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 is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ligam ...
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
A third molar, commonly called wisdom tooth, is one of the three molars per quadrant of the human dentition. It is the most posterior of the three. The age at which wisdom teeth come through ( erupt) is variable, but this generally occurs betw ...
(third molars)
are frequently impacted because they are the last teeth to erupt in the oral cavity.
Mandibular
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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
third molars are more commonly impacted than their maxillary counterparts.
Some dentists believe that impacted teeth should be removed
except, in certain cases, canine teeth: canines may just remain buried and give no further problems, thus not requiring surgical intervention.
However, removal of asymptomatic, pathology-free, impacted teeth isn't 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 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 radiography ("diagnostic" and "therapeut ...
. 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 compared with the adjacent second molar gives the basis for this type of classification. This was also given by Pell and Gregory and is called as Pell and Gregory A, B and C classification.
Relationship to occlusal plane Class A-C
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 caus ...
. 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
Gingivitis is a non-destructive disease that causes inflammation of the gums. The most common form of gingivitis, and the most common form of periodontal disease overall, is in response to bacterial biofilms (also called plaque) that is attache ...
around the second molar that is invariably present. Even this minor amount of inflammation can provide
bacteria
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 among ...
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 cau ...
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 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 ...
(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 or ...
microbiota
Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found t ...
. 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 symptoms ...
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, t ...
, 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, commonly called ''lockjaw'' as associated with tetanus, is a condition of limited jaw mobility. It may be caused by spasm of the muscles of mastication or a variety of other causes. Temporary trismus occurs much more frequently than perma ...
(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 separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...
.
When impacted teeth are retained completely within the
alveolar process
The alveolar process () or alveolar bone is the thickened ridge of bone that contains the tooth sockets on the jaw bones (in humans, the maxilla and the mandible). The structures are covered by gums as part of the oral cavity.
The synonymous ter ...
, the associated follicular sac is also retained along with it. Though in most persons the
dental follicle
The dental follicle, also known as dental sac, is made up of mesenchymal cells and fibres surrounding the enamel organ and dental papilla of a developing tooth. It is a vascular fibrous sac containing the developing tooth and its odontogenic organ ...
maintains its original size sometimes it may undergo
cyst
A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which ...
ic degeneration and become a
dentigerous cyst
Dentigerous cyst, also known as follicular cyst is an epithelial-lined developmental cyst formed by accumulation of fluid between the reduced enamel epithelium and crown of an unerupted tooth. It is formed when there is an alteration in the reduc ...
or a
keratocyst A keratocyst is a type of cutaneous cyst. They appear similar to epidermoid cysts; however, are not limited to a specified location on the body. Keratocyst are most often reported in persons with nevoid basal cell carcinoma syndrome
Nevoid basal-ce ...
.
Symptoms
Most commonly the individual complains of food getting lodged beneath the gums and a soreness that is usually confused with throat infections. In slightly milder forms a swelling is visible and mouth opening becomes difficult in severe cases. Pain is invariably present.
Management
Impacted teeth might be extracted or left alone, depending on the dentist (and the health authority's guidelines in that country) and the situation. Extraction might be contraindicated and might be simple or surgical, often depending on the location of the teeth.
In some cases, for aesthetic purposes, a surgeon may wish to expose the canine. This may be achieved through open or closed exposure. Studies show no advantage of one method over another.
Laser can be used to uncover superficially impacted teeth with no bleeding and quick recovery
References
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See also
*
Impacted wisdom teeth
Impacted wisdom teeth is a condition where the third molars (wisdom teeth) are prevented from erupting into the mouth. This can be caused by a physical barrier, such as other teeth, or when the tooth is angled away from a vertical position. Com ...
Dentistry
Acquired tooth pathology