Wisdom teeth or third molars (wisdom molars) are the teeth farthest away in the dental arches and they are usually the last ones to erupt if they ever come out! There are four wisdom molars, 2 in the upper jaw (one on each side) and 2 in the lower jaw (one on each side). For their eruption to occur normally, there must be sufficient growth at the back of the jaws to accommodate these teeth. 

In most people, all the wisdom teeth (all the 4) fail to erupt completely. The growth of the lower jaw occurs mostly at the back and this growth is essential to allow the eruption of the third molars. If growth is inadequate, wisdom teeth remain impacted (unerupted). It is very rare to see someone with the maximum possible of 32 teeth in the mouth (including wisdom teeth) that are optimally aligned and functional.

How was the name Wisdom teeth given to the 3rd molars?

The 3rd molars usually erupt when an individual has crossed adolescence and becomes a young adult that is between 18-25 years. Due to the age at which they erupt, these teeth have been called the wisdom molars or wisdom teeth. Wisdom is a misnomer and their eruption is not associated with wisdom. 

In our ancestors, these wisdom molars were functional as the size of the dental arches or jaw bones were bigger. With evolution, the sizes of the jaw bones have diminished resulting in impacted (not erupted) or incompletely erupted or malaligned wisdom molars. Thus, the wisdom molars do not participate in the chewing or masticatory function as the other teeth do. Therefore, they are now classified as vestigial organs like the appendix. 

Problems associated with Wisdom molars-

  1. Wisdom molars can completely erupt, semi-impacted (partially erupted) and completely impacted (non-erupted but in jaw bone). Completely erupted wisdom molars may often (lower jaw) be covered by a portion of gum tissue called operculum, under which food debris accumulate and lead to inflammation called pericoronitis. Pericoronitis can lead to severe pain, difficulty in mouth opening, chewing and acute symptoms like lymph node enlargement and fever may also occur. 
  2. Fully erupted wisdom molars may be malpositioned. Usually, the upper wisdom molars erupt towards the cheek and often cause irritation of the cheek mucosa. 
  3. Semi-impacted wisdom molars- common for the lower wisdom molars, these teeth begin to erupt but fail to erupt completely due to lack of space. These teeth can be angulated so that some part of the tooth crown is visible in the mouth and the rest under the gums. Semi-impacted wisdom molars are difficult to clean and maintain, resulting in decay. As these decay, they cause the adjacent 2nd molars also to decay. 
  4. Impacted wisdom molars- these fail to erupt into the mouth. These teeth are not visible in the mouth at all but are present in the jaw bone. They can give rise to pain when actively erupting but lack of space limits their eruption. These teeth have also been referred to as "Time-Bombs" as they can result in cysts, tumours or resorb (eat away) 2nd molar tooth roots. 
  5. Wisdom molars are also blamed for the relapse of already treated dental crowding during adolescence, but it is a matter of controversy. 
  6. Wisdom teeth may have variable shapes- These can be multi-rooted like other molars or have joint roots, angulated roots or conical single roots or can have a tiny crown (peg shaped). 

Reasons for removing wisdom molars- 

  • If symptoms, such as pain, infection, decay and difficult to clean or severe malposition is present, it is best to remove them.
  • It is almost always indicated to extract a semi-impacted wisdom molar because it presents a higher risk of infection and decay in the long term. 
  • In summary, it is frequently indicated to extract wisdom teeth that do not come out, but the reason is mainly to prevent damage of adjacent 2nd molar (resorption) or development of pathologies (cysts, tumours). 

Reasons for retaining a wisdom molar- 

  • If the tooth is well-positioned, fully erupted and has an antagonist (opposing tooth in the opposing arch), there is no need to extract. 
  • If the gum flap covering the tooth has been removed and the tooth is maintainable by regular brushing, it can be retained.
  • 3rd molars are often retained when the teeth ahead of them in the arch are missing and a fixed artificial tooth prosthesis has to be placed. 

How to prevent wisdom tooth problems? 

Wisdom teeth problems are inevitable. But, the problems can be minimized by predicting their eruption using a panoramic radiograph and evaluating certain factors, such as the size of the teeth, the formation of their roots, the direction of the eruption, the available space, the jaw bone, etc. 

Wisdom tooth removal

It is often believed that wisdom tooth removal is very painful and leads to a lot of swelling. Wisdom teeth are surrounded by dense bone and hence, pose a difficulty during removal as opposing to other teeth. Also, their closeness to the mandibular canal may lead to certain complications. Hence, wisdom molar removal is performed by trained oral surgeons. Routinely, a minor surgical procedure is required to removed semi-impacted and impacted 3rd molars. The dense bone surrounding the 3rd molars is slightly trimmed and the tooth may be sectioned and removed in 2-3 separate parts to conserve surrounding bone and prevent nerve damage. Some swelling does occur post removal, but nowadays good medications are available to tackle it. 

To conclude, "it is not always wise to retain wisdom teeth" and "removal of these teeth will not affect the wisdom". 

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Different angulations of impacted wisdom teeth
Different complications due to wisdom teeth