Wisdom teeth explained

Wisdom teeth are the third set of molars, and form at the very back of the jaw.

Not all wisdom teeth need to be removed. If your wisdom teeth are through and there is enough space around them to properly clean and floss, there is usually no reason to remove them.

However, if your wisdom teeth are impacted (partially erupted or stuck under the gum) they may cause issues including crowding, decay, and infections.

Here, Santosh Kumar Tadakamadla, a professor in Dentistry and Oral Health at La Trobe University, and Associate Professor Kai Lee, an oral surgeon, share some pearls of wisdom on these unique teeth, including why we have them and when to consider getting them out.

Does everyone have wisdom teeth?

While most people will have four wisdom teeth, some do not have them at all.

Evidence suggests around 22% of people worldwide don’t have wisdom teeth at all, but this varies depending on gender and ethnicity.¹

“Most teeth formation begins in-utero,” says Prof. Tadakamadla. “For wisdom teeth, it’s different. Formation starts happening around 5 years of age, and it requires two types of tissue to come together in the back of the jaw.”

So why don’t some people have them at all? According to Prof. Tadakamadla, there are a number of factors involved:

“There seems to be a hereditary aspect to it. One study² that looked at identical twins found that if one twin did not have wisdom teeth, there was an 80% likelihood their twin didn’t have them either. For non-identical twins, that rate was about 60%.”

“Factors like trauma or exposure to certain drugs, chemicals or environmental factors during development may also play a role.”

Why do we have wisdom teeth?

Wisdom teeth are well-known to cause problems, and many people will have them removed. So, what’s their purpose and why do we have them at all? 

According to Prof. Tadakamadla, most of the evidence points to an evolutionary change in the shape of our jaw.   

“It makes sense if you look at our ancestors and how our physiology and diet has changed: our ancestors used to be more bent over, and they had a much more fibrous diet.” 

“Now, our posture is very upright and the foods we eat are much softer, so it makes sense that our jaws have gotten smaller. However, with a smaller jaw, there is not as much space to accommodate the third set of molars.”

When do wisdom teeth come through? 

Unlike other adult teeth, wisdom teeth arrive much later. Typically, they are fully formed between the ages of 17-25. 

If there is enough space for a wisdom tooth, it will generally come through (erupt) without issues. Where there is less space, a wisdom tooth may only partially erupt, or stay under the gumline. This is referred to as an impacted wisdom tooth. 

Do I have to remove my wisdom teeth? 

Not everyone needs their wisdom teeth out, but Prof. Tadakamadla says it’s important to have regular dental check-ups and speak to your dentist before they become an issue.  

“A panoramic x-ray which takes a picture of the whole mouth can help your dentist to assess how your wisdom teeth are positioned,” says Prof. Tadakamadla.

A/Prof. Lee adds that ideally, you want to remove wisdom teeth before they start causing serious issues:

“It helps to pick up early signs, such as early stages of infection, cysts, tumours, or where a wisdom tooth is pressing against the one next door.”

Other indications you may need your wisdom teeth removed include: 

Inability to clean between teeth 

If there is not enough space to clean the tooth properly, it can become an issue says A/Prof. Lee. “You can't clean your tooth if it's under your gum and you can't reach it with your toothbrush or floss. And if you can't clean your teeth, you can develop gum disease, abscess and infection…. and that's usually a matter of time.” 
 

READ MORE: Everything you need to know about teeth cleaning

Wisdom tooth infections

Signs of a wisdom tooth infection include pain, redness, swelling and pus coming from gum near the wisdom tooth.  

“Around 20-30% of the patients I see are experiencing symptoms of infection,” says A/Prof. Lee. “Ideally, we want to treat any problematic wisdom teeth before it gets to that.” 

Pressure on neighbouring teeth 

A panoramic x-ray can show if wisdom teeth are putting pressure on neighbouring teeth, which can cause crowding and tooth damage. 

“The longer a tooth presses against the one next door, the more chance the adjacent tooth will be damaged,” says A/Prof. Lee. “Pressure can create cracks, crowding and resorption cavities.”

What’s the best age to get your wisdom teeth out? 

If your dentist or oral surgeon has recommended you get your wisdom teeth out, but they are not causing immediate issues, you may be wondering whether you should wait to have them out or not. 

Every case is different, says A/Prof. Lee. However, there are some advantages to getting your wisdom teeth out at a younger age, including quicker recovery and a lower risk of complications.  

“Wisdom teeth are usually fully formed in your 20s. When the teeth are not fully formed, they are not as close to important structures such as nerve or blood vessels or muscle, so you don't have as much risk of damaging the vital adjacent structures.” 
 

READ MORE: Having wisdom teeth out, and how health insurance can help