Wisdom Teeth: When They Have to Come Out

Most people meet this question the same way. A dentist looks at an x-ray, says the wisdom teeth should come out, and the patient thinks: but nothing hurts.

That reaction is completely reasonable, and the answer to it is the most useful thing in this article. Whether a wisdom tooth causes pain and whether it causes damage are two separate questions. Plenty of wisdom teeth do the second without ever doing the first.

Why these teeth cause trouble at all

Wisdom teeth, properly called third molars, arrive somewhere between seventeen and twenty five. They are the last teeth to erupt, and they arrive into a jaw that has already finished growing and is already fully occupied.

Human jaws have become smaller over evolutionary time while the number of teeth has stayed the same. For a substantial share of people there is simply not enough room at the back for four more molars. The tooth develops anyway, because the biology has not caught up with the anatomy.

When there is not enough room, the tooth does not stop. It comes in at whatever angle it can, or it stays trapped in the bone. A tooth that cannot fully erupt into a normal position is called impacted.

The angle is the whole story

This is the part that explains why a painless tooth still needs attention.

Vertical impaction. The tooth is upright but has not fully emerged. Often watchable, sometimes fine left alone.

Mesial impaction. The most common type. The tooth is tilted forward, angled toward the tooth in front of it. This is the one that matters most.

Horizontal impaction. The tooth is lying on its side, growing directly into the roots of its neighbour. Almost always needs removal.

Distal impaction. Angled backward, away from the other teeth. Behaviour depends on the degree.

Here is the mechanism worth remembering. A mesially or horizontally impacted wisdom tooth presses against the second molar, the tooth immediately in front of it. That second molar is a fully functional tooth you use every day, and it is worth keeping.

Two things happen at that contact point. The pressure can cause resorption, where the root of the healthy second molar is literally worn away by the tooth pushing against it. And the junction between the two teeth forms a space that is impossible to clean, where decay develops on the back surface of the second molar.

Neither process is painful while it happens. Both are visible on an x-ray. And in the worst cases, the tooth that ends up being lost is not the wisdom tooth at all. It is the healthy molar in front of it.

That is why we look at the angle rather than waiting for symptoms.

The other reason for the timing

There is a straightforward biological argument for removing an impacted wisdom tooth in the late teens or early twenties rather than at forty.

Tooth roots develop gradually. In the late teens, a wisdom tooth root is often only two thirds formed, and the surrounding bone is less dense. The tooth comes out more easily and the healing is faster.

By the mid thirties, the roots are fully formed, sometimes curved, and the bone around them has hardened considerably. The same extraction is a bigger procedure with a longer recovery.

The tooth does not get worse. The removal does.

When we recommend leaving them alone

I want to be clear that not every wisdom tooth needs to come out, and any practice recommending removal of all four as a matter of routine is not really assessing anything.

A wisdom tooth can reasonably stay if it has erupted fully into a normal position, has a tooth to bite against, and you can actually clean it. That last condition is the one people fail most often. A tooth you cannot reach with a brush will eventually develop decay or gum problems, however good its position looks.

If your wisdom teeth are erupted, functional and cleanable, they are teeth. Keep them.

What removal involves

For a straightforward extraction, local anaesthetic, and you are awake. You will feel pressure but not pain. Our practice does not offer sedation, so if your situation calls for it, that is a conversation about referral rather than something we provide.

Recovery for most people is three to five days of swelling and soreness, managed with ice, rest and over the counter pain relief. The instruction that matters most is not rinsing forcefully or using a straw for the first few days. Both can dislodge the clot forming in the socket and lead to a painful condition called dry socket, which is the most common complication and is largely preventable.

More detail on the procedure is on our tooth extractions page.

What to do

If you are in your late teens or twenties and have never had wisdom tooth x-rays taken, that is the entire next step. One image shows the angle, the root development and whether the second molar is being affected.

Ask to see it. The angle is obvious once someone points it out, and you will be able to judge the recommendation for yourself rather than taking it on trust.