The Getting Of Wisdom (Teeth)

Not everyone gets wisdom teeth or have problems with them, and yet they have a terrible reputation for being troublemakers.

We’ll look at the potential problems with wisdom teeth in our next article. But in this one, we’d like to introduce you to your wisdom teeth. You’ll learn about their number, size, shape and location. You’ll also start to discover why it’s important that x-rays are used to monitor your wisdom teeth.

Wisdom Teeth Are Late To The Party

Wisdom teeth are usually the last teeth that will appear in your mouth- that is, if they make an appearance at all. They are the teeth that arrive late to the party, anytime between the ages of 17 and 25. They don’t even start forming in the jaw until about your 4th birthday. The rest of your permanent teeth are already budding inside your jaw at birth.

Every other tooth makes an appearance in the mouth by the time you are 15. Your wisdom teeth arrive fashionably late, sometimes when you are well into your 20s.

How Many Wisdom Teeth Will I Have?

If you have the full set, you’ll have four wisdom teeth. Wisdom teeth are one of the most variable teeth in the mouth, so it’s common to see a variation in number. Some people don’t grow any wisdom teeth, while others may have one, two or three.

Some people manage to grow more than four wisdom teeth! But that’s fortunately a rare thing.

Your dental team may refer to wisdom teeth as ‘third molars’. This is because they are the third molar-type tooth found in each quadrant of your mouth. (Most people will have two incisors, one canine, two premolars and three molars in each quadrant). This adds up to 8 teeth in each quadrant, for a grand total of 32 adult teeth in your mouth).

You may also hear your dentist call wisdom teeth ‘eights’. This refers to the dental numbering system used in Australia. Your central incisors (front teeth) are assigned the number ‘1’ and the third molars are number ‘8’.

The Shape And Size Of Wisdom Teeth

Wisdom teeth are often (but not always)slightly smaller than the nearby molars. We sometimes see ‘diminutive third molars’, meaning they are significantly smaller than their neighbours.

If your other teeth are large, your wisdom teeth are likely to also be large.

Getting To The Root Of The Matter

A first or second molar tooth in the upper jaw will typically have three or four roots.

Lower first and second molars tend to have two strong roots.

The upper and lower wisdom teeth tend to have the same number of or less roots that the neighbouring molars. Very often, the roots of a wisdom tooth are all fused together into a single root. While this sounds like a ‘super-root’, it is often conical in shape. This means, if the tooth needs to come out, it is quite easy to remove.

The shape of the roots of wisdom teeth can vary quite a lot. While some roots fuse together into a cone, others may splay out or curl.

If the wisdom tooth is not causing (or likely to cause) any trouble, the size and shape of the roots don’t really matter. However, if the wisdom tooth needs to be removed, it’s critical that the number, size and shape of the roots is known. That’s one of the reasons why your dentist will want to take an x-ray of your wisdom teeth.

Location, Location, Location

Wisdom teeth, like all teeth, develop and grow deep inside the jaw. Because the wisdom teeth are the last teeth in line, they develop a long way back.

In the upper jaw, wisdom teeth grow near the sinuses in your maxilla. Sometimes the root of an upper wisdom tooth forms part of the wall of the sinus.

In the lower jaw, wisdom teeth grow near the angle of your jaw. Nearby is a bony canal that contains major nerves and blood vessels that runs inside your jaw. Sometimes a lower wisdom tooth grows right next to this canal.

As wisdom teeth erupt into the mouth they usually move away from these vital structures. If the tooth remains embedded (unerupted) in the jaw, it may remain in close proximity to them. If an unerupted tooth needs to be removed, its location relative to these vital structures needs to be known. This is another reason why your dentist will take x-rays of your wisdom teeth.

Wise Up! (Down, and Sideways)

Wisdom Teeth are notorious for trying to barge their way into the mouth on an angle. Most of the other teeth come through fairly straight (although some need braces to achieve good alignment). Wisdom teeth often seem to do somersaults in the jawbone* before coming in crooked.

(*Wisdom teeth can’t actually do somersaults. But we’ve seen them try to come through at all kinds of crazy angles)

Sometimes the angle that the wisdom tooth is on means that it can’t fully erupt into the mouth. Dentists call this ‘impaction’.

If the tooth remains below the gumline, it is said to be ‘unerupted’.

Impactions of wisdom teeth can be mild or severe. The teeth might poke through the gum to some extent (partially erupted), or stay completely submerged. They can end up lying horizontal in the bone, or butt up tight against the tooth in front. Sometimes they look like they completely lost the plot and end up heading deeper into the jaw, away from the rest of the teeth.

(Some wisdom teeth would not make good Scouts!)

If your wisdom tooth has decided to follow an angled trajectory, your dentist will want to know. Once again, this important information is only available to your dentist from an x-ray.

So Now You Know…

• that wisdom teeth are one of the mouth’s most variable tooth in terms of number, size, shape and position
• that wisdom teeth are sometimes located near vital structures like sinuses, nerves and blood vessels
• that your dentist will want to use x-rays to find out important information about the growth of your wisdom teeth

In our next article, you’ll discover why wisdom teeth have a reputation for causing trouble.

First Published November 9, 2015 – Updated in June 2019