An impacted tooth is one that fails to erupt into the dental arch within the expected developmental window. Because impacted teeth do not erupt, they are retained throughout the individual's lifetime unless extracted or exposed surgically. Teeth may become impacted because of adjacent teeth, dense overlying bone, excessive

soft tissue Soft tissue connective tissue, connects and surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, Adipose tissue, fat, fibrous tissue, Lymphatic vessel, lymph and blood vessels, fasciae, and synovial membranes.� ...

or a genetic abnormality. Most often, the cause of impaction is inadequate arch length and space in which to erupt. That is the total length of the alveolar arch is smaller than the tooth arch (the combined mesiodistal width of each tooth). The

wisdom teeth The third molar, commonly called wisdom tooth, is the most posterior of the three molars in each quadrant of the human dentition. The age at which wisdom teeth come through ( erupt) is variable, but this generally occurs between late teens a ...

(third molars) are frequently impacted because they are the last teeth to erupt in the oral cavity.

Mandibular 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 ...

third molars are more commonly impacted than their maxillary counterparts. Some dentists believe that impacted teeth should be removed This is often true for third molars causing various problems like pericoronitis, resorption of adjacent second molar etc. Other impacted teeth, especially canines or incisors, can be aligned with the rest of the dental arch by orthodontic treatment, thus regaining and retaining their mechanical and aesthetic function. In some cases, impacted teeth can be let sleeping inside the alveolus, but periodical check-ups are required for a possible pathological development. Removal of asymptomatic, pathology-free, impacted teeth is not a medical consensus: watchful monitoring may be a more prudent and cost-effective strategy and make the future placement of a dental implant through such impacted tooth a feasible approach.

Classification

Classifications enable the

oral surgeon Oral and maxillofacial surgery (OMFS) is a surgical specialty focusing on reconstructive surgery of the face, facial trauma surgery, the mouth, head and neck, and jaws, as well as facial plastic surgery including cleft lip and cleft palate s ...

to determine the difficulty in removal of the impacted tooth. The primary factor determining the difficulty is accessibility, which is determined by adjacent teeth or other structures that impair access or delivery pathway. The majority of classification schemes are based on analysis on a

radiograph Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiography and "therapeu ...

. The most frequently considered factors are discussed below.

Angulation of tooth

Most commonly used classification system with respect to treatment planning. Depending on the angulation the tooth might be classified as: * Mesioangular * Horizontal * Vertical * Distoangular * Palatal * Buccal * Lingual

Relationship of tooth to anterior border of ramus

This type of classification is based on the amount of impacted tooth that is covered with the mandibular ramus. It is known as the Pell and Gregory classification, classes 1, 2, and 3.

Relationship of tooth to occlusal plane

The depth of the impacted tooth in relation to the adjacent second molar serves as the foundation for this type of classification. This was also given by Pell and Gregory and is known as the Pell and Gregory A, B, and C classification. Relationship to the occlusal plane A-C classes

Complications

Erupted teeth that are adjacent to impacted teeth are predisposed to

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main c ...

. Since the most difficult tooth surface to be cleaned is the distal surface of the last tooth, in the presence of an impacted tooth there is always gingival inflammation around the second molar that is invariably present. Even this minor amount of inflammation can provide

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

access to a larger portion of the root surface that results in early formation of

periodontitis Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main c ...

compromising the tooth. Even in situations in which no obvious communication exists between the mouth and the impacted third molar there may be enough communication to initiate

dental caries Tooth decay, also known as caries,The word 'caries' is a mass noun, and is not a plural of 'carie'.'' is the breakdown of teeth due to acids produced by bacteria. The resulting cavities may be a number of different colors, from yellow to black ...

(tooth decay).

Pericoronitis

Pericoronitis is an infection of the soft tissue that covers the crown of an impacted tooth and is usually caused by the normal

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or ora ...

microbiota Microbiota are the range of microorganisms that may be commensal, mutualistic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found ...

. For most people there exists a balance between the host defenses and the oral micriobiota but if the host defenses are compromised like during minor illness such as

influenza Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These sympto ...

or an

upper respiratory tract infection An upper respiratory tract infection (URTI) is an illness caused by an acute infection, which involves the upper respiratory tract, including the nose, sinuses, pharynx, larynx or trachea. This commonly includes nasal obstruction, sore throat ...

, pericoronitis results. Another common cause is entrapment of food beneath the gum flap (also called an operculum). Pericoronitis can present as a mild infection or severe infection. In its mildest form it is just a localized tissue swelling and soreness whereas in severe forms the swelling is slightly larger even sometimes creating

trismus Trismus is a condition of restricted opening of the mouth. The term was initially used in the setting of tetanus. Trismus may be caused by spasm of the muscles of mastication or a variety of other causes. Temporary trismus occurs much more freque ...

(difficulty opening the mouth). Occasionally, an impacted tooth causes sufficient pressure on the roots of adjacent teeth causing it to resorb. An impacted tooth occupies space that is usually filled with bone. This weakens that area of bone and renders the jaw more susceptible to

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

. When impacted teeth are retained completely within the

alveolar process 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 ...

, the associated follicular sac is also retained along with it. Though in most persons the

dental follicle Dental may refer to: * Dental consonant, in phonetics * Dental Records, an independent UK record label * Dentistry, oral medicine * Teeth See also * * Dental care (disambiguation) * Dentist (disambiguation) * Tooth (disambiguation) A tooth (: t ...

maintains its original size sometimes it may undergo

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 bubb ...

ic degeneration and become a

dentigerous cyst A dentigerous cyst, also known as a follicular cyst, is an epithelial-lined developmental cyst formed by accumulation of fluid between the reduced enamel epithelium and the crown of an unerupted tooth. It is formed when there is an alteration in ...

or a keratocyst.

Symptoms

Most commonly, the individual complains of food becoming lodged beneath the gums and soreness, which is frequently misdiagnosed as a throat infection. Swelling is visible in milder forms, and opening the mouth becomes difficult in severe cases. Pain is always present.

Management

Depending on the dentist (and the health authority's guidelines in that country), and the situation, impacted teeth may be extracted or left alone. Extraction may be contraindicated, simple, or surgical, depending on the location of the teeth. Sometimes, a surgeon may wish to expose the canine for aesthetic purposes. This may be achieved through open or closed exposure. Studies show no advantage of one method over another. A laser can be used to uncover superficially impacted teeth with no bleeding and quick recovery.

References

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