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Caries and Cavities

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Though the terms are often used interchangeably, caries and cavities are not exactly the same thing. Caries actually refers to the disease process that leads to cavities.

Cause of Caries

Essentially, the cause of caries goes back to bacteria called Mutans Streptococci. In a patient with caries, these bacteria get nourishment from sugar in food, allowing them to produce acids, make plaque and form cavities, eventually causing a need for restorations.

Because bacteria grow by latching onto the sugar left in your mouth from certain foods, a nutritious diet is key in eliminating caries. Simply cutting back on high-sugar items such as sticky candy, sugary cereals, soft drinks, and other high-sugar beverages makes a dramatic difference in your oral health.

Three things are necessary for a cavity to develop:

  • High-sugar foods left in mouth: It’s not just the food but also the duration! The longer sugar sits on the teeth, the more damage it can do.
  • Host response: The bacteria in your mouth can trigger an immune response from your body. Your body’s cells are trying to fight the bacteria, and sometimes a person’s own cells can damage teeth and gums.
  • Bad oral hygiene: Without the preventative maintenance of proper oral care, the bacteria can run rampant and develop fully into a cavity.

When these three factors combine, cavities form, leading to a variety of complications, from discomfort and pain to restorations.

Reasons for Restorations

Typically, when people think of reasons for restorations, they think of caries, and it’s true that caries is one of the main causes. However, caries is just one of many causes for restoration work, including trauma, erosion of enamel, toothbrush abrasion, congenital anomalies, and cosmetic needs. Restoration is a way of replacing missing or lost structure, both for functional and aesthetic purposes.


Whether brought on by a sporting injury, a car accident, or some other kind of violence, dental trauma often requires restoration. Sometimes this involves, for example, repairing a cracked tooth with a filling or a crown. Other times, it may mean reinserting a tooth that’s been knocked out.

There are steps you can take to avoid dental trauma, even beyond practicing good oral hygiene and visiting the dentist regularly. Especially if you’re involved in strenuous physical activity, you may wish to wear a custom mouth guard created by your dentist.

Erosion of Enamel

When the thin outer layer of teeth—enamel—erodes, a tooth loses its strongest protector. This exposes the nerves, leading to increased sensitivity to hot and cold temperatures, discomfort, pain, and sometimes a need for restorations. One of the leading causes for this erosion is a high-acid diet, filled with soft drinks and fruit drinks with phosphoric and citric acids.

Eating Disorders

There are also other more serious causes of enamel erosion, ranging from gastrointestinal disease to eating disorders like bulimia nervosa and anorexia nervosa. If a patient suffers from bulimia nervosa, for example, he or she regularly binges on food and then vomits it in order to control weight gain. One of the many damaging effects of this constant vomiting is that it forces stomach acids into the mouth and thus against the teeth, leading to enamel erosion. Anorexia nervosa leads to both enamel erosion, as well as improper caries response due to abnormal carbohydrate consumption.

Acid Reflux Disorder

What happens in acid reflux disorder is a continual reflux of stomach contents and acids into the oral cavity causes major loss of tooth structure. Usually hard to detect and diagnose, acid reflux disorder often causes severe enamel erosion by the time a patient realizes he or she has the disorder. That’s why early detection by a dentist can be vital not just in treatment and restoration, but also in prevention.

Toothbrush Abrasion

Like erosion, toothbrush abrasion wears away the tooth’s outer coating of enamel. It happens when a patient brushes too hard (often with a hard-bristled brush), or when something scrapes against the teeth. A toothbrush isn’t the only culprit in this type of abrasion; toothpicks may also damage the teeth, as well as removable devices like partial dentures or retainers. You’ll know if you have toothbrush abrasion by looking at the bottom third of your teeth, close to the gums: check for V-shaped marks right in or between teeth.

Cosmetic Reasons

For many people, more attractive teeth make all the difference in how they feel about their overall appearance. Restorations provide a way to achieve that perfect smile through a variety of treatments, such as filling in gaps between teeth, for example, both because it’s more visually pleasing and because it helps prevent food impaction.

Bonding is a specific restoration that improves tooth appearance. In this process, tooth-colored composite resin gets bonded to teeth, which is ideal for closing small gaps. Its beautiful results usually last around five to seven years. For more on bonding, see the chapter on cosmetic dentistry.

Anatomy of a Tooth

To really understand the way restorations work, it’s helpful to take a look at the basic structure of your teeth. While we’re all familiar with the shape and color of teeth, there’s actually a lot more at work.

Three of the basic components of a tooth are enamel, dentin, and pulp.

  • Enamel: The outermost layer of a tooth is a hard, white, translucent substance called enamel. Strong and durable enough to stand up against all the chewing and biting you do on a regular basis, enamel is still easy to crack. Unlike bones, enamel doesn’t repair easily, and that’s why taking care of it is so important.
  • Dentin: Beneath enamel, dentin is a softer substance that makes up the majority of the tooth. While coffee, tea, and poor oral hygiene can stain enamel, the most common teeth stains stem from the dentin. Certain diseases, too much fluoride, or even aging can change the shade of the dentin, making teeth look discolored.
  • Pulp: The middle layer of a tooth is the pulp (or root canal), which houses blood vessels and nerves that feel sensations of temperature and pain.

When Decay Deepens

As decay goes deeper into the heart of a tooth, a filling becomes larger, increasing the chances of the tooth breaking. In some cases, this means a crown has to be fitted over what’s left of the tooth. If the decay extends all the way into the pulp/nerve, a root canal may even be necessary to avoid losing the tooth completely.

Where Cavities Occur

The reality is that cavities can occur on several different surfaces of the tooth, and there are a variety of treatments available, depending upon the extent of decay. In early stages, cavities are best treated with fillings, which can be placed on any surface.

Q: How can I tell if I have a cavity?
A: Depending on how far the decay has spread, you may notice a toothache or increased sensitivity to hot and cold foods or very sweet foods or drinks. It’s also possible for cavities to cause visible holes and/or discoloration and dark spots in the teeth. In the early stages (when detection is key), it can be hard to tell: that’s why dental checkups are so important. Your dentist can see if a tooth feels soft and/or if X-rays show what is not yet visible.

Early Detection Is Key

When it comes to cavities, the sooner you can catch them, the better. The goal is to spot decay in the very early stages so that it can be stopped and treated, and so that you can keep as much of your tooth as possible.


One hot new area of research in the area of restorations is the non-invasive method of remineralization. According to a recent study, this newer treatment provides an effective way to stop and repair early caries by increasing mineral gain during the normal cycles of demineralization and remineralization. Essentially, the way remineralization works is this: calcium and phosphate ions get added to the tooth to encourage mineral gain in the weakened enamel. Rather than merely treating the damage, remineralization offers a way to rebuild what was lost, without any major surgery or painful treatment options.

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