WISDOM TEETH - MYTHS AND FACTS

diagram picture of girl jaws showing arrangement of teeth along with impacted wisdom teeth behind premolar and molar teeth

WISDOM TEETH - MYTHS AND FACTS

SHOULD WE EXTRACT WISDOM TEETH? WHEN AND WHY?
The wisdom teeth or third molars are the farthest teeth in the dental arches and are usually the last teeth to come out… if they come out!

In order for them to erupt normally, there must be sufficient growth in the back of the jaws to accommodate these teeth. In most people who have all of their permanent teeth, this rarely happens and the wisdom teeth cannot erupt.

The growth of the lower jaw occurs mostly towards the back and this growth is essential to allow the eruption of the third molars (circle). If growth is inadequate, the wisdom teeth will remain impacted.

It is very rare to see a person with as many as 32 teeth in the mouth (including wisdom teeth) that are optimally aligned and functionally aligned.

Teeth that have not fully erupted within a normal period of time are called “ impacted ” if they are completely submerged under the gum line and “ semi-impacted ” if they only partially pierce the gum line.

The dental community agrees to recommend the extraction of third molars that are symptomatic or causing problems (pain, infection, damage to other teeth, etc.).

The growth of the lower jaw occurs mostly towards the back and this growth is essential to allow the eruption of the third molars (circle). If growth is inadequate, the wisdom teeth will remain impacted.

It is very rare to see a person with as many as 32 teeth in the mouth (including wisdom teeth) that are optimally aligned and functionally aligned.

Teeth that have not fully erupted within a normal period of time are called “ impacted ” if they are completely submerged under the gum line and “ semi-impacted ” if they only partially pierce the gum line. The dental community agrees to recommend the extraction of third molars that are symptomatic or causing problems (pain, infection, damage to other teeth, etc.).

We can have up to 32 teeth in the mouth including wisdom teeth (*), but it is very rare to see a dentition with all the teeth placed aesthetically and functionally as in this case. (This dentition was treated with orthodontics.)

DO WISDOM TEETH CAUSE OTHER TEETH TO MOVE?

But what about asymptomatic impacted teeth ? Wisdom teeth have historically been blamed for several ailments. They are accused, among other things, of causing tooth displacement by exerting pressure on other teeth when they try to pierce. This would cause the teeth to move and increase tooth overlap and rotations of the anterior teeth over time. Is this “ popular belief ” well founded?

Studies have shown that, although they may play a slight role in these late movements, they are not the main cause and several other more important factors, such as residual growth , must be considered.
Even when the third molars are extracted, it is common to see anterior tooth displacements occur afterwards.
Therefore, several associations of dental professionals have concluded that it is not advisable to extract them only to prevent unwanted tooth displacement.
On the other hand, a semi-impacted tooth or one showing signs of pathology represents a risk of real problems. Such a tooth can be compared to a “time bomb” in the patient's mouth; you never know when they will “explode”!

THERE ARE, HOWEVER, SEVERAL OTHER REASONS FOR HAVING THE THIRD MOLARS EXTRACTED.

For example, if they have symptoms of pain, infection, cavities, difficulty cleaning them, extreme malposition, etc., it is best to have them extracted.
It is almost always indicated to extract a “ semi-impacted ” tooth , because it presents a higher risk of infection and decay in the medium to long term.
In summary, it is frequently indicated to have wisdom teeth extracted that do not come out, but the reason is above all to solve an already present problem affecting these teeth or to avoid the development of pathologies (cysts, tumors, resorption (wear) of the teeth. adjacent teeth).
Extraction is not intended to prevent the movement of other teeth over time.

Although the two lower wisdom teeth of this 24-year-old woman have partially erupted in the mouth, they are covered with gum (semi-impacted) and difficult to clean. They became decayed in just a few months (arrows and dark areas on x-rays indicate decay). It is best to have these third molars extracted before the problem gets worse.

DO YOU WANT TO KEEP YOUR WISDOM TEETH?

If someone prefers to keep their impacted wisdom teeth asymptomatic, these teeth should not be ignored.
It is strongly recommended to have them evaluated regularly (every 3-4 years) using x - rays in order to detect the appearance of the potential problems described above.
Symptoms affecting the third molars may not appear until a very long time after the onset of a problem, and by this time significant irreversible damage is often already present.
Several authors suggest that uninfected and asymptomatic impacted wisdom teeth can remain in the mouth in adults indefinitely. (Zachrisson 2005)

EXTRACT THE THIRD MOLARS AS PART OF AN ORTHODONTIC TREATMENT

Note that it is rare to have to extract third molars as part of an orthodontic treatment. However, this might be necessary if, for example, these teeth prevented the normal eruption of another molar (second molar) or prevented the displacement of teeth towards the back of the mouth ( distalization ). Another exception could be when orthognathic surgery involving mandibular advancement is planned. In such a case, the surgeon will recommend having the lower wisdom teeth extracted at least six months in advance in order to avoid a bad fracture during mandibular surgery.

We like to use the “surprise box” analogy to attempt to describe some unpredictable problems and behaviors with teething. Wisdom teeth lend themselves very well to this comparison; it is difficult to predict if they will come out and if so, how and when. They are full of surprises!

Upper and lower wisdom teeth impacted and resting against the second molars in a 21 year old man. There are even 2 upper wisdom teeth on the right x-ray! These molars will not come out and can damage other teeth.

Impacted wisdom teeth (upper and lower third molars) that grew under the second molars and resorbed their roots to such an extent that the second AND third molars had to be extracted. (courtesy Dr G. Noreau)

Eruption problems of the upper third molars. Only an X-ray can detect this anomaly (25-year-old woman). These teeth will not come out properly and their extreme malposition justifies their extraction. The tooth in the photo on the right can damage the second molar if it stays in the mouth.

A routine x-ray of the 13-year-old patient reveals impacted lower wisdom teeth that are poorly formed but embed on the roots of the second molars, which could damage them in the long term. It would be advisable to have them extracted before their roots are too formed. Note that such a situation may be asymptomatic for the patient.

PREDICTION OF WISDOM TEETH ERUPTION

The main way to assess the presence and position of third molars is to take a panoramic x-ray and assess certain factors such as tooth size, root formation, direction of eruption, available space, jawbones, etc. In order for the wisdom teeth to come out, space is needed behind the dental arches and this requires jaw growth . If the third molars are not too badly positioned, as long as there is growth left, there may be hope that the wisdom teeth will come out but this is far from a “guarantee”.

➡ Find out more about the stopping of jaw growth and the impact this can have on orthodontic and surgical treatments. In an attempt to predict third molar eruption , several methods have been developed, each more ingenious and original than the next, but none has proven to be accurate every time. Some are very simple, while others involve clever calculations of the position of the teeth and the evaluation of future growth.

But… despite the availability of several analytical methods, predicting which teeth will or will not come out is sometimes a matter of chance!

harun M.

Practicing dentistry for 20 years