Tooth Decay

People with diabetes are at greater risk of tooth decay
People with diabetes are at greater risk of tooth decay

Tooth decay, or dental caries, is the demineralisation of teeth. People with diabetes may be more at risk of developing tooth decay due to high blood glucose levels.

For a tooth to decay four factors need to be present at the same point in time: a natural tooth or root surface, sugar, bacteria and plaque.

How common is tooth decay?

Tooth decay is one of the most common diseases in the world, and affects a huge portion of the population.

According to the NHS, around 31% of adults in the UK have visible tooth decay, and around a third of children aged 12 also have decayed teeth.

What causes tooth decay?

Plaque is the film of bacteria that is present on everybody's teeth. It is a 'biofilm', which means it is a colony of bacteria that cover a surface.

Despite what most people think, plaque is not all bad and it is thought that it may help to prevent the growth of pathogenic microorganisms that could cause illness, like flu.

However, problems occur when too much plaque builds up. Bacteria thrive on the sugar available from sweet foods, causing the bacteria to grow and reproduce. The bacteria excrete acid, which demineralises the tooth surface. Small amounts of this won't be noticeable, but when there is a lot of plaque, the acidic secretion can cause more destructive demineralisation of the teeth, known as tooth decay.

A decayed tooth has many appearances depending on the extent of the decay; it can be invisible to see as it occurs between the teeth or underneath a filling or crown, it can also appear white and chalky or become black and brown. Due to the loss of mineralisation of the tooth structure, the tooth can become soft and spongy making it more likely to crumble and break.

Diabetes and tooth decay

Bacteria feed on glucose, and so anywhere there is a lot of glucose, bacteria will thrive. Because of this, people with diabetes are sometimes more susceptible to bacterial infections such as thrush because of the high levels of glucose in their blood.

Bacterial infections in the mouth may be made worse by higher than normal concentrations of glucose in the saliva.

People with diabetes who eat a large amount of high-sugar or carbohydrate foods can have an increased risk of dental decay.


Tooth decay is preventable. Cleaning and brushing well twice a day with a fluoride toothpaste will go a long way towards removing the build up of plaque and stop it progressing past the dangerous point. Using floss or interdental brushes will remove plaque and clean the areas between teeth that can be hard for a toothbrush to reach.

Attending regular appointments with your dentist (the recommended amount is once every six months) is also essential for maintaining good oral health. They will check for decay and monitor the health of your teeth, and give you advice on keeping them healthy.

Keeping good control of blood sugar levels and adopting a healthy diet and will also help to limit the amount of plaque in your mouth down.


A dentist or dental therapist carries out treatment of dental decay. Usually, the decayed area is removed and replaced with a metal filling or a 'composite' filling. The malleability of the fillings let them take on the shape of the original tooth and then set hard.

There are two main types of filling: a metal, or 'amalgam' filling, which is a mixture of metals that harden when mixed, and composite fillings, which are a white substance that harden and blends in with the rest of the tooth. If untreated, the toothache you experience is likely to become more severe as the tooth decays closer to the nerve.

If decay is untreated, it can migrate towards the nerve of the tooth leading to toothache. If decay reaches the nerve your dentist will either need to extract the tooth or perform root canal treatment.

Tooth loss

In extreme cases of tooth decay, the filling won't be able to build the tooth back up adequately, and the tooth may simply have to be removed, or they could fall apart if the demineralization destroys enough of the tooth structure.

Additionally, teeth may simply drop out because of gum disease. Gum disease is a risk for everyone, but diabetics have a lowered ability to fight off infections, so infections can spread and do more damage a lot quicker.

Smoking also greatly increases the risk of tooth loss because of how it damages the gum tissue cells which connect the gums to the teeth. It can also impair blood flow which can slow or halt wounds from healing.

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