Tooth decay and cavities: causes, treatment and prevention

Tooth decay can often be prevented. This article explains how decay develops, how it is found and treated, and what you can do every day to protect your teeth. It draws on information from the NHS, the US National Institute of Dental and Craniofacial Research (NIDCR), MedlinePlus and the World Health Organization.

1. Introduction

Tooth decay means damage to the outer surface of a tooth. It happens when bacteria in a sticky film called plaque produce acid. Over time the acid can wear a hole in the tooth, which dentists call a cavity or, in medical language, dental caries ^{[1, 2]}. Decay can happen at any age once teeth have appeared, and it is common in children ^[1].

The World Health Organization reports that decay in permanent teeth is the most common health condition in the Global Burden of Disease study, and that oral diseases affect an estimated 3.7 billion people ^[4]. Most of these problems are largely preventable.

2. Causes and risk factors

The mouth always contains bacteria. After you eat or drink, bacteria in plaque turn sugars and starches into acid. NIDCR explains that this acid pulls minerals out of enamel, the hard outer layer of the tooth. Saliva and fluoride can put some minerals back, but if more minerals are lost than replaced, the enamel breaks down and a cavity forms ^[2].

Factors that raise the risk include:

• Eating or drinking sugary things often, rather than only at mealtimes ^{[1, 2, 4]}
• Not cleaning the teeth and gums regularly ^[1]
• Low exposure to fluoride, a mineral that strengthens enamel ^{[2, 4]}
• Frequent exposure to sugary or starchy food and drink, which keeps enamel losing minerals ^[2]

The WHO adds that high sugar intake, low fluoride exposure and inadequate toothbrushing can lead to decay, pain, tooth loss and infection ^[4].

3. Signs and symptoms

Early decay often causes no symptoms at all, which is why check-ups matter ^{[1, 2]}. As decay gets deeper, people may notice:

• Toothache
• Sharp sensitivity to hot, cold or sweet food and drink
• White, brown or black marks on a tooth
• A visible hole in the tooth

If the infection reaches deep inside the tooth or gum, a painful pocket of pus called an abscess can form. NIDCR notes that an abscess may cause pain, swelling of the face and fever ^[2]. The NHS says a dental abscess needs urgent dental treatment and will not clear up without it ^[5].

4. Diagnosis and tests

Dentists often find decay during routine check-ups by looking at the teeth and checking for soft or sticky areas. NIDCR explains that white, brown or black staining and visible holes are signs they look for, and that X-rays can be used to detect decay ^[2]. MedlinePlus says a dentist asks about symptoms, examines the teeth and probes them with dental instruments, and that dental X-rays may be needed in some cases ^[3].

5. Treatment and management

What is needed depends on how far the decay has gone, and your dentist decides the best option for you.

Early decay

NIDCR explains that decay caught before a cavity forms can be reversed with fluoride treatment from a dentist, because early damage appears as a white spot where minerals have been lost ^[2]. The NHS says early decay may be managed with fluoride treatments such as mouthwash or varnish prescribed by a dentist ^[1].

Cavities

A cavity usually needs a filling. The dentist removes the decayed part of the tooth and fills the space ^{[1, 2]}. If decay reaches the pulp, the soft tissue in the centre of the tooth, root canal treatment may be needed. In some cases a tooth has to be taken out ^{[1, 3]}.

6. Prevention and self-care

The NHS, NIDCR and WHO give very similar advice ^{[1, 2, 4]}:

• Brush at least twice a day with fluoride toothpaste. Spit out the extra toothpaste rather than rinsing with water, so the fluoride stays on the teeth ^[1].
• Clean between your teeth once a day with floss or small interdental brushes ^{[1, 2, 3]}.
• Limit sugary food and drink, and limit snacking ^{[1, 2, 4]}.
• Choose sugar-free versions of medicines where possible, and ask your pharmacist or doctor about this ^[1].
• Avoid tobacco in every form ^{[1, 2, 3]}.
• See a dentist regularly, even when nothing hurts ^{[1, 2, 3]}.

NIDCR also notes that fluoride can come from toothpaste, fluoridated tap water or fluoride mouth rinse ^[2]. Parents can ask a dentist about dental sealants, which cover the chewing surfaces of permanent teeth when they come in and can help prevent decay ^[2].

7. Special groups

Young children can develop early childhood caries, sometimes called baby bottle tooth decay, which usually starts in the front teeth and can spread to the back teeth ^[2]. The NHS stresses that good habits should start early ^[1].

Older adults are also at risk. NIDCR explains that when gums recede, tooth roots are exposed and decay can form on them ^[2].

8. When to see a doctor

See a dentist as soon as possible if you think you or your child has decay. The NHS advises a non-urgent visit for toothache, sharp pain when eating or drinking, or gums that are sore, swollen or bleed when brushing ^[1]. Regular check-ups are advised even without problems ^[1]. NIDCR notes that facial swelling or fever can signal an abscess ^[2]. The NHS advises getting urgent dental help if you think you have an abscess, and going to a hospital emergency department or calling for emergency help if you have trouble breathing, speaking or swallowing, significant swelling inside the mouth, or cannot open your mouth ^[5].

In an emergency, call your local emergency number (112 in India, 911 in the United States).

9. Conclusion

Tooth decay is common but largely preventable. It starts when plaque bacteria turn sugar into acid, and it can often be stopped or reversed if found early. Brushing twice a day with fluoride toothpaste, cleaning between the teeth, cutting back on sugary food and drink, avoiding tobacco and attending regular check-ups are the most useful steps. Your dentist will decide on any treatment you need.