The Anatomy of a Cavity

What is a cavity?

A cavity is a breakdown of healthy tooth structure by bacteria found in the mouth. When you eat foods high in sugars or carbohydrates, bacteria found on your teeth and in your saliva eat them too. These bacteria break down sugar as food and release acid as a byproduct. This acid, when it contacts teeth, begins to degrade the tooth’s hard but thin enamel coating; and once a hole is made through the enamel, bacteria can invade the soft dentin underneath and a new cavity is born!

Not all cavities are the same, however. The depth and severity of a cavity have a big effect on your symptoms and necessary treatment. Let’s explore the progression of cavities, their signs and symptoms, and some potential treatment options.

Enamel demineralization

Enamel demineralization is the early beginning of a cavity. Bacteria have just begun to break down a tooth’s enamel but have not yet reached the dentin underneath. These lesions are often without symptoms but show up on dental x-rays and as opaque white spots on your teeth that stand out from other healthy tooth structure.

This early demineralization is not usually treated with a filling. With thorough and regular brushing using fluoridated toothpaste, daily flossing, and switching to a diet low in carbohydrates, demineralization can be reversed and healthy enamel restored.

Decay approaching dentin

Decay approaching dentin is nearly a cavity. Bacteria have demineralized enough enamel to get close to the dentin underneath. Teeth at this stage are not yet painful, but the lesions will be visible on x-rays and are often detectable during an exam by your dentist. Taking action with teeth at this stage is recommended to prevent cavities from developing.

Teeth with minor decay have a few noninvasive treatment options. In simple cases, brushing with a prescription high fluoride toothpaste and changing your home care routine may be enough to restore the enamel. If minor decay is in the grooves of your back teeth, your dentist may recommend a preventative resin restoration as treatment. These are shallow preventative restorations that do not require anesthetic but are able to remove small amounts of affected enamel and seal the tooth off from future decay.

Decay into dentin

Once bacteria have invaded the dentin underneath enamel, a cavity has developed. These teeth are sometimes sensitive to hot, cold, and sweets as they no longer have a coating of enamel to protect them from the oral environment. Other times, they have no symptoms at all. Even though symptoms are often minor, immediate treatment of teeth with cavities is recommended because bacteria can spread through dentin quickly, weaken the affected tooth, and make treatment more difficult.

Cavities have a range of treatments determined by the spread of bacteria within the dentin of a tooth. Small and shallow cavities are treated with fillings. Cavities that are larger and weaken the cusps of your teeth may require a crown to restore the full strength of your tooth. The treatment that is right for you will be determined following x-rays and an oral examination.

Decay into the nerve

Untreated cavities into dentin will continue to grow deeper until they reach the nerve located in the center of a tooth. Teeth with decay into the nerve often have severe hot and cold sensitivity that lingers, pain on chewing, and leave a sour or rotten taste in your mouth. Occasionally, facial swelling is present as the infection abscesses from the tooth to surrounding tissues. Sometimes these teeth have no pain or pain that changes in intensity. In all cases, immediate treatment is recommended as pain and swelling can derail your day at best and result in a medical emergency at worst.

Treatment for decay into the nerve is most often a root canal. The infected nerve is removed and the canals cleaned and sealed. A crown is then placed over the tooth to restore its full strength and prevent future breakdown. If decay extends too deep and affects the root of the tooth, pulling the tooth and replacing it with an implant may be recommended.