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Causes - Gum disease (gingivitis and periodontitis)

Gum disease can be caused by many factors, but poor oral hygiene is the most common cause.

Poor oral hygiene can cause plaque to build up on your teeth. This can happen if you are not brushing your teeth properly or regularly.


Your mouth is full of bacteria. When bacteria combines with saliva it forms a sticky film known as plaque which builds up on your teeth.

When you consume food and drink high in carbohydrates (sugary or starchy foods), bacteria in plaque turn carbohydrates into the energy they need. This process also produces acid at the same time.

Over time, acid in plaque begins to break down your tooth's surface and causes tooth decay.

Other bacteria in plaque can also irritate your gums, making them inflamed and sore.

Plaque is usually easy to remove by brushing and flossing your teeth. But it can harden and form a substance called tartar if it's not removed.

Tartar sticks much more firmly to teeth than plaque. Tartar can usually only be removed by a dentist or dental hygienist.

Risks of developing gum disease

As well as poor oral hygiene, many things can increase your risk of developing gum problems.

These include:

  • smoking
  • your age – gum disease becomes more common as you get older
  • diabetes – a condition that causes a person's blood sugar levels to become too high
  • pregnancy – hormonal changes can make gums more vulnerable to plaque
  • a weakened immune system – because of certain conditions or treatments, such as chemotherapy
  • malnutrition – when a person's diet does not contain the right amount of nutrients
  • stress

You may also be more likely to have gum disease if you're taking medicines that cause a dry mouth. These medicines include antidepressants and antihistamines.

Content supplied by the NHS and adapted for Ireland by the HSE

Page last reviewed: 23 March 2021
Next review due: 23 March 2024

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.