene and disorders, the teeth are more exposed to various diseases.
• As the gingiva has a close connection with the teeth, it helps to retain the teeth in their place.
• The gums also provide rigidity and anatomical structure invariance during mastication. It evenly distributes the pressure caused by the mastication process.
• As the gingiva contains many sensory nerve endings, it reacts, for example, to temperature or injury.
• And finally, it also has an esthetic function, and the gingiva improves the visual appearance of the structures within the oral cavity.

Neurovascular supply of gingiva

Arterial blood supply

The arterial blood supply for gingiva is provided mainly by the branches of the maxillary artery - a terminal branch of the external carotid artery. The posterior superior alveolar artery supplies the posterior part of the maxillary gingiva, while the anterior superior alveolar arteries provide supply to the anterior and middle aspects of the maxillary gums. The mandibular gingiva receives arterial blood supply from the inferior alveolar artery.

Venous and lymphatic drainage

Venous drainage is provided by the gingival veins that flow into the pterygoid venous plexus. Lymphatic drainage from the buccal aspects of the gingiva is provided by the submental and submandibular lymph nodes. The lingual aspect of the maxillary gingiva is drained via the deep cervical and lateral retropharyngeal lymph nodes. In contrast, the lingual aspect of the mandibular gingiva is drained to the submandibular lymph nodes.

Innervation

The innervation of the gingiva is provided by the maxillary (CN V2) and mandibular (CN V3) divisions of the trigeminal nerve - the fifth cranial nerve. The mandibular gingiva is supplied by the gingival branches arising from the inferior alveolar nerve. Also, the lingual and buccal nerves provide innervation. The maxillary gingiva is mostly innervated by the anterior, middle and posterior superior alveolar nerves that arise from the infraorbital nerve. The nasopalatine and greater palatine nerves also innervate the gingiva of the upper jaw.

Disorders of gingiva

Changes in color, swelling, bleeding, pain sensation, abnormal sensitivity and loss of stippling are only a few indicators of various diseases affecting the gingiva. The best possible prevention for all disorders involving gums includes taking care of oral cavity hygiene and regular dental visits. However, early-stage conditions of gingiva are easy and fast to treat. But untreated diseases can impact overall health, and local infections can spread through the bloodstream to other body parts, affecting the cardiovascular system organs or joints and causing endocarditis or arthritis.

Poor nutrition with a lack of products containing vitamin C can significantly impact overall gum health. As previously described, the gingiva contains many collagen fibers, and vitamin C is needed for their formation. Otherwise, teeth can start to loosen. The most common disorders affecting the gingiva include gingivitis, periodontitis and gingival hyperplasia.

Gingivitis

Gingivitis is the most common disorder affecting the gums, and it often begins without any symptoms. It is characterized as the inflammation of the gingiva causing changes in its appearance. The inflammation occurs due to microorganisms that colonize the gum pockets. Although, it rarely causes gum pocket widening. It presents with mild swelling, redness of the gingiva and gum bleeding.

The best possible prevention is regular and good oral hygiene. Risk factors such as smoking, underlying systemic diseases (diabetes), genetics, aging, stress, hormonal changes, pregnancy, certain medications, an unhealthy diet rich in sweets and fast food and many more to follow can cause gingivitis. However, the most common risk factor is poor oral hygiene.

Periodontitis

Untreated gingivitis can result in a more severe condition - periodontitis. The inflammation from the gingiva can spread to other anatomical structures that form the periodontium and therefore cause its inflammation. The bacterial plaque can spread and grow within the gingival sulcus. It causes the gingiva to become separated from the teeth, forming pathological gum pockets that get infected. If the process continues, the pockets widen and get deeper, and as a result, the inflammation spreads. In the worst cases, the tooth can get loose and infected, resulting in tooth removal.

Gingival hyperplasia

Gingival hyperplasia is a gum enlargement or overgrowth. Usually, it happens around the necks of the teeth. The overgrowth can be very visible in severe cases, and the gingiva can almost completely cover the teeth. Symptoms of this condition include gum swelling, tenderness, pain and red and bleeding gums.

The most common risk factor causing this condition is also poor oral hygiene. Although, gingival hyperplasia can also present as a side effect of certain drugs. And they include immunosuppressants, antiseizure medications and calcium channel blockers that are used to treat several cardiovascular conditions. Usually, once a person stops taking the pills, hyperplasia improves. Certain diseases can present with gingival hyperplasia, including HIV, diabetes and Crohn's disease. The gingiva also can become enlarged during pregnancy.