Cavities (Tooth Decay): Causes, Symptoms, and Treatments

What is a Cavity?

A cavity is a hole in your tooth caused by tooth decay. Cavities develop when bacteria in your mouth consume sugars from food and drinks, producing acids that gradually erode (dissolve the minerals from) the enamel, the protective outer layer of your teeth.

This erosion exposes the softer, more vulnerable dentin layer underneath your enamel to bacteria, eventually creating a hole (or cavity) in your tooth.

If untreated, tooth decay can reach the pulp — the deepest part of the tooth that holds nerves and blood vessels — potentially causing severe pain, swelling, abscesses, or even tooth loss.

What Does a Cavity Look Like?

The appearance of a cavity depends on the severity of the tooth decay. In the early stage of decay, the first sign is often a small, white spot on a tooth's surface, which indicates mineral loss (demineralization). These spots may look chalky, especially when your mouth is dry.

As the cavity progresses, the spot will further discolor, turning yellow or brown. At this point, you may feel a pit in your tooth. Once the cavity reaches the dentin (the softer, more porous layer beneath the enamel), there will be a visible hole in your tooth, and the spot will likely turn black.

Eventually, the decay will reach the pulp of your tooth (the part that contains nerves and blood vessels). When this happens, the cavity will be large and dark. You might also experience some swelling in the area.

What Causes Cavities?

Plaque and Acid

The main cause of cavities is the plaque that builds up on your teeth and the acids produced by bacteria forming plaque.

How does plaque start? Bacteria in your mouth accumulate to form plaque, a soft, sticky, colorless or pale-yellow film. Bacteria within the plaque film consume sugars and produce acids that dissolve the minerals in your tooth's protective enamel, leading to tooth decay and cavities.

Diet

Another major cause of cavities is your diet — especially sugary, starchy foods and drinks. These provide glucose that feeds the bacteria forming plaque.

Sugary, starchy foods and drinks do two things that contribute to plaque formation (and, eventually, cavities):

1. They serve as a source of energy for bacteria
2. They provide a sticky place where bacteria can gather

Here are some common foods and drinks that contribute to cavity formation:

• Soft drinks
• Juice
• Candy
• Bread
• Pasta
• Potatoes
• Citrus fruits
• Tomatoes
• Coffee
• Tea
• Dried fruit
• Cheese
• Milk
• Ice cream

While foods like milk and cheese contain calcium beneficial for teeth, they also contain natural sugars (lactose) that plaque bacteria can use for fuel. Acidic foods like citrus and tomatoes can also weaken enamel directly.

Though it's important to maintain a healthy diet, you can still occasionally enjoy these foods and not worry about tooth decay if you maintain a good oral hygiene routine.

Poor Oral Hygiene

Poor oral hygiene makes you more prone to cavities and tooth decay. Plaque needs to be removed every day to prevent it from accumulating in your mouth and causing problems.

We recommend using an electric toothbrush twice daily, partnered with flossing and rinsing with an antibacterial mouthwash at least once every day.

Dry Mouth

Dry mouth is a condition (or, sometimes, a symptom of a condition) caused by reduced saliva production.

Without enough saliva, your body can't neutralize the acids in your mouth as effectively. Plaque can more easily build up on your teeth, leaving you vulnerable to tooth decay and cavities.

Dry mouth may be a sign of a medical issue, so talk to a doctor or dentist about possible treatments.

Receding Gums

If you have receding gums, plaque can form near the roots of your teeth. These root surfaces are covered by a layer called cementum, which is softer than enamel and more vulnerable to decay.

To prevent cavities under these circumstances, it's especially important to maintain a good oral hygiene routine, so plaque doesn't build up on the unprotected parts of your teeth.

Signs and Symptoms of Cavities

Tooth Sensitivity

When plaque acid starts to eat away at your tooth enamel, it can make your teeth more sensitive to foods and drinks that are hot, cold, sweet, or sour.

Toothache

A persistent toothache or throbbing in your jaw can be an early sign of a cavity.

Discoloration

White, brown, or black discoloration on your teeth is a sign that you may be suffering from tooth decay.

Visible Holes or Pits

In some cases, you may be able to see small holes or pits in your teeth — especially on the front, back, or sides. This is a sure sign that you have a cavity and should see a dentist as soon as possible.

Pain when Chewing

Pain when chewing is another symptom of tooth decay. As decay progresses closer to the inner pulp of the tooth where the nerve resides, the tooth can become more sensitive to the pressure of chewing.

Bad Breath or a Bad Taste in Your Mouth

If bacteria and food debris accumulate in a cavity, it can cause bad breath or a persistent bad taste in your mouth. The smell or taste comes from the gas that the bacteria release as they feed off food debris and soft tissue.

Cavity and Tooth Decay Treatments

Fluoride Treatment

In the early stages of tooth decay — when the enamel is just beginning to erode — a fluoride treatment can help remineralize the protective layer around your teeth and reverse plaque damage.

For the best results, see a dentist for a professional cleaning, checkup, and fluoride treatment.

Filling

Once a hole forms, treating the cavity typically requires a more invasive procedure, such as a filling.

During the procedure, a dental professional will remove the decayed portion of your tooth and fill the space with hard material (e.g., composite resin, amalgam, or porcelain) to prevent the tooth decay from spreading.

Crown

If a cavity gets too big, you may need a filling and a crown. A crown is a cap made to cover the entire tooth. After removing the decayed material and filling the hole, adding a crown restores the tooth's shape, size, and strength.

Root Canal

When tooth decay reaches the pulp—the soft tissue inside the tooth that contains nerves and blood vessels—your dentist may recommend a root canal. This procedure is performed to save the tooth and prevent the need for an extraction.

During this procedure, your dentist will remove the infected pulp, clean and disinfect the inside of the tooth, and seal it up with a filling and (possibly) a crown.

Tooth Extraction

In cases where your tooth can't be saved, your dentist may recommend removing the tooth completely. After the extraction, your dentist may discuss replacement options with you, such as a dental implant, bridge, or dentures.

How to Prevent Cavities and Tooth Decay

Maintain a Good Oral Hygiene Routine

The absolute best way to prevent cavities and tooth decay is to maintain a good oral hygiene routine.

This consists of:

• Brushing your teeth at least twice a day (or after every meal) using toothpaste made with stannous fluoride
• Flossing once a day
• Rinsing with mouthwash once a day (or more if needed)

The purpose of this routine is to remove the plaque and bacteria that sticks around after you eat so it doesn't start eroding your enamel.

Use an Electric Toothbrush

Electric toothbrushes have been shown to remove more plaque and food particles than manual toothbrushes. So, if you're serious about preventing cavities and tooth decay, use an electric toothbrush as part of your oral hygiene routine.

Use a Stannous Fluoride Toothpaste

To prevent mineral loss in your teeth, use toothpaste that contains stannous fluoride. Stannous fluoride helps prevent cavities by slowing the breakdown of enamel and speeding up the remineralization process.

Visit Your Dentist at Least Twice a Year

Visit your dentist at least twice a year for a professional cleaning and checkup. They can tell you how well your oral hygiene routine is working, give you tips to improve, and remove any plaque and tartar that you may have missed.

Limit Sugary, Starchy, and Acidic Foods and Drinks

Another great way to prevent cavities and tooth decay is to limit your intake of sugary, starchy foods and drinks that serve as fuel for bacteria.

Consuming less goes a long way toward keeping cavities from forming in the first place and preventing them from turning into more advanced tooth decay.

Drink Plenty of Water

Drinking water throughout the day can help rinse away the bacteria and plaque buildup that lead to cavities and tooth decay. Drink at least eight cups of water every day to keep your body hydrated and help prevent tooth decay.

Kick Cavities to the Curb with Oral-B!

Help avoid cavities and tooth decay by maintaining healthy teeth and gums with a good oral hygiene routine. The right toothbrush can make a huge difference — like one from the Oral-B iO Electric Toothbrush Series, which removes 100% more plaque than a manual brush.

Our innovative iO Magnetic technology combines micro-vibrating bristles with our dentist-inspired round brush head for a professional clean feeling every time.

With smart pressure sensors, custom modes, and guided brushing, the Oral-B Electric Toothbrush Series can help you prevent cavities and keep your smile healthy.