Tooth Decay

(Dental Caries)

In this section, we will cover:

1. What is tooth decay?
2. How is it caused?
3. What are the symptoms?
4. How is it diagnosed?
5. How is it treated?
6. How can I prevent it?
7. Foods to avoid

How is it caused? 

Tooth decay is caused by bacteria and sugar. Without either of these, it is impossible for tooth decay to begin. This is why it's so important to brush your teeth well and limit the amount of sugar you have throughout the day! 

Bacteria

• Bacteria is found in "plaque" - a sticky layer which coats our teeth throughout the day
• These bacteria turn sugar in our food into acid which rots the tooth

Sugar (diet)

• The type of sugar and how often you have it affects whether you develop tooth decay and how quickly it spreads
• The more often you eat sugars/carbohydrates, more likely you are to get decay and the faster it will spread
• All carbohydrates have the potential to cause tooth decay
  - Simple refined sugars are worse than complex carbohydrates
  - Chewy treats (like toffee) stick to the teeth so are more likely to cause decay

Important fact: fresh fruit juices/smoothies, dried fruits and fruit yoghurts are extremely likely to cause tooth decay because all of the contained sugars have been released into "free sugars" which act quickly to rot the teeth. Fresh whole fruits can also cause tooth decay but are far less of a concern in comparison.

Other factors which influence the rate of decay include:

1. Tooth surface

• Teeth with deep grooves are harder to clean. This means it's harder to remove the bad bacteria which cause decay
• Teeth with abnormal enamel or dentine. If the enamel or dentine develops abnormally whilst the tooth is still forming under the gum causing "developmental defects" or "dental anomalies". In these conditions, the enamel may chip off easily or be thinner or softer than a healthy tooth. 

2. Fluoride

• Fluoride is a protective agent which helps make the enamel on our teeth stronger
• It replaces the calcium in the enamel with fluoride which makes the enamel more resistant to decay
• It is found in some foods such as milk and salt but it's most effective form is in fluoridated toothpastes and fluoride varnish
• Your dentist can place fluoride varnish on your teeth every 3-6 months to protect them against decay

3. Saliva

• Saliva washes away food/debris to prevent prolonged sugar/acid attack on our teeth
• It contains protective agents, such as calcium and phosphate, which help strengthen our teeth in a process called remineralisation
• Top tip:
  - Saliva flow is reduced when we sleep so it's important not to have sugary treats before bed
  - Sugar-free chewing gum increases the amount of saliva we produce which protects our teeth from decay 

How is it diagnosed?

Diagnosing dental decay consists of:

• Clinical examination
  At every check up appointment, your dentist will carefully dry and assess all the surfaces of your teeth to check for holes or changes in the colour of the enamel. Decay can simply look like white spots or grey/brown discolouration under the surface of the tooth. 
  
  If you have had any pain or symptoms from your teeth, you should let your dentist know as it will help them decide what xrays to take and arrive at the correct diagnosis.  
  

• Xrays (radiographs)
  These are black and white pictures of the teeth which show decay or infection as black shadows within the tooth or around the root.
  
  Xrays are extremely useful to show us how deep the decay has spread into the tooth. They can even show us decay which isn't visible in the mouth (such as decay which has started between the teeth). 
  
  Your dentist will usually take xrays every 6-12 months to check for decay. There are two types of xrays your dentist will consider taking:
  - Bitewings which show the crown of the tooth and help to identify tooth decay
  - Periapicals which show the whole tooth and help to identify infection around the root. 
  

In some cases, for example if you can't tolerate these xrays or if you need a lot of dental work, your dentist will take an orthopantomogram (OPG). This is an xray which rotates around your head whilst you stand still for about 1 minute. It shows up all the teeth in the mouth but is not as good at detecting decay as bitewing or periapical xrays. 

If your dentist is worried about the nerve of the tooth, there are further tests they will carry out. This includes checking the nerve is alive with a cold spray or "electric pulp tester" (EPT). An EPT sends a small shock through the tooth which you should be able to feel as a tingling sensation if the nerve is alive.