How Much Do You Know About Impacted Wisdom Tooth (Third Molar)?

Posted on Posted in General Oral Health, Oral Surgery

What Is A Wisdom Tooth Or Third Molar?

A wisdom tooth refers to the third molar of each quadrant of the human dentition. It is the most posterior molar of adult dentition. Third molars are generally called wisdom teeth because they erupt so late after other teeth have erupted. Wisdom teeth (third molars) generally erupt at the age of 17 – 25. Most adults have four wisdom teeth but it is possible to have lesser or more than this. When the wisdom teeth are developing, they commonly affect other teeth such as becoming impacted.

Impacted Wisdom Tooth – Photo By Coronation Dental Specialty Group (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons
What Is Tooth Impaction?

Tooth Impaction is defined as a failure of the eruption of a tooth to its normal functioning position in the dental arch within expected period of time. Wisdom teeth are most commonly becoming impacted when they erupt. According to the recent studies, the occurrence rate of impacted third molar among human population is up to 44%. Lower third molar teeth are more commonly involved in impaction as compared to the upper their molar teeth.

What Are The Different Types Of Impacted Wisdom Tooth?

Impaction of wisdom tooth can be classified into several types based on their angulation in relation to the adjacent tooth. The classification is shown as bellow:

  1. Vertical impaction
  2. Horizontal impaction
  3. Mesio-angular impaction
  4. Disto-angular impaction

What Are The Causes Of Tooth Impaction (Especially Third Molar Impaction)?

The causes of tooth impaction can be broadly classified into 2 categories, namely local causes and systemic causes:

  • Local Causes:
    1. Lack of space for the eruption of the teeth (either due to large teeth or small jaw).
    2. Extraction of primary molars at the age of 6-7.
    3. The presence of cyst or tumour.
    4. The presence of scar tissue on the eruption area.
  • Systemic Causes:
    1. Genetic disorders such as amelogenesis imperfecta, cleidocranial dysplasia, and osteopetrosis.
    2. Endocrine disorders such as hypothyroidism, hypoparathyroidism, and hypopituitarism.

What Are The Complications That Can Arise From An Impacted Tooth?

If the impacted tooth is left unattended in the dentition, some complications might arise from the impacted tooth. These possible complications include:

  1. Dental Caries (Due to ineffective cleaning of the impacted tooth)
  2. Periodontal or Gum Diseases.
  3. Formation of Cyst or Tumour.
  4. Pericoronitis /Operculitis (Inflammation of the tissue flap covering the crown of a partially erupted tooth).
  5. Resorption of the root of adjacent tooth.

Pericoronitis – Photo By Coronation Dental Specialty Group (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons
What Are The Indication For The Removal Of Impacted Wisdom Tooth?

There are several conditions which indicate the removal of the impacted wisdom tooth, these conditions include:

  1. Previous history of pericoronitis/ operculitis.
  2. Dental Caries that is unrestorable.
  3. Pulpal diseases that could not be treated.
  4. Periodontal/gum diseases.
  5. Infections such as cellulitis, abscess and osteomyelitis.
  6. Facilitation of the dental treatment plans including orthodontic treatment and provision of dental prosthesis.
  7. Pain that is originated from the third molar.
  8. Fracture of the tooth.
  9. Tooth in the live of bony fracture.
  10. Tooth that impedes oral/dental surgery such as orthographic surgery.

Please be noted that the surgical removal of lower third wisdom tooth is not an absolute indication when it is asymptomatic.

What Are The Contraindications For The Removal Of Impacted Wisdom Tooth?

Removal of impacted wisdom tooth is contraindicated in the following conditions:

  1. When the patients’ medical/dental history shows that the removal of third molars is causing a greater risk for his health.
  2. When there is high risk of damaging adjacent structures (such as dental nerves and the jaw bones) during the removal of the impacted tooth.
  3. When the tooth is expected to erupt fully and serves a functional role in the dentition.
  4. Patients with extreme age.
  5. Patients with compromised medical status.

Most of the time, removal of impacted wisdom tooth involves a surgical procedure called as minor oral surgery. This could be done by either a general dentist or oral surgeon. If you are in doubt, always consult your dentist to figure out the proper treatment plan for your condition.

Article written by,

Dr. Wong Kee Cheong (Tommy)
Dental Surgeon

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