Can Wisdom Teeth Cause Tooth Decay?

August 9, 2022
Dr. Joe Xanthopoulos

Many people have their wisdom teeth removed at some point in their adult lives. Oftentimes, wisdom teeth can become painful and bothersome, and given they serve no functional purpose, dentists will typically remove them to eliminate these issues. Just like all of your other adult teeth, wisdom teeth can cause tooth decay. In this guide, we explain how tooth decay progresses and why your wisdom teeth are at a higher risk of rotting.

What Are Wisdom Teeth?

Wisdom teeth are the last adult teeth to ‘erupt’ through the gums. They are also known as third molars.

Most of us have four wisdom teeth that sit at the back of our mouths; two on the upper gum arch and two on the lower gum arch.

Wisdom teeth typically come through between the ages of 17 and 25, long after the rest of our adult teeth have developed.

Some people’s wisdom teeth emerge without any issues and line up perfectly with the rest of their teeth, sitting just behind the second molars.

However, oftentimes our mouths are too crowded for our wisdom teeth to come through normally and they become impacted.

Impacted wisdom teeth may partially emerge, meaning the crown of the tooth is visible, or they may never break through at all.

Because they don’t have enough room to develop properly, impacted wisdom teeth may

  • Grow at an angle towards the second molars
  • Grow at an angle towards the back of the mouth
  • Grow at a right angle to the other teeth (lying ‘flat’ along the gumline)
  • Become trapped within the jawbone

Impacted wisdom teeth can cause a range of issues including cysts, ulcers, damage to other teeth, decay and gum disease.

When impacted wisdom teeth cause pain or complications, they will usually need to be removed.

Symptoms of Wisdom Teeth

Impacted wisdom teeth don’t always cause symptoms, but if they do become infected or begin to damage other teeth, you may experience

  • Red/swollen gums
  • Jaw pain
  • Gums that bleed or secrete pus
  • Bad breath
  • Fever
  • Jaw swelling
  • Unpleasant taste in mouth
  • Difficulty chewing or opening your mouth
  • Sore lymph nodes

What is Tooth Decay?

Tooth decay occurs when the bacteria in our mouths begins to chip away at the layers of our teeth and then infiltrates the gums.

The bacteria living in our mouths creates a film over our teeth. This film is called dental plaque.

When you eat or drink foods containing sugars and carbohydrates, the bacteria within the dental plaque begins to feed on the carbs and sugars for energy. When this process occurs, an acidic substance is formed.

The acidic substance begins to dissolve the tooth enamel, which is the outer surface layer of the tooth.

As the enamel wears down, cavities will start to form. Cavities look like small brown or black pin-pricks that appear on the surface of the tooth. While they may appear tiny and innocuous, they actually open up into much larger holes beneath the tooth’s surface.

When your tooth forms a cavity, this leaves the dentine exposed to bacteria and plaque. The dentine is the soft matter that lies underneath the enamel. Because it’s much softer than tooth enamel, it wears down very quickly once exposed to bacteria.

Once the bacteria has chipped away at the dentine, it can travel to the innermost layer of the tooth called the pulp. The pulp is responsible for giving our teeth sensation and contains nerves and blood vessels.

At this point, you’ll likely feel intense pain in your tooth.

Gum Disease

When the bacteria enters the pulp, you may develop gum disease.

There are two types of gum disease.

The milder form, gingivitis, causes sore and red gums that may bleed.

The more severe form, periodontal disease, can develop if gingivitis goes untreated. Symptoms include gums that bleed or secrete pus, tooth wobbling, pain, and tooth and bone loss.


Bacteria can also cause an infection to develop in the tooth or gum, which is known as an abscess.

A tooth abscess is a pocket that forms at the tip of the tooth root (a periapical abscess) or in the gums beside the tooth root (a periodontal abscess). It contains pus and causes symptoms such as

  • Tooth pain and sensitivity
  • Swollen and sore lymph nodes under the jaw or on the neck
  • A foul taste in the mouth
  • Swollen cheeks
  • Fever
  • A throbbing toothache
  • Headache

This infection can eventually spread to the bone and enter the bloodstream, where it can begin to affect other organs in the body.

The Symptoms of Tooth Decay

If your teeth are decaying, you may experience one or more of the following symptoms

  • Discoloured spots on your teeth
  • Gum pain, bleeding, or pus
  • Cavities
  • Tooth sensitivity
  • Tooth pain
  • Bad breath
  • A foul taste in the mouth
  • Swollen lymph nodes
  • Fever
  • Headache

Tooth Decay and Sepsis

In severe cases where the infection from an abscess has entered the bloodstream, sepsis can occur.

The presence of an infection can cause your immune system to severely overreact. Sepsis is a life-threatening condition.

Symptoms of sepsis include

  • Headache
  • Fatigue
  • Dizziness
  • Fever, sweating or chills
  • Flushing
  • Face swelling
  • Very dark urine
  • Reduced frequency of urination
  • Rapid heart rate
  • Rapid breathing
  • Vomiting
  • Stomach pain

If you notice any of these symptoms, call 000 for immediate medical attention.

Can Wisdom Teeth Cause Tooth Decay?

Yes, wisdom teeth can cause tooth decay.

There are a few reasons why wisdom teeth may be more prone to decay than your other adult teeth.

They can also increase the risk of tooth decay in your surrounding teeth.

Why Do Wisdom Teeth Decay?

Partially impacted wisdom teeth — teeth that have only partly erupted through the gum — are at the highest risk of tooth decay.

Their positioning in the gum lining makes them very hard to effectively clean and floss. It’s common for food to become trapped between the gum and tooth, which can lead to plaque buildup.

As we know, plaque buildup eventually wears away at the tooth and the process of tooth decay begins.

Wisdom teeth can also cause surrounding teeth to decay. When impacted wisdom teeth push against the second molars, the pressure can create irritation and pain.

It also decreases the amount of space between the second and third molars, which makes the area more difficult to clean and more prone to infection.

Can a Wisdom Tooth Get a Cavity?

We know that one of the earliest signs of tooth decay is a cavity.

You can develop a cavity on any of your teeth, including your wisdom teeth.

As mentioned, partially impacted wisdom teeth are more likely to experience cavities and decay than fully erupted teeth as they are challenging to clean.

When you experience a cavity in one of your other adult teeth, your dentist would typically fill the cavity and restore the tooth. They may even perform a root canal if the decay is severe.

The treatment for wisdom teeth cavities, on the other hand, is usually removing the tooth altogether. This is because they do not provide additional functional value and are likely to become reinfected due to their difficult positioning.

However, if your wisdom tooth has fully erupted and isn’t wedged within your gum, your dentist may be able to fill the cavity and restore the tooth as would be done with your other teeth.

Wisdom Teeth: Advanced Decay

If the cavity in your wisdom tooth is left to progress, you are at risk of experiencing advanced decay.

As we know, periodontal disease and abscesses can develop. This can cause damage to the nerves and lead to tooth and bone loss. Gum disease and abscesses can cause infection throughout the body, which can be life-threatening.

Rarely, a benign (non-cancerous) tumour develops, which usually requires the removal of tissue and bone.

woman smiling

Treating Wisdom Teeth Tooth Decay

If your wisdom teeth are causing tooth decay, — either in the impacted or surrounding teeth — it’s important to make an appointment with your dentist as soon as possible.

Your dentist will be able to treat the decay to ensure it does not progress further and create serious health problems. They will also be able to advise whether or not you require a wisdom tooth extraction.

If you are experiencing signs and symptoms sepsis, seek emergency medical attention immediately.

At Kew Dentistry, our dentists can diagnose and treat tooth decay in children and adults. We pride ourselves on our comprehensive approach to dental care.

We understand that dental visits can be a source of anxiety for many people. If you’re feeling concerned about having your dental issues seen to, get in touch with us and we can talk you through your options.