Plaque is a soft, pale yellow, sticky substance that builds up on the surfaces of teeth if you don't brush them regularly. It can cause tooth decay and gum disease. Plaque builds up on the teeth - it tends to collect in protected areas such as in between the teeth, and in the grooves on the biting surfaces of back teeth (called fissures).

After a few days of not brushing, plaque can start to make teeth feel rather 'furry', and they can begin to look slightly yellow and sometimes green. If you looked at plaque under a microscope, you would see that it contains lots of tiny bacteria living in a sticky substance.

You can remove plaque yourself using a toothbrush and fluoride toothpaste. You need to take special care over hard to reach areas such as between teeth, and your dentist or hygienist can tell you how to do this.

Calculus / Tartar

Calculus (or tartar) is plaque that has been left on teeth for a long time and gone hard. It builds up on teeth like scale inside a kettle, and this can make the teeth feel rough and look unsightly. It tends to form where the teeth meet the gums, and in between teeth, and you can watch this happening on the model. Also, you often see it behind the bottom front teeth (near where the salivary glands squirt out their saliva).

You won't always be able to tell if you have calculus, so you really need to go to the dentist to get your teeth checked regularly. Calculus is too hard to remove yourself with a toothbrush, and so it needs to be removed properly by a dentist or hygienist using special cleaning tools. You can help prevent calculus forming by keeping your teeth clean.

Tooth decay

Tooth decay (caries) is very common, and affects people of all ages. A hole (or cavity) forms in a tooth and an abscess forms at the root tip when the hole gets very large.

How does tooth decay happen?

Tooth decay can occur if plaque is left on teeth. It is the tiny bacteria which live in plaque that cause it to happen. When tooth decay first starts, the bacteria make acids (which they let out into the plaque), and which soften the tooth's surface. The acids actually dissolve away the minerals in the tooth's outer surface (or enamel), and this process is known as demineralisation.

Bacteria need to feed on the sugars in food and drink that we consume to make this happen (sugars such as sucrose, glucose and fructose). Once all the sugar has been used up after eating or drinking something sweet, the acid in plaque gradually disappears and the tooth has a chance to repair itself (called remineralisation). The minerals in saliva help this to happen, and so does the fluoride in toothpaste. If plaque (containing the bacteria) is not removed regularly, or if sugar is eaten too often, then plaque bacteria can keep producing more and more acid, and the tooth doesn't get a chance to repair itself properly. Eventually a small hole (or cavity) appears, like the one shown in the model.

What can happen next?

As more and more acids are produced, the hole gets bigger and bigger, and goes deeper towards the living part of the tooth (called the pulp). This makes the tooth more and more sensitive, especially to hot and cold things. Eventually, when the hole gets large enough, the pulp becomes damaged and can die to leave an empty space inside the tooth where the pulp used to be. Bacteria from the mouth can get inside the tooth and cause an infection (known as an abscess) at the very end of the root (or root tip).

Did you know?

  • Tooth-brushing with a fluoride toothpaste helps to remove plaque, and prevent this from happening.
  • Also, cutting down on sugary foods and drinks helps protect teeth, especially if you only have them at mealtimes.
  • Dentists can repair holes in teeth with fillings, and help prevent them getting too big and painful.

Gum disease

Gum disease is a common problem, and is often why people lose their teeth. Look at the model to see the effects of gum disease and how the tooth eventually has very little bone around it to hold it in place.

How does this happen?

The plaque that collects where the teeth meet the gums can make the gums red, and a bit swollen (this is called gingivitis). It can also make gums bleed a little when you brush.

When it first starts (usually during early adulthood), gingivitis can be treated easily by brushing teeth properly and regularly. This will also help to prevent gingivitis coming back.

What can happen next?

If teeth and gums aren't properly cleaned for a very long time, the bone underneath the gums (which holds the tooth's root in place) can start to shrink back. Plaque causes the bone around the teeth to start dissolving away, downwards towards the root tip. Gaps appear between the teeth and gums during this process (called pockets), and the dentist can measure these using a special measuring instrument (called a probe). As the bone disappears, the gums covering it shrink back too. It takes a very long time (many years), but eventually all the bone holding the tooth in the jaw disappears, and the tooth becomes loose and may fall out.

Tooth erosion

Tooth erosion is caused by acidic foods and drinks 'dissolving' away the surface of the tooth. It is becoming increasingly more common, especially due to greater consumption of fizzy drinks - including 'diet' brands.

Erosion caused by foods and drinks

Acids in the mouth can dissolve away tooth surfaces. Given the chance, teeth will repair themselves, using minerals from saliva. But if acid is in the mouth too often, teeth cannot repair themselves and the hard tooth surface (the enamel) becomes thinner - this is called 'erosion'.

The teeth can then become extra sensitive to hot and cold food and drink. Eroded teeth can also be more likely to suffer decay.

The main cause of erosion is too frequent consumption of certain kinds of food and drink. All fizzy drinks (including 'diet' brands and fizzy mineral water), all 'sports' drinks, all squashes and all fruit juices are acidic to varying degrees. Pickles and citrus fruits are examples of acidic types of food.

Some medicines are acidic and, therefore, erosive.

And people with some illnesses (such as eating disorders) may suffer from erosion because of frequent vomiting, as stomach acids also erode teeth. For this reason, dentists may ask about eating disorders if they see teeth that are very badly eroded.

Here are some key tips to prevent erosion

  • Try and avoid consuming acidic food and / or drink too often during the day. Try to have them only at mealtimes.
  • Drink acidic drinks quickly - don't sip them. And don't swish them round your mouth.
  • Between meals you should only have 'safe' drinks, which are not sugary or acidic. Milk and water are 'safe' drinks. So are tea and coffee if you do not add sugar to them (you can use non-sugar sweeteners).
  • You should try and avoid snacking between meals. If you do snack, only have 'safe' snacks, which are not sugary or acidic. Fruits, vegetables and products (such as sandwiches, toast, crumpets and pitta bread) are all 'safe' snacks. You should try and avoid snacking between meals. Some fruits, especially citrus fruits, are acidic and are known to cause erosion if they are consumed in large quantities. This is not normally a problem for most people; however, you could discuss with your dentist or hygienist the safest way of enjoying these fruits.
  • Because acids temporarily soften the tooth surface, don't brush your teeth immediately after eating or drinking something acidic.
  • You should brush your teeth twice a day, and always use a fluoride toothpaste.
  • Your dentist can identify erosion, pinpoint the causes and advise you how to prevent further damage.


Very bad toothache is often caused by a tooth abscess. When a hole (or cavity) in a tooth gets large enough, the living part of the tooth (or pulp) becomes damaged. The pulp can then die leaving an empty space inside the tooth where the pulp used to be. Bacteria from the mouth can get inside the tooth and cause an infection (known as an abscess) at the very end of the root (or root tip).

This infection can then spread to form an abscess around the root tip. The infection inside the tooth's root (or root canal) builds up and eventually spreads into the bone at the end of the root canal (root tip) to form a rounded area which can usually be seen on an x-ray. Toothache caused by an abscess often lasts for long periods, and the tooth may well be tender to bite on.

Abscesses often become increasingly more painful, and sometimes the infection spreads even more to form a bump on the gum overlying the root ("gumboil"), or sometimes it causes a swollen face.

Did you know?

Dentists can often save a tooth with an abscess by carrying out a root filling.
You won't always know if you have a tooth abscess, as they are not always painful.

Dry mouth

Xerostomia is a condition where the mouth becomes very dry. This can be rather unpleasant for some people, and make people more susceptible to dental problems such as tooth decay and problems wearing dentures.

There are lots of different reasons why people get dry mouth, and there are things that you can do both to ease the condition and help prevent problems with your teeth.

It can lead to dryness, a burning or sore feeling in the mouth or a bad taste, dentures becoming loose and causing sore areas, difficulty swallowing and speaking, and more chance of getting tooth decay.

Some prescription drugs and medicines can cause dry mouth as a side effect, especially treatments for depression and high blood pressure. Also, certain medical conditions affect the salivary glands, so they don't produce as much saliva and the mouth tends to be more dry.

Making sure you don't get dehydrated by drinking plenty of fluids can help. Also, doctors can prescribe artificial saliva which comes as a spray to help moisten the mouth. Talk to your doctor about possibly changing the drugs you take so there are less side-effects. Some people find sugar free chewing gum or sugar free sweets help produce more saliva.