The five stages of Tooth Decay

There are five stages of tooth decay and if a sudden toothache has you thinking about a trip to the dentist, you may be at one of the later phases. 

This post explains what causes tooth decay, how to identify the five stages and how your dentist might treat your sore tooth.

Firstly: What is tooth decay?

Put simply, tooth decay is what happens when an infection takes hold inside your tooth. 

This happens when the tooth’s surface is weakened enough for a hole to develop, allowing bacteria to break through your enamel - the tough outer layer of your teeth - and enter the inner layers, the dentine and the pulp (more on those later). 

These holes are known as cavities. 

What causes cavities?

Cavities are caused by plaque; a soft, sticky film that builds up on the tooth’s surface. Plaque contains millions of bacteria. These bacteria produce acid, which destroys the enamel over time if food and drink residue is not cleared away quickly enough by brushing and flossing. 

Some medical conditions and medications contribute to tooth decay, and even excessive consumption of bottled water that doesn’t contain fluoride can increase the risk. 

But far and away the greatest culprit is a diet high in sugar and carbohydrates. The bacteria in plaque thrive on starchy and sweet foods like soft drinks, cakes and sweets and even fruit juice and dried fruit. The starchier and sweeter the food, the more acid the bacteria produce, and the faster your tooth’s protective coating gets worn away. 

Regular brushing and flossing are the key: if you don’t allow plaque to build up, bacteria won’t have a chance to weaken your enamel and cause cavities.

Enamel: the outer armour

Enamel is extremely hard, but it is not invincible, especially in areas where plaque accumulates like the crevices on top of your teeth and the gaps in between them.

When plaque is allowed to build up in those areas over time, the enamel becomes weak. 

Preventing tooth decay

The good news is that it’s really easy to prevent the build-up that causes cavities. 

The two most reliable, tried-and-true methods to do this are:

  • Brushing and flossing twice daily
  • Limiting your intake of sugary and starchy foods. 

Even though it is that easy to prevent, tooth decay is a very common problem that affects young and old.

Nearly half of all children under six years of age have tooth decay. A recent Australian study found at least one in 10 children have an adult tooth with untreated decay.

On average, Australians aged 15 years and up will have around eight fillings as a result of tooth decay.

Understanding tooth decay

To understand the stages of tooth decay, let’s look at the different layers of the tooth that it can affect. 

Teeth have three layers: enamel, dentine and pulp.

Enamel is the outer layer of the tooth. It is the white coating you see, and it is the hardest substance in the human body.  Its job is to protect the soft, sensitive inside of the tooth.

Dentine is a yellow-coloured layer that sits beneath the enamel. Dentine is softer and more porous than enamel, with lots of tiny tubes that lead to the inside of the tooth.

The pulp is the soft and vulnerable innermost layer, made of nerve tissue and blood vessels.

Decay starts at the enamel and if untreated, progresses through to the dentine and then the pulp. 

As decay progresses it becomes more painful and harder to treat. Catching it early will save you a lot of discomfort and expense. 

Recognising the stages of tooth decay

Stage One: Enamel Lesion 

The first stage of tooth decay is the formation of a small brown or white mark - or lesion - on the enamel.  You probably won’t be able to see it, and it won’t be visible on an x-ray, but your dentist will easily spot it by using a tiny camera. 

  • Does it hurt?

No. There are no nerves or blood vessels in the enamel to signal pain to your brain. If you have tooth decay at this stage, it’s likely you won’t know it. 

That’s why the Australian Dental Association recommends six-monthly dental check-ups so your dentist can spot lesions before they get out of control and require complex, costly treatment down the track.

Caught early enough, it may be possible to reverse the lesion or at least stop it from getting worse.

While you’re in the chair, your dentist may use fluoride, cleaning treatments or a sealant to protect the tooth from further damage, and they will probably send you home with a personalised oral hygiene plan to carry out yourself. 

Stage Two: Enamel Decay

If an enamel lesion is left untreated for too long, it will create a cavity or hole in your tooth - and this is where the problems really begin. 

In Stage Two, the damage is no longer superficial. Your dentist will be able to see how deep the cavity is by taking an x-ray.

  • Does it hurt?

It may or may not. If the cavity hasn’t gone deeper than the enamel, you still might not feel anything. If it is deep and close to the dentine, your tooth may feel more sensitive than normal and you could notice it when you eat cold, hot or sweet foods. 

If your tooth decay has reached this stage, it won’t be possible to reverse it, as the body can’t regrow tooth enamel. But your dentist will be able to stop it from going even deeper and making things much worse. 

The most common way to stop decay working its way into the soft dentine layer is to carefully drill out the decayed part of your tooth and put a natural-coloured filling in that spot ot make your tooth look whole again. This common procedure is a safe, predictable and inexpensive way to fix a cavity.

Stage Three: Dentine Decay

You can probably guess what happens if you don’t catch the decay before it destroys the enamel. The bacteria works its way to the dentine.

Dentine is sponge-like and porous, allowing bacteria to spread quickly and easily. Treatment at this stage is much trickier; you must act fast.

  • Does it hurt?

The short answer is yes, but it may not feel too bad yet.

Stage Three comes with slight toothache or discomfort. At the very least, you will feel sensitive to hot and cold food and drinks. How much it hurts will depend on how far the decay has spread, and on your personal pain tolerance level. 

Your dentist will need to remove the damaged part of the tooth. Depending on the amount of tooth structure that has to go, you may need a filling, a dental crown or an onlay/inlay to make the tooth whole and healthy again. 

Stage Four: Pulp Decay 

If you didn’t stop the decay at the dentine, it will make it right into the soft and vulnerable part of your tooth, the dentine. This is called a root canal infection.

  • Does it hurt

By golly yes. Stage Four tooth decay causes significant pain because the dentine is richly supplied with nerves, blood vessels and connective tissue. 

To stop your pain and clear the infection it is likely your dentist will perform a root canal treatment. This is an intricate procedure that involves drilling into the tooth and removing the infected pulp, then thoroughly cleaning the area and filling the canal in with a special material.

You may also need a dental crown to cap the tooth so it is strong enough to chew properly.

Stage Five: Formation of an Abscess

There is no delicate way to describe a dental abscess. It is a pocket that develops at the tooth root if decay is left untreated for too long. It is filled with pus, extremely painful, and it can have very nasty consequences.  

An abscess won’t go away on its own; you need to see a dentist without delay. The bacteria that are inside your tooth can now spread to your jaw bone, ear and neck and in the most serious cases, the infection can even reach the brain. 

  • Does it hurt?

Excruciatingly. Stage Five is characterised by intense, throbbing pain in the tooth, gums and jaw and it can come with swelling, fever and a bad taste in your mouth. The pain may get worse when you lie down, meaning you could be losing sleep. 

Even if you don’t have all of these symptoms don’t delay getting help. An infection this severe can spread to the brain and throat, and make it difficult to swallow or breathe. In the most terrible cases, it can be fatal. 

To begin treatment, your dentist will take x-rays and assess the extent of the infection. With root canal treatment and antibiotics, it may be possible to save the tooth. But if the situation is too far advanced, your dentist may recommend removing the tooth to prevent further consequences for your health.

It’s important to appreciate that treatment for tooth decay will depend on the stage. Your dentist will need to check your tooth and take some x-rays to give you the right diagnosis and treatment.

The moral of the story

The most important things to take away from this post are:

  • Good dental hygiene (regular brushing, flossing and a healthy diet) can save you a lot of pain and money
  • Six-monthly check-ups give your dentist the chance to stop decay long before you notice it
  • If you have a sore tooth, don’t delay getting treatment as it could become very serious

Think you may have a cavity? At The Grand Arcade Dental Surgery we make sure to spot any potential problems early, saving you from needing costly and complex treatments down the track. 

You can call us on (02) 4862 2162 or book online anytime to get the most convenient appointment time for you.