Classification and Diagnosis
- Teeth are classified as developing, erupted, embedded, or impacted.
- Wisdom teeth are the most likely to become impacted.
- Impacted wisdom teeth develop between the ages of 14 and 25.
- Impacted wisdom teeth can be classified by direction, depth, available space for eruption, and the amount of soft tissue or bone covering them.
- Classification helps estimate the risks and complications associated with wisdom teeth removal.
- Impaction can be diagnosed clinically by assessing the angulation, depth, and eruption potential.
- Panoramic radiographs or cone-beam CT scans are used to diagnose impaction when the tooth cannot be assessed clinically.
- Predictors for impacted wisdom teeth include the ratio of space between the tooth crown length and available space, and the angle of the teeth compared to other teeth.
- The ratio of space available to the length of the crown of the tooth is a reliable predictor of impaction.
- Screening at a younger age may be necessary if the second molars fail to erupt.
- Radiographs can be avoided if the majority of the tooth is visible in the mouth.
Signs, Symptoms, and Causes
- Impacted wisdom teeth without communication to the mouth rarely have symptoms.
- Impacted wisdom teeth that communicate with the mouth can cause pain, swelling, and bleeding.
- Low-grade chronic periodontitis can occur on impacted wisdom teeth or the second molar.
- Asymptomatic wisdom teeth can still be infected for many years before symptoms develop.
- Symptoms of impacted wisdom teeth can include bad breath and bleeding from the gums.
- Wisdom teeth become impacted when there is not enough room in the jaws for them to erupt.
- Genetic predisposition plays a role in tooth impaction.
- Jaw and tooth size, as well as tooth eruption potential, are influenced by genetics.
- Some believe that a decrease in jaw size is due to modern diets that are softer and less coarse.
- Insufficient room in the jaws leads to the wisdom teeth becoming impacted.
Complications and Treatment
- Cysts or tumors can develop over time around impacted teeth.
- Estimates suggest that the incidence of cysts or neoplasms around impacted teeth is around 3%, mostly seen in people under 40.
- Pericoronitis, or infection of the gum tissue over the impacted tooth, is the most common pathology in partially impacted teeth in individuals over 20 years old.
- Bacteria associated with infections include Peptostreptococcus, Fusobacterium, and Bacteroides.
- Cavities on the wisdom tooth or adjacent second molar occur in 15% of people with retained wisdom teeth exposed to the mouth.
- Roughly 25% of patients with retained, asymptomatic wisdom teeth have gum infections (periodontal disease).
- Teeth with periodontal pockets greater than 5mm have tooth loss rates starting at 10 teeth lost per 1000 teeth per year.
- Wisdom teeth removal is the most common treatment for impacted wisdom teeth.
- The procedure can be simple or surgical, depending on the depth of impaction and angle of the tooth.
- Pericoronitis can be treated with local cleaning, antiseptic rinse, and antibiotics if severe.
Historical Context and Medical Considerations
- Wisdom teeth have been mentioned in ancient texts and works of philosophers, scientists, and dentists throughout history.
- The management of impacted wisdom teeth became more routine with the development of sterile technique, radiology, and anesthesia.
- Plato, Hippocrates, Darwin, and early manuals of operative dentistry discussed wisdom teeth.
- The late 19th and early 20th centuries saw advancements that allowed for the easier management of impacted wisdom teeth.
- The understanding and treatment of impacted wisdom teeth have evolved over time.
- ICD-10 Diagnosis Code K01.1 is used for impacted teeth.
- NICE provides guidance on the extraction of wisdom teeth.
- Impacted wisdom teeth can cause complications like nerve injury and jaw fracture.
- Wisdom teeth can lead to crowding of other teeth.
- Mandibular third molar impaction is classified in the literature.
- John Tomes' 1873 text describes techniques for removal of wisdom teeth.
- Techniques include descriptions of nerve injury, jaw fracture, and pupil dilation.
- Other texts from the late 19th and early 20th centuries discuss de-evolution of wisdom teeth.
- Evolution of surgical techniques for wisdom teeth removal.
Prognosis, Epidemiology, and Controversies
- Risk of cyst or neoplasm forming in tissues around the tooth.
- Chance of disease or symptoms increases with age.
- 30% - 60% of people with previously asymptomatic impacted wisdom teeth will have them extracted due to symptoms or disease.
- Extraction improves periodontal status of the second molar.
- Benefit diminishes beyond the age of 25.
- Missing third molars (excluding wisdom teeth) occur in 9-30% of populations.
- Eruption rate of wisdom teeth in maxilla and mandible.
- Frequency of impacted lower third molars in a Swedish study.
- Frequency of retained impacted wisdom teeth without disease and symptoms.
- Incidence of wisdom tooth removal in England and Wales.
- Prophylactic extraction of third molars debated.
- Surveillance as a management strategy for retained wisdom teeth.
- Trigeminal nerve injuries following third molar removal.
- Recommendations from organizations like NICE and American Public Health Association.
- Coronectomy as an alternative management option for 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. Completely unerupted wisdom teeth usually result in no symptoms, although they can sometimes develop cysts or neoplasms. Partially erupted wisdom teeth or wisdom teeth that are not erupted but are exposed to oral bacteria through deep periodontal pocket, can develop cavities or pericoronitis. Removal of impacted wisdom teeth is advised for the future prevention of or in the current presence of certain pathologies, such as caries (dental decay), periodontal disease or cysts. Prophylactic (preventative) extraction of wisdom teeth is preferred to be done at a younger age (middle to late teenage years) to take advantage of incomplete root development, which is associated with an easier surgical procedure and less probability of complications.
| Impacted wisdom teeth | |
|---|---|
| Other names | Impacted third molars |
 | |
| 3D CT of an impacted wisdom tooth adjacent the inferior alveolar nerve prior to removal of wisdom tooth | |
| Specialty | Dentistry, oral and maxillofacial surgery |
| Symptoms | Localized pain and swelling behind the last teeth |
| Complications | Infections, loss of adjacent teeth, cysts |
| Usual onset | Late teens, early 20s |
| Types | Full vs partially impacted, direction of impaction |
| Causes | Congenital |
| Diagnostic method | Examination, x-ray |
| Differential diagnosis | Other causes for dental pain, TMJ pain |
| Treatment | Good dental care, removal of wisdom teeth |
| Frequency | 70-75% of the population |
Impacted wisdom teeth are classified by their direction of impaction, their depth compared to the biting surface of adjacent teeth and the amount of the tooth's crown that extends through gum tissue or bone. Impacted wisdom teeth can also be classified by the presence or absence of symptoms and disease. Screening for the presence of wisdom teeth often begins in late adolescence when a partially developed tooth may become impacted. Screening commonly includes a clinical examination as well as x-rays such as panoramic radiographs.
Infection resulting from impacted wisdom teeth can be initially treated with antibiotics, local debridement or surgical removal of the gum overlying the tooth. Over time, most of these treatments tend to fail and patients develop recurrent symptoms. The most common treatment for recurrent pericoronitis is wisdom tooth removal. The risks of wisdom tooth removal are roughly proportional to the difficulty of the extraction. Sometimes, when there is a high risk to the inferior alveolar nerve, only the crown of the tooth will be removed (intentionally leaving the roots) in a procedure called a coronectomy. The long-term risk of coronectomy is that chronic infection can persist from the tooth remnants. The prognosis for the second molar is good following the wisdom teeth removal with the likelihood of bone loss after surgery increased when the extractions are completed in people who are 25 years of age or older. A treatment controversy exists about the need for and timing of the removal of disease-free impacted wisdom teeth. Supporters of early removal cite the increasing risks for extraction over time and the costs of monitoring the wisdom teeth. Supporters for retaining wisdom teeth cite the risk and cost of unnecessary surgery.
The condition can be common, with up to 72% of the Swedish population affected. Wisdom teeth have been described in the ancient texts of Plato and Hippocrates, the works of Darwin and in the earliest manuals of operative dentistry. It was the meeting of sterile technique, radiology, and anesthesia in the late 19th and early 20th centuries that allowed the more routine management of impacted wisdom teeth.
