What is Dental Decay?

Dental caries, or as you more often hear it called ‘dental decay’ is a sugar dependant disease that affects your teeth and root surfaces forming cavities. Dental caries is often shortened to simply ‘caries’- this is the word you are most likely to hear your dentist use.

What Causes Dental Caries?

Bacteria contained in dental plaque feast on sugar in your diet and produce an acid. This acid causes your tooth to start breaking down. This breaking down process or dissolving of your tooth enamel is called ‘demineralization’.

Demineralization is, as the name suggests the process of decreasing the amount of mineral of your tooth. This process will continue through the enamel layer into the dentine and ultimately the bacteria will reach the nerve or pulp of the tooth, unless stopped through improved oral hygiene or by having a filling. If dental caries hits the nerve, or gets close enough that the nerve cannot recover from the insult (irreversible pulpitis), the tooth will need a root canal or to be extracted– and we don’t want that.

Enamel-> dentine-> pulp (nerve)

What happens in our Mouth every time we Eat or Drink something?

Understanding demineralisation and remineralisation?

Normally your mouth, teeth and saliva sit at a neutral pH of about 7. Everybody is happy, teeth are bathing comfortably in saliva, life is good.

You get peckish, indulge on a little sugary snack and the bacteria go wild as this is their favourite food.

As they digest the sugar, they release acid that causes the pH in your mouth to drop (within just 1-2 minutes) and this in turn causes calcium and phosphate (our most important tooth minerals) to be lost from the enamel surface of our teeth.

Bad news!

Luckily we are equipped with our own defence to fight this, in the form of saliva.

This is secreted in generous amounts whenever we eat; it helps us digest food and reverses the demineralization- a process called- “Yes, you’ve guessed it ‘remineralisation’ .

Saliva helps wash away and neutralize the acid, causing the pH to rise over the next 30-40 minutes, on its way back to the neutral resting level; all the time minerals are being added back into our beloved teeth to reform them.

This remineralisation can actually take anything from 20 minutes to two hours to occur depending the factors that affect your Stephan Curve.

So, in your mouth, there exists this ongoing battle between good and evil; between demineralization and remineralisation. Your teeth demineralise then remineralise every time you have anything to eat or drink.

So when does a Dental Cavity form?

If the balance is tipped in favour of demineralization, this means that the tooth is breaking down more than it can be reformed- you will eventually end up with a hole or cavity in your tooth.

How does this happen?

Well, the mouth needs to stay acidic for long periods. This happens when you continuously provide the bacteria with sources of sugar, (by frequently eating or drinking anything with sugary) that can be turned into acid. Saliva never really stands a chance with this repeated bombardment and is unable to fulfil its protective role.

It’s rather like Australia versus New Zealand in rugby league. Let’s assume that Australia are demineralisation (acid- cavity forming) and New Zealand are remineralisation (saliva- cavity protecting)- you will see why I put them this way around shortly.

Most of the time Australia (acid) attack New Zealand (saliva) and New Zealand stop their attempts and push them back over half way. The longer Australia spend in the kiwi half however the more chance they have off overcoming them and scoring a try or creating a cavity.