Tooth decay

What is tooth decay?

Tooth decay (also known as dental caries or cavities) is a common diet-related disease that leads to the loss of hard mineral from adult and baby teeth. In its early stages it can appear as a white or dark spot on the tooth, but as more mineral is lost a cavity or hole may appear.

Further mineral loss may lead to the cavity going into the centre of the tooth where the nerve is (the pulp), which may lead to a toothache.

Tooth decay can look like this:

How tooth decay occurs

Millions of bacteria live in your mouth and stick to your teeth in a soft build up called dental plaque. These bacteria use the sugars in the food and drinks you consume to create the energy they need to live.

When turning the sugar to energy, the bacteria in your mouth create acid as a waste product. This acid dissolves the crystals of your teeth and causes mineral loss, weakening the tooth. The more frequently you eat or drink sugary things, the more often the bacteria produce acid and this can lead to signs of tooth decay such as white spots and cavities.

Your saliva works to prevent tooth decay from occurring. It washes sugar out of your mouth and into your stomach, stops acid from causing damage, fights bacteria and can repair the early stages of tooth decay by repairing tooth mineral.

If the amount of acid from the bacteria on your teeth outweighs the protective effect of your saliva, then tooth decay will occur.

Prevention of tooth decay

Tooth decay can be prevented by:

• eating a healthy well balanced diet
  • reduce how often you eat sugary foods or have sugary drinks. Try not to add sugar to your tea or coffee
  • avoid sugary snacks between meals. If you’re going to have something sweet, try to have it at mealtimes
  • drink tap water (containing fluoride) rather than soft drinks or juice; and
  • be conscious of hidden sugars in snacks, cereals and other packaged products.
• brushing your teeth twice a day and flossing once a day – good oral hygiene will reduce the harmful bacteria. Remember that brushing alone will not remove all the bacteria, sugar and acid that have built up between your teeth. If you forget to floss or use an interdental brush (for bigger gaps between teeth), up to a third of each tooth doesn’t get cleaned!
• using toothpaste that contains fluoride and drinking tap water if you’re living in an area with fluoride in the drinking water. Fluoride protects the teeth against acid. If you’re living in an area without fluoridated drinking water, speak to your dentist about what oral care products would be best for you
• chewing sugar-free chewing gum after meals to increase saliva flow – saliva is very important for protecting your teeth from decay
• staying well hydrated as this improves your saliva – remember that dehydration can reduce the amount of saliva you make so drink 6-8 glasses of fluids per day, mostly tap water
• having the deep grooves on some of your teeth sealed with dental material called a fissure sealant, if recommended by your dentist – this can prevent tooth decay on the biting surfaces of your teeth
• not putting any sweet drinks (such as juice, soft drink or cordial) in babies' bottles or toddlers’ sippy cups. Even bottles of milk can cause tooth decay for babies if they get used to sipping on them throughout the night, as the milk sugars continue to wash over their teeth while they sleep
• drinking some tap water to wash sugars out of your mouth if you have sugary food or drinks but can’t brush your teeth soon after
• wiping babies’ teeth with a moist face cloth after their night bottle is best if they are too young to brush.

Saliva helps prevent tooth decay

Saliva is a powerful natural defence against tooth decay. It can wash sugar out of your mouth into the stomach, stop the damaging effect of acid made by bacteria, fight bacteria and reverse the early stages of tooth decay by repairing tooth mineral. A reduced flow of saliva (dry mouth) can increase your risk of tooth decay.

Causes of dry mouth might include:

• Medications – some medicines and drugs can affect your salivary glands and reduce the amount of saliva that they can make, leading to a dry mouth.
• Dehydration – working in a dry environment and not drinking water often enough can lead to a decrease in saliva production. High intake of caffeine found in coffee, tea, chocolate and cola drinks can reduce fluid levels in the body and also reduce saliva.
• Conditions that affect the saliva glands– for example Sjogren's disease.
• Medical treatments – some medical treatments such as radiotherapy, chemotherapy or surgery to the head and neck can permanently reduce saliva flow.

If you have a constant dry mouth, consult your dentist or doctor to find the cause.

Treatment of tooth decay

Early tooth decay is reversible. Saliva can deposit mineral back onto the tooth surface, and improvements in your diet and oral hygiene make a big difference.

Your dentist can treat early areas of tooth decay with fluoride or other products to help with this process. Regular visits to the dentist (every 6 to 12 months) are important so that decay can be identified at this early stage when a filling can be avoided.

X-rays are often needed to diagnose decay as it can occur in areas not visible to the naked eye.

A tooth can appear intact from the outside as shown in this photo:

While decay is visible on an X-ray:

When tooth decay gets worse, a hole may have formed that may need a filling. Your dentist will remove the damaged part of the tooth and repair the tooth with a filling material. It is important to have this done as early as possible as the longer the decay is left untreated, the further it spreads into the tooth. Early detection and treatment help preserve tooth strength and prevent bacteria from damaging its centre.

As decay gets worse, people often experience sensitivity to sweet, cold or hot food and drinks. If you feel this kind of discomfort, speak to your dentist as soon as possible to have the decay treated.

If your tooth has been aching then decay may have reached the centre of the tooth and the nerve inside. When this happens, root canal treatment may be needed to keep the tooth in your mouth.

Your dentist can give you advice about how to prevent tooth decay from occurring again. Just filling a hole will not stop tooth decay from occurring in other areas of the mouth or around the new filling. So, if your dentist has found tooth decay, focus on the things that you can do to prevent further decay in the future.

Learn how to spot tooth decay warning signs.

Where to get help

• Your dentist
• Australian Dental Association ‘Find a Dentist’
• Oral Health Victoria - provides public dental services through the Royal Dental Hospital of Melbourne and community dental clinics, for eligible people.