Your mouth is full of bacteria that combine with saliva to form 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, producing 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 and can usually only be removed by a dentist or dental hygienist.
Who's most at risk?
As well as poor oral hygiene, a number of things can increase your risk of developing problems with your gums.
- your age – gum disease becomes more common as you get older
- diabetes – a lifelong 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 – for example, because of conditions like HIV and AIDS or certain treatments, such as chemotherapy
- malnutrition – a condition that occurs when a person's diet does not contain the right amount of nutrients
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.