Wisdom teeth

Wisdom teeth, or third molars, are the teeth that nestle right at the back of the mouth, behind the first and second molars.

Not everyone has them but, if they appear, this usually happens between the ages of 17 and 25, supposedly heralding the person’s growing wisdom. Very often, though, they don’t break through (erupt), instead they become impacted (wedged against bone or existing teeth and unable to fully emerge).


Why does this happen?

Humans today have smaller jaws than our ancestors, allowing for less room in our mouths to accommodate wisdom teeth. It is widely believed this is an evolutionary development in response to changes in our diets to less fibrous foods that require less chewing.

Do impacted wisdom teeth need removing if I have no symptoms?

This is your choice. Opinions vary on whether it is medically justifiable to remove wisdom teeth that are causing no problem. In the US, it is common practice to remove impacted teeth to prevent later problems of overcrowding or infection. The UK’s National Institute for Health and Care Excellence (NICE), on the other hand, claims there is no need to remove impacted wisdom teeth as long as they are not causing a problem. This is backed up by a review of many studies by the highly respected Cochrane Collaboration

  • Looking at wisdom teeth removal to prevent overcrowding, it found the practice was not medically justified.
  • On the extraction of third molars to prevent other problems such as infection, the Collaboration review (Mettes et al 2012) found the data was unclear if this helped or not.

When does impaction become a problem?

If your impacted wisdom teeth cause the following problems, you may need to have them removed:

  • tooth decay that cannot be treated
  • abscesses
  • infection of the gum and connective tissue (pericoronitis and cellulitis)
  • infection of the bone (osteomyelitis)
  • cysts or tumours involving the tooth
  • teeth that obstruct other surgery.

Preventing problems 

To prevent cavities and infection, extra care needs to be taken of wisdom teeth that are not fully erupted. Remember to floss between all of your teeth, and especially between the wisdom tooth and the tooth in front of it. Ensure that your brush reaches all the way to the back when brushing your teeth.

Extracting wisdom teeth

Wisdom tooth removal can be done either in your dentist’s surgery or in an operating theatre by an oral surgeon. The decision depends on the type of anaesthetic being used and the complexity of the procedure.

  • Routine, uncomplicated removal of a single wisdom tooth can usually be done in your dentist’s surgery, using a local anaesthetic.
  • Less routine removal may require the use of a sedative combined with a local anaesthetic. Certain dentists are qualified to undertake this procedure in their surgery.
  • Complicated surgery, or the removal of a number of wisdom teeth, may require a general anaesthetic. This must be done in a fully equipped operating theatre, with an appropriately qualified surgeon, anaesthetist and theatre staff.

What are the risks?

As with any surgical procedure, a measure of swelling, bleeding, bruising and discomfort usually follows wisdom tooth extraction. Some temporary numbness of the tongue, lip or chin may also occur due to nerve injury during the extraction process. If you have a general anaesthetic, there are long-term risks associated with this too. Specific risks of having wisdom teeth removed include:

  • infection of the soft tissue or underlying bone
  • haemorrhage (bleeding)
  • dry socket – a painful condition that occurs more often with tooth extractions in the lower jaw and in people who smoke. With dry socket, no blood clot forms (or it is washed away by rinsing too early) and the normal healing process is prevented.
  • permanent or long-term nerve damage: a small number of people who have wisdom teeth removed can experience long-term (even permanent) loss of sensation in the tongue, lip or chin; this is not common.

How to help the healing

To minimise the risks associated with wisdom teeth removal:

  • Rest up for the first 24 hours - overexerting yourself can put pressure on the surgery site and increase pain and bleeding.
  • Avoid chewing on the site for 24 hours - try switching to a soft diet for a few days.
  • Avoid smoking, which promotes bleeding and slows healing.
  • Avoid alcohol as this can promote postoperative bleeding.
  • Avoid sucking or spitting as this can promote bleeding and dislodge the blood clot, which may lead to dry socket.
  • Control swelling by using an ice pack.
  • Manage any pain with an anti-inflammatory medication such as ibuprofen (not aspirin, which can increase bleeding).
  • After 24 hours, start regular, gentle rinses of the mouth with a warm saline (salt water) solution, if recommended by your dentist.
  • Contact your doctor or dentist if you develop any unusual bleeding, swelling or pain.

New discoveries

Over recent years, it has been discovered that stem cells can be obtained from wisdom teeth, giving us a potential new source of treatments for conditions such as bone disorders and some cancers. In the not-too-distant future we may value our wisdom teeth more highly and think twice before discarding them.

Learn more

Wisdom tooth extraction Mayo Clinic – Mayo Foundation for Medical Education and Research, 2012
Impacted wisdom teeth – do I need them removed? Mayo Clinic – Mayo Foundation for Medical Education and Research, 2014


  1. Surgical removal versus retention for the management of asymptomatic impacted wisdom teeth. Mettes TDIRKG, Ghaeminia H, Nienhuijs MEL, Perry J, van der Sanden WJM, Plasschaert A. – Cochrane Database of Systematic Reviews 2012, Issue 6. Art. No.: CD003879. DOI: 10.1002/14651858.CD003879.pub3.

Credits: Reviewed by W Murray Thomson, Professor of Dental Epidemiology and Public Health, Department of Oral Sciences, Otago University. September 2009. Updated December 2013 by Health Navigator NZ..