Tooth Decay

Tooth decay is damage that occurs when germs (bacteria) in your mouth make acids that eat away at a tooth. It can lead to a hole in the tooth, called a cavity. If not treated, tooth decay can cause pain, infection, and tooth loss. According to the World Health Organization, between 60 and 90 percent of school-aged children and almost 100 percent of adults have dental cavities. Risk factors for oral diseases, such as dental cavities, gum disease, oral cancers, and oral infectious disease, include unhealthy diet, tobacco use, excessive alcohol use, and poor oral hygiene. Dental hygienists recommend maintaining a low level of fluoride in the oral cavity to protect against dental cavities. 

A tooth has three layers:

• The hard outer layer is called enamel.
• The middle layer is called dentin.
• The center of the tooth is called the pulp. It contains nerves and blood vessels.

The more layers that are affected by decay, the worse the damage.

Causes

Cavities are caused by tooth decay, a process that occurs over time. Here's how tooth decay develops:

• Plaque forms. Your mouth naturally contains many types of bacteria. Some thrive on food and drinks that contain certain forms of sugar. When these sugars aren't cleaned off your teeth, the bacteria quickly begin feeding on them and producing acids. The bacteria, form bacterial plaque — a sticky film that coats your teeth. If you run your tongue along your teeth, you may be able to feel this plaque forming — it's slightly rough and it's more noticeable on your back teeth, especially close to your gums. If the plaque is not removed while it's soft, it becomes hard and difficult to remove — a good place for bacteria to hide.
• Plaque attacks. The acids in plaque remove minerals in your tooth's hard, outer enamel. This erosion causes tiny openings or holes in the enamel — the first stage of cavities. Once areas of enamel are worn away, the bacteria and acid can reach the next layer of your teeth, called dentin. This layer is softer than enamel and less resistant to acid.
• Destruction continues. As tooth decay develops, the bacteria and acid continue their march through your teeth, moving next to the inner tooth material (pulp) that contains nerves and blood vessels. The pulp becomes swollen and irritated from the bacteria. When decay advances to this extent, you may have a severe toothache, sensitivity, pain when biting or other symptoms. Your body also may respond to these bacterial invaders by sending white blood cells to fight the infection. This may result in a tooth abscess — a pocket of pus that's caused by a bacterial infection.

Symptoms

Tooth decay usually doesn't cause symptoms until you have a cavity or an infected tooth. When this happens, you may have:

• A toothache, which is the most common symptom.
• Swelling in your gums near a sore tooth. This can be a sign of severe tooth decay or an abscessed tooth camera.gif.
• Bad breath or a bad taste in your mouth.
• White, gray, brown, or black spots on your teeth.

If you have a toothache, see a dentist. Sometimes the pain will go away for a while, but the tooth decay will keep growing. If you don't get treatment, your cavities could get worse and your tooth could die.

Risk Factors

Everyone who has teeth is at risk of getting cavities, but the following factors can increase risk:

• Tooth location. Decay most often occurs in your back teeth (molars and premolars). These teeth have lots of grooves, pits and crannies that can collect food particles. As a result, they're harder to keep clean than your smoother, easy-to-reach front teeth. Plaque can build and bacteria can thrive between your back teeth, producing the acid that destroys tooth enamel.
• Certain foods and drinks. Foods that cling to your teeth for a long time — such as milk, ice cream, honey, sugar, soda, dried fruit, cake, cookies, hard candy, breath mints, dry cereal, and chips — are more likely to cause decay than foods that are easily washed away by saliva.
• Frequent snacking or sipping. When you steadily snack or sip sodas, you give mouth bacteria more fuel to produce acids that attack your teeth and wear them down. And sipping soda or other acidic drinks throughout the day helps create a continual acid bath over your teeth.
• Bedtime infant feeding. Parents are encouraged not to give babies bedtime bottles filled with milk, formula, juice or other sugar-containing liquids. These beverages will remain on teeth for hours while your baby sleeps, providing food for decay-causing bacteria. This damage is often called baby bottle tooth decay. Letting a toddler who's transitioning from a bottle wander around drinking from a sippy cup can cause similar damage.
• Inadequate brushing. If you don't clean your teeth soon after eating and drinking, plaque forms quickly and the first stages of decay can begin.
• Not getting enough fluoride. Fluoride, a naturally occurring mineral, helps prevent cavities and can even reverse the earliest stages of tooth damage. Because of its benefits for teeth, fluoride is added to many public water supplies. It's also a common ingredient in toothpaste and mouth rinses. Bottled water may not contain fluoride.
• Younger or older age. In the United States, cavities are common in children and teenagers. Older adults also are at higher risk, as more of us keep our teeth as we age. Over time, teeth can wear down and gums may recede, making teeth more vulnerable to root decay. Older adults also may use more medications that reduce saliva flow, increasing the risk of tooth decay.
• Dry mouth. Dry mouth is caused by a lack of saliva, which helps prevent tooth decay by washing away food and plaque from your teeth. Substances found in saliva also help counter the acid produced by bacteria and can even help repair early tooth decay. Certain medications, some medical conditions, radiation to your head or neck, or certain chemotherapy drugs can increase your risk of cavities by reducing saliva production.
• Worn fillings or dental devices. Over the years, dental fillings can weaken, begin to break down or develop rough edges. This allows plaque to build up more easily and makes it harder to remove. Dental devices can also stop fitting well, allowing decay to begin underneath them.
• Eating disorders. Anorexia and bulimia can lead to significant tooth erosion and cavities. Stomach acid from repeated vomiting (purging) washes over the teeth and begins dissolving the enamel. Eating disorders can also interfere with saliva production.
• Heartburn. Heartburn or gastroesophageal reflux disease (GERD) can cause stomach acid to flow into your mouth (reflux), wearing away the enamel of your teeth and causing significant tooth damage. Your dentist may recommend that you consult your doctor to see if gastric reflux is the cause of your enamel loss.

Treatment

If you see your dentist when the decay is in the early stages, your dentist may apply a fluoride varnish to the area to help stop further decay.

If the decay has worn away the outer layer of your tooth and caused a cavity, your dentist will remove the decay and refill the hole in your tooth with a filling. If the nerve in the middle of your tooth is damaged, you may need root canal treatment, which involves removing the nerve and restoring the tooth with a filling or crown.

If the tooth is so badly damaged that it cannot be restored, it may need to be removed.

Prevention

Although tooth decay is a common problem, it is often entirely preventable. The best way to avoid tooth decay is to keep your teeth and gums as healthy as possible.

To do this, you should:

• brush your teeth with a fluoride toothpaste twice a day, spending at least two minutes each time
• use floss or an interdental toothbrush at least once a day to clean between your teeth and under the gum line
• avoid rinsing your mouth with water or mouthwash after brushing because this washes the protective toothpaste away – just spit out any excess toothpaste
• cut down on sugary and starchy food and drinks, particularly between meals or within an hour of going to bed