Tooth decay


Tooth decay


Tooth decay is a common problem that occurs when acids in your mouth dissolve the outer layers of your teeth.

It is also known as dental decay or dental caries.

Although levels of tooth decay have decreased over the last few decades, it is still one of the most widespread health problems in the UK.

It's estimated that around one in every three adults in England have tooth decay and a survey of five year old children carried out in 2012 found that more than one in four had some degree of tooth decay.


Signs and symptoms

Tooth decay may not cause any symptoms until it has reached an advanced stage. As the problem develops, symptoms of tooth decay can include:


tooth sensitivity – you may feel tenderness or pain when eating or drinking something hot, cold or sweet

grey, brown or black spots appearing on your teeth

bad breath

an unpleasant taste in your mouth

If left untreated, tooth decay can lead to further problems such as a cavities (holes in the teeth) gum disease or dental abscesses (collections of pus at the end of the teeth or in the gums).


When to see your dentist

Toothache is a warning that something is wrong and that you should visit your dentist as soon as possible. If you ignore the problem it may get worse, and you could end up losing a tooth.

Even if you don't have any noticeable problems with your teeth, it is still important to have regular dental check-ups so your dentist can check for early signs of decay. Tooth decay is much easier to treat in its early stages.

Adults over 18 should have a check-up at least once every two years and people under the age of 18 should have a check-up at least once a year. Your dentist may suggest having more frequent check-ups if you have had a history of dental problems, or you are thought to be at a higher risk of developing tooth decay.

Dentists can usually identify tooth decay by examining your teeth, although occasionally an X-ray may be carried out to check for any cavities or abscesses.


What causes tooth decay?

Your mouth is full of bacteria that combine with small food particles and saliva to form a sticky film known as plaque.

When you consume food and drink high in carbohydrates – particularly sugary foods and drinks – the bacteria in plaque turn the carbohydrates into energy they need, producing acid at the same time.

If the plaque is allowed to build up, the acid can begin to break down the outer surface of your tooth and can eventually enter and damage the soft part at the centre of the tooth.


How to prevent tooth decay

Although tooth decay is a common problem, it is often entirely preventable. The best way to avoid tooth decay is to keep your teeth and gums as healthy as possible.

To do this, you should:

brush your teeth with a fluoride toothpaste twice a day, spending at least two minutes each time

use floss or an interdental toothbrush at least once a day to clean between your teeth and under the gum line

avoid rinsing your mouth with water or mouthwash after brushing because this washes the protective toothpaste away – just spit out any excess toothpaste

cut down on sugary and starchy food and drinks, particularly between meals or within an hour of going to bed


How tooth decay is treated

If you see your dentist when the decay is in the early stages, your dentist may apply a fluoride varnish to the area to help stop further decay.

If the decay has worn away the outer layer of your tooth and caused a cavity, your dentist will remove the decay and refill the hole in your tooth with a filling. If the nerve in the middle of your tooth is damaged, you may need root canal treatment, which involves removing the nerve and restoring the tooth with a filling or crown.

If the tooth is so badly damaged that it cannot be restored, it may need to be removed.


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Causes of tooth decay 

Tooth decay occurs when a sticky acidic film called plaque builds up on your teeth and begins break down the surface of your teeth.

How tooth decay develops

Your mouth is full of bacteria, which combine with small food particles and saliva to form plaque.

When you consume food and drink high in carbohydrates – particularly sugary foods and drinks – the bacteria in plaque turn the carbohydrates into energy they need, producing acid at the same time.

Regularly cleaning your teeth can remove plaque, but if it's allowed to build up, it can begin to break down the surface of your tooth.

The plaque will first start to soften the enamel (the hard outer coating of a tooth) by removing minerals from the tooth. Over time, a small hole known as a cavity can develop on the surface. This will cause toothache.

Once cavities have formed in the enamel, the plaque and bacteria can reach the dentine (the softer, bone-like material underneath the enamel). As the dentine is softer than the enamel, the process of tooth decay speeds up.

Without treatment, plaque and bacteria will enter the pulp (the soft centre of the tooth that contains nerves and blood vessels). At this stage, your nerves will be exposed to bacteria, making your tooth very painful. The bacteria can also infect tissue within the pulp, causing a dental abscess.

Tooth decay typically occurs in teeth at the back of your mouth, known as molars and premolars. These are large flat teeth used to chew food. Due to their size and shape, it is easy for particles of food to get stuck on and in between these teeth. They are also harder to clean properly.

It is more common for a front tooth to be affected by tooth decay when it is touching another tooth alongside it.


Increased risk

There are a number of factors that can increase your risk of tooth decay. These include:



Eating food and drink high in carbohydrates, particularly snacking regularly between meals, will increase your risk of tooth decay.

Tooth decay is often associated with sweet and sticky food and drink – such as chocolate, sweets, sugar and fizzy drinks – but starchy foods – such as crisps, white bread, pretzels and biscuits – also contain high levels of carbohydrates.

Some medications can also contain sugar, so it's best to use sugar-free alternatives whenever possible.


Poor oral hygiene

If you do not regularly brush your teeth and clean between them with floss or an interdental brush, you are at a higher risk of tooth decay. You should brush your teeth at least twice a day using fluoride toothpaste.


Smoking and alcohol

People who smoke and drink alcohol regularly are at an increased risk of tooth decay.

This is because tobacco can interfere with production of saliva, which helps keep the surface of your teeth clean, and alcohol can contribute to the erosion of tooth enamel.


Dry mouth

People who have lower levels of saliva in their mouth are at higher risk of developing tooth decay, because saliva helps to keep the surface of your teeth clean and can neutralise acids in your mouth.

A number of medicines, medical treatments and health conditions can lower the amount of saliva in your mouth, including:

tricyclic antidepressants (TCAs)


some antiepileptic medicines

some antipsychotic medicines



Sjogren's syndrome – a condition where the body’s immune system attacks glands that secrete fluid, such as the tear and saliva glands

If you are taking a medicine, receiving treatment, or have a medical condition known to cause dry mouth, it's particularly important to maintain good oral hygiene and ensure you stay well hydrated.


Treating tooth decay 

The treatment for tooth decay largely depends on how advanced the problem is.

If your decay is in the early stages, your dentist may apply a fluoride varnish to the area to help stop further decay.

If decay has worn away your enamel (the hard outer coating of a tooth) and led to a cavity, your dentist will remove the soft decay and replace the hole in your tooth with a filling. If the nerve in the middle of your tooth is damaged, you may need root canal treatment, which removes the nerve and restores the tooth with a filling or crown.

If the tooth is so badly damaged it cannot be restored, it may need to be removed.



Fluoride is probably the most effective treatment available for preventing and limiting the spread of tooth decay. It is a naturally occurring mineral found in foods and drinks, such as fish and tea, but it can also be synthesised (manufactured).

Synthetic fluoride is used in toothpaste, from which most people get their fluoride, and small amounts of it are added to the water supply in some areas of the country.

Fluoride protects teeth by strengthening the enamel, making teeth more resistant to the acids that can cause tooth decay. It reduces the ability of plaque bacteria to produce acid, and enhances the repair (remineralisation) of enamel.

If your cavity is in its early stages, your dentist may be able to prevent further decay by applying a concentrated fluoride gel, varnish or paste to any affected teeth.


Fillings and crowns

If the decay to one of your teeth is more extensive, it may be necessary to repair the damage with a filling or crown.

A filling replaces your missing enamel. There are many different filling materials available, including amalgam (silver coloured), composite (tooth coloured) and glass ionomer (tooth coloured).

Inlays and onlays can also be used to fill teeth. They specifically fill the size and shape of your cavity, and are fixed in place with dental cement. Inlays and onlays are usually made from gold, as it is the most long-lasting and hard-wearing filling material.

Crowns are used to treat extensively damaged teeth. The decayed section of the tooth is drilled away and the crown is placed over the remaining section. Crowns are made of metal, porcelain, or a combination of the two.


Root canal treatment

If tooth decay has spread to the pulp (the soft centre of the tooth), the pulp may have to be removed and replaced with an artificial pulp that will keep the tooth in place. This is known as root canal treatment.

Root canal therapy has had a reputation of being painful, but improved dental techniques mean it is now relatively painless.


Tooth extraction

In serious cases of tooth decay, the tooth may be removed to prevent the spread of infection.

Losing certain teeth can affect the shape and function of surrounding teeth, so the dentist may have to replace the tooth with a partial denture, bridge or implant.


 dental costs

charges are set by the government and are standard for all patients. Charges are assessed each year and usually change every April.

From April 1 2014, dental charges are £18.50 or £50.50 for most courses of treatment. The maximum charge for a complex course of treatment is £219.00.

There are several ways of paying for dental treatment, including many types of payment plan that allow you to spread your payment over time. Some people do not have to pay for dental treatment, including those receiving benefits, children, pregnant women and nursing mothers.


Preventing tooth decay 

Maintaining good oral hygiene through brushing and flossing your teeth is one of the most effective ways to prevent tooth decay.

Some simple changes your diet can also help.



Brush your teeth for at least two minutes last thing at night before you go to bed and on one other occasion every day. Apart from bedtime, it doesn't really matter when the other time you brush your teeth is – providing it's at least an hour after you last ate.

Don't brush your teeth straight after a meal as it can damage your teeth, especially if you've had fruit, fizzy drinks, wine or any other food that contains acid. Leaving an hour will give your saliva a chance to neutralise the acid.

It is also important you brush your teeth in the right way. The following advice may help:

Place the head of your toothbrush against your teeth, then tilt the bristle tips to a 45 degree angle against the gum line. Move the brush in small circular movements, several times, on all the surfaces of every tooth.

Brush the outer surfaces of each tooth, upper and lower, keeping the bristles angled against the gum line.

Use the same method on the inside surfaces of all your teeth.

Brush the chewing surfaces of the teeth.

To clean the inside surfaces of the front teeth, tilt the brush vertically and make several small circular strokes with the front part of the brush.

Brushing your tongue will freshen your breath and clean your mouth by removing bacteria.

Do not rinse your mouth with water or mouthwash after brushing as this washes the protective toothpaste away. Just spit out excess toothpaste.

Try not to eat or drink anything for 30 minutes after brushing.

It is important to replace your toothbrush on a regular basis because they wear out and become less effective in removing plaque. Most toothbrushes need to be replaced every two to three months.

It doesn't matter whether you use an electric or manual toothbrush. They're both equally as good, providing you brush with them properly. However, some people find it easier to clean their teeth thoroughly with an electric toothbrush.



Flossing is an important part of oral hygiene. It removes plaque and food particles from between your teeth and under the gum line, where a toothbrush cannot always reach.

You should ideally clean between your teeth at least once a day with floss. This can be done before or after brushing your teeth at night.

Your dentist or hygienist can advise you on flossing techniques, but the following tips may help:

Take 12-18 inches (30-45cm) of floss and grasp it so you have a couple of inches of floss taut between your hands.

Slip the floss gently between the teeth and into the area between your teeth and gums, as far as it will go.

Floss with 8-10 strokes, up and down between each tooth, to dislodge food and plaque.

You can use interdental brushes instead of flossing, especially if your teeth are very close together and you find it difficult to manoeuvre dental floss through the gap.



Using an alcohol-free dental mouthwash that contains fluoride can also help prevent tooth decay.

However, this should not be used directly after brushing your teeth. Choose a separate time to use mouthwash, such as after lunch. Do not eat or drink for 30 minutes after using a fluoride mouthwash.



Limiting the amount of sugar you eat and drink is important to prevent tooth decay and also has wider benefits for your general health. Have sugary food and drink only at mealtimes and don't eat sugary snacks between meals.

Most of the sugars we eat and drink are contained in processed and ready-made food and drinks. These include:

sweets, chocolate, cakes and biscuits

buns, pastries and fruit pies

sponge puddings and other puddings

table sugar added to food or drinks, such as tea

sugary breakfast cereals

jams, marmalades and honey

ice cream

dried fruit or fruit in syrup

syrups and sweet sauces

sugary drinks, including soft drinks, fizzy drinks, milkshakes, alcoholic drinks and fruit juice

Healthier alternatives for snacks and drinks include cheese, fruit and vegetables, and unsweetened tea or coffee. Some artificial sweeteners have been shown not to contribute to toothy decay, so they may be a good alternative if you like to add sugar to any foods or drinks.

Chewing sugar-free gum after you have eaten may also help prevent tooth decay. When you chew gum, your mouth produces saliva, which neutralises the acid in your mouth before it can damage your teeth.

Some medicines can contain sugar too, so you should ideally use sugar-free alternatives whenever possible. Your GP or pharmacist should be able to advise you about this.


Checking food labels

Check labels on foods to see how much sugar they contain. Sugar comes in many forms, so look out for the following ingredients:







hydrolysed starch or syrup

Ingredients are usually listed in order of the amount used, with the main ingredient listed first. If sugar, or one of the ingredients above, is near the top of the ingredients list, it may mean the food is high in sugar.

Some products also use the traffic light system as part of their labelling to indicate whether they are high or low in sugar, where a red light indicates a high amount of sugar and a green light indicates a low amount of sugar.

In general, high in sugar means more than 15g of sugar for every 100g of product and low in sugar means less than 5g of sugar for every 100g.