Tooth Decay Causes, Symptoms and Treatment


Tooth decay and cavities affect the majority of people at some point in their lives. More than 91% of US adults aged 20–64 have cavities, and a quarter of all cavities haven’t been treated. According to the National Institute of Dental and Craniofacial Research, tooth decay is the most prevalent chronic disease in both children and adults in America, even though it is largely preventable.

So if you’re worried about the state of your teeth, you’re certainly not alone. Fortunately, if caught early, it’s easy to treat decay and prevent an oral cavity from developing. If left untreated, decay can lead to more serious dental problems like abscesses and tooth loss.

In this guide we explain what tooth decay is, what causes it, and how it can be prevented and treated. You can also discover how it leads to cavities, and ways to stop the infection developing this far.

The condition is worryingly common in children too, so we’ve included some information on how to recognise the signs, what to do if your child has a cavity, and how to prevent further damage to their teeth.

What is tooth decay?

Bacteria in your mouth collect in a sticky film on your teeth known as plaque. These bacteria feed off sugary foods and drinks and produce acid. If you don’t keep your teeth clean, this acid will start to eat away at the surface of your tooth.

dental caries stages
Decay attacks the tooth layer by layer

The outer layer of your tooth, called enamel, is a strong substance which your body can replenish over time. But once the build-up of bacteria reaches a certain point, your body can’t keep up and your tooth enamel starts to decay. The medical term for decaying teeth is dental caries.

Plaque most often gathers around the gum line, along the edges of existing fillings, where teeth connect, and in the ridges on the biting surfaces of teeth.

Plaque can be removed from teeth by brushing and flossing, but if left for long enough it hardens into a substance called tartar. This is a breeding ground for those acid-producing bacteria, but tartar can only be removed with a proper dental cleaning. If not removed, it can lead to gum disease – often accompanied by bleeding gums.

What is a cavity?

Once there is a hole in the enamel of your tooth, the bacteria can spread to the inner layers of dentin and pulp. These have no way of fighting decay, so the infection can spread rapidly. The resulting hole in the tooth is called a cavity.

Simply put, we can define a cavity as a hole that forms inside a tooth when decay is left to spread. It only takes a tiny hole in the enamel for a large cavity to form inside the tooth.

If the cavity spreads to the dental pulp inside the decayed tooth it causes pulp inflammation and starts to kill off the nerves and blood vessels. In the end, the tooth itself dies and becomes discolored.

The bacteria can also form an abscess at the root of the tooth or in the surrounding gum tissue. The infection may eventually spread into other parts of the body through the blood stream, causing serious health problems.

What causes tooth decay?

yellow plaque deposit
Plaque builds up and harbors tooth-destroying bacteria

We are all susceptible to dental caries if we don’t take care of our teeth. Causes of decay in teeth include:

  • Consuming foods and drinks that are high in sugar or carbohydrates
  • Eating a lot of citrus fruits, which are very acidic
  • Drinking acidic beverages such as soft drinks and sports drinks
  • Snacking in between meals
  • Poor oral hygiene
  • Smoking
  • Failing to have regular dental checkups
  • Not cleaning teeth properly while wearing braces

The good news is that these factors are all things that you can work to improve. By controlling what you eat and drink, cleaning your teeth well, and visiting the dentist regularly you can reduce the chances of your teeth decaying and developing cavities.

Remember, our teeth decay because of the bacteria contained in plaque as well as acid from other sources. If your teeth feel sticky or furry, it’s probably because of plaque. Try scraping your fingernail along a tooth and you might remove a white or clear substance.

The longer that plaque stays on your teeth, the more risk there is of dental decay.

Signs of decay in teeth

What does tooth decay look like? In the early stages, decay will appear as a small white or brown spot on your tooth. You may not be able to notice this but your dentist knows what to look for.

That’s why it’s so important to go for regular checkups; a dentist can catch early dental caries and treat it quite easily, but if you wait until you notice a hole in your tooth, the damage has already spread much further.

tooth pain
Toothache is a common oral cavity symptom

Aside from visible damage to your teeth, symptoms of tooth decay include:

  • Toothache (although pain is usually mild at first)
  • Pain when chewing or biting
  • Sensitivity to hot or cold foods and drinks
  • Bad breath that doesn’t go away
  • A nasty taste in your mouth

If you notice any of these tooth decay symptoms, book an appointment with your dentist so the problem can be addressed sooner rather than later.

How to know if you have a cavity

You may be able to see a dark spot on your tooth or feel a hole with your tongue or fingernail.

Cavity pain is usually more severe than early tooth decay pain because the infection has reached the nerves in the tooth pulp. However, if you ignore this pain it may disappear by itself. This doesn’t mean that the infection is gone; in fact it has spread so far that it has destroyed the nerves completely.

Other dental cavity symptoms include increased sensitivity to hot and cold foods and drinks. If you find yourself in pain when you take a sip of cold water, for example, your teeth may need some attention.

Ultimately, only your dentist can check the condition of your teeth and accurately assess how far any damage has spread. He or she will then advise you on the best course of treatment.

How to prevent tooth decay

cavity causes
Fizzy drinks can be doubly damaging because of the sugar and acid they contain

The best way to avoid oral cavities is to prevent decay altogether. As we have already mentioned, you can stop dental decay by controlling what you eat and drink and maintaining good oral hygiene.

Here are some more tips for caring for your teeth:

  • If you do drink sugary or acidic drinks, use a straw to minimize contact with your teeth
  • Chew sugar-free gum containing xylitol after meals if you are unable to brush
  • Change your toothbrush regularly – ideally every three months
  • Use a fluoride toothpaste
  • Take a multivitamin that contains calcium, magnesium and vitamin D

You may also use a mouthwash which contains antibacterial ingredients and added fluoride. However, many oral professionals advise not using mouthwash directly after brushing teeth. This is because it will wash away the minerals in your toothpaste, making them less effective.

Similarly, rinsing your mouth with water after you brush will dilute the ingredients in your toothpaste which are designed to protect teeth against decay.

In this video you can find more information on how to brush your teeth properly.

Is it possible to stop and reverse decay?

If you have already spotted the early signs of dental caries, you might be wondering how to get rid of tooth decay without visiting the dentist.

The enamel in our teeth can remineralize itself to a certain degree. If you cut damaging foods and drinks out of your diet and make changes to improve your oral health, this will give your enamel a chance to replenish the lost minerals and reverse tooth decay damage.

Your dentist can also provide treatments to stop decay without having to drill your tooth. These treatments include fluoride gel, antiseptic varnish and fissure sealants.

So it is possible to stop tooth decay once it has started, as long as you catch it early. However, if you can see a hole that reaches inside the tooth, or you are already experiencing toothache, you probably have a cavity, meaning you will need dental treatment.

Cavity and tooth decay treatment

tooth caries and cavity
Badly decayed teeth may need to be extracted

If a tooth has decayed beyond the point of natural healing, it will require a filling to stop the infection spreading any further.

The treatment process will depend on how far inside the tooth the decay has spread. Your dentist may need to take an x-ray to assess the size and extent of the cavity, especially if you have a cavity between teeth that is hard to see.

If you catch the problem in the early stages, before the enamel layer has been fully eroded, your dentist may be able to remove the decay and apply a small filling without you needing an anesthetic injection. This is because there are no nerves in tooth enamel.

In cases where the infection has spread further, your dentist will administer an anesthetic to prevent pain during your tooth cavity filling. For a small cavity, treatment is usually straightforward and takes less than 30 minutes.

If dental decay has spread into the pulp chamber and tooth root, you will need root canal treatment to remove all of the decayed material. Your dentist may recommend you get a crown on your tooth to strengthen it and protect against further damage.

Where decay is widespread and there is very little healthy tooth left, your dentist will remove the decayed tooth completely. You can avoid this by visiting your dentist as soon as you experience any tooth decay symptoms, though.

If you need to have a tooth extracted, your dentist will explain the options for replacing it with an artificial tooth. These include dentures, bridges and tooth implants.

Treatment costs for a tooth cavity

There are different costs to consider when getting an estimate for filling a tooth cavity. Medicaid assistance programs for low-income individuals are run by each individual state, so coverage is going to vary depending on which state you live in. Medicare doesn’t cover most dental care, and this includes fillings for cavities. The good news is that if you have dental insurance, your policy might cover all or part of the associated costs:

Treatment Purpose Estimated cost
Checkup Identify problems and give oral health advice $120
Apply fluoride varnish Protect against decay $40
Tooth filling Remove decay and repair tooth $165
Root canal Remove decay deep inside tooth $900
Extraction Remove badly decayed tooth $150
Crown Protect tooth after damage or treatment $1100
Bridge Replace a missing tooth $600


tooth fillings
Choose between silver or tooth-colored fillings

Prices will vary depending on the size of the filling, if you have a silver cavity filling or a filling with white composite material, and where you receive treatment.

Fair Health Consumer provides detailed dental care cost estimates based on your location and whether or not you have insurance coverage.

Tooth decay in children

Sadly, between 60% and 90% of children around the world have teeth cavities. In poorer countries decayed teeth are common due to the lack of available health care. According to the National Children’s Oral Health Oral Health Foundation (NCOHF), more than 40% of children in the US have cavities by the time they reach kindergarten.

Ways that parents can help prevent toddler and child tooth decay include:

  • Be aware of how much sugar is in their food – not just sweet foods but things like pasta sauces and fruit juices
  • Limit snacking between meals to foods that aren’t high in sugar or carbohydrates (raw vegetables and fruits are ideal)
  • Supervise tooth brushing until your child is seven or older
  • Use a toothpaste that contains fluoride
  • Take them for regular dental checkups so any problems can be treated early

The NCOHF website has some more useful tips for parents on how to prevent cavities in children and. This will not only lower their chances of dental decay and cavity pain; their oral health will benefit in many ways.

Treating children’s teeth

dental caries child
There are ways to limit decay in children’s teeth

It can be distressing to realize your child has a tooth cavity, but the sooner you visit the dentist the greater your chances of being able to reverse the damage. Baby teeth are particularly good at remineralizing themselves, so your toddler or child may not require a filling.

Your dentist will advise you on how to stop decay in your child’s teeth. They may apply a fissure sealant, which covers the grooves in the back teeth which are particularly at risk of decay.

Dentists also recommend applying a fluoride varnish at least twice a year for children aged three and over. Younger children may receive this treatment if the dentist thinks it is necessary. This varnish protects teeth from bacteria and gives time for recovery from existing decay.

If your child does need a filling, it’s quite possible they won’t need an injection. If they do, the dentist will apply a numbing gel to the gum so they don’t feel any pain from the needle.

Even if you feel nervous about your child or toddler getting a filling, try to stay calm and positive. Your little one will pick up on how you are feeling. If they think that visiting the dentist is a bad thing, this might deter them from seeking the dental care they need later in life.

To conclude

This is a problem that few of us will successfully avoid completely. Dental caries can be treated simply and even reversed if you seek treatment early on. The longer you put off visiting a dentist after you notice caries and cavity symptoms, the more extensive (and costly) your treatment is likely to be.

Follow the tips in this article for improving your oral health and managing your food and drink intake, and you should at least reduce your chances of getting a dental cavity, even if you don’t prevent decay completely.

Tooth Decay Causes, Symptoms and Treatment
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