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Tooth decay Dr Manasi Bhansali Reviewed by Dr Manasi Bhansali, Dentist

Tooth decay can wear down your pearly whites and cause a variety of dental problems. Understand the causes and how to lower your risk.

If any of your teeth feel painful or sensitive when you eat and drink, or you see white, brown or black spots on the tooth's surface, these might be signs of tooth decay.

Tooth decay (dental caries) can affect people of all ages, including young children. Untreated tooth decay can cause serious dental health issues and even impact your overall health, so it’s important to understand what it is and how to lower your risk. 

What is tooth decay? What causes it?

Tooth decay is the damage that happens to the surface of your teeth if plaque accumulates for long enough. Plaque is a bacteria-filled film that can build up on your teeth. Those bacteria feed on things like sugar and carbohydrates, releasing corrosive acids while they do it. The acid is what can start dissolving and damaging your tooth’s outer layer (the enamel).

When decay sets in, it may start to appear as little spots on the surface of your teeth, but these aren’t usually visible to the naked eye. A dentist or other healthcare professional might need to use special tools to spot this stage of decay. 

If left untreated, the acid can damage the enamel badly enough to create a hole (a cavity).

Grandparents Holding Child

Are tooth decay and cavities the same thing?

No. Tooth decay can cause cavities, but they aren’t the same thing. Tooth decay is the damage caused by the acid released by bacteria in plaque, while a cavity is one possible end result of that damage. 

It’s possible for a tooth to have decay without a cavity forming. 

What cavities look like

Unfortunately, you can’t usually see cavities or early stages of tooth decay with the naked eye. That's why it's important to have regular dental check-ups so that a dentist or hygienist can look out for signs of tooth decay in you or your child. 

However, they usually begin with white stains near the bottom of the tooth, close to the gum. If tooth decay isn't treated, these stains can turn yellow-brown or black and you might experience other symptoms of tooth decay as the tooth continues to wear down. 

Symptoms of tooth decay

While you can’t always see the effects of tooth decay, there are occasionally symptoms that are noticeable in other ways. These include:

Can cavities go away?

Cavities don't go away by themselves. If tooth decay isn't treated, the tooth can wear down to the soft centre (the pulp). This contains nerve endings and may cause pain or sensitivity.

A tooth that's severely damaged by decay can break apart. If bacteria reach the gums, this can lead to gum disease or a dental abscess which also needs to be treated by a dentist.

Solutions for cavities

When you make an appointment with your dentist, they'll typically examine your mouth and use dental x-rays to look for any signs of tooth decay. If they spot decay or cavities, they'll discuss treatment options with you. The right treatment will depend on the severity of decay.

  • A fluoride application and improvements to your oral hygiene may be a solution for mild tooth decay.
  • A dentist might use a filling or crown to address a cavity.
  • If the cavity has reached the centre of the tooth, you may need root canal treatment to remove the infection.
  • If your tooth is too badly damaged to repair, the only option may be an extraction to prevent the decay from affecting your other teeth.

How common is tooth decay?

According to oral health surveys, tooth decay is common in Australia, especially among children and teenagers.1,2

  • 42% of Australian children aged 5–10 have experienced decay in their primary (baby) teeth.
  • 24% of Australian children aged 6–14 have experienced tooth decay in their permanent (adult) teeth.
  • More than a quarter of Australian children and adults have at least one tooth with untreated tooth decay.

Tooth decay affects plenty of New Zealanders, too. Again, it’s especially common among children.3

The good news is that there are ways to lower your risk and your family’s risk of developing tooth decay.

How to lower your risk of tooth decay

You can lower your chances of developing tooth decay and cavities by taking good care of your teeth. This mostly involves a combination of at-home behaviour and regular dental visits.

  • brushing your teeth twice a day using fluoride toothpaste
  • flossing once a day to clean the surfaces between your teeth
  • cutting down on sugary food and drinks, especially between meals
  • drinking plenty of water to rinse your mouth of bacteria (especially tap water containing fluoride)
  • visiting your dentist for regular check-ups as often as they recommend.

Children's teeth tend to be more prone to cavities because they're softer and thinner. A dentist may recommend fissure sealants as a preventive measure to help protect their teeth against decay.

It’s important to note that sometimes tooth decay can happen even if you try your best to maintain good oral hygiene and regular dental check-ups. Certain health factors can heighten your risks of decay. A dentist may recommend certain preventive measures, such as more frequent professional cleaning, specialised hygiene products, or changes to your lifestyle.  

Questions about your dental health? Consider speaking to a professional.

Search for a dental clinic near you. Their Dental Care Network listing will help you learn about their dentists, services, opening hours and more.

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1 Do LG & Spencer AJ (Editors) 2016. Oral health of Australian children: the National Child Oral Health Study 2012–14. Adelaide: University of Adelaide Press.

2 Slade GD, Spencer AJ, Roberts-Thomson KF (Editors) 2007. Australia’s dental generations: the National Survey of Adult Oral Health 2004–06. Dental Statistics and Research series no. 34. AIHW cat. no. DEN 165. Canberra: AIHW.

3 Aung YM Sandar T Jelleyman T et al. Dental caries and previous hospitalisations among preschool children: findings from a population-based study in New Zealand. The New Zealand Medical Journal. 2019; 132(1493): 44-53.

The purpose of this article is to promote better understanding of dental health topics. It’s not meant to replace professional advice or diagnosis. Always talk to a dentist, doctor or other qualified healthcare professional if you have a question about dental or medical conditions.

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