What Are Cavities?

Dr. Omar El-Mowafy
Authored By:
Dr. Omar El-Mowafy

Cavities, also known as dental caries, develop when carious lesions form within the tooth, causing tooth decay. This occurs when there is breakdown in the surface of the tooth, or enamel, through dentin which allows a lesion to form inside the tooth. The breakdown of the enamel can be caused when teeth undergo fracture or when there is a loss of substance due to abrasion or erosion. It is more commonly caused when the normal bacteria in the mouth metabolize carbohydrates left over from food debris to produce acids.  These acids attack the surfaces of the teeth, and slowly cause demineralization through loss of calcium and phosphorous with the subsequent formation of carious lesions. Lesions can develop on any tooth and on any surface, including the inner surface, the outer surface, chewing surfaces, in between the teeth, or even just above the root of the tooth. The lesion starts at the enamel and slowly progresses towards dentin. A cavity is fully-formed once the lesion passes through the dentin-enamel junction into dentin.

Depending on the depth of the cavity, you may experience pain because the lesion can affect the nerves of the tooth. This typically happens when the carious lesion approaches the dentino-enamel junction as enamel has no nerve endings while dentin has.  If the nerves of the teeth are unaffected, as when the lesion is still in enamel, you may be completely unaware of the fact that you have a cavity until it is diagnosed by your dentist. In order to diagnose and assess a cavity, your dentist will perform a clinical and radiographic examination. This will inform the dentist of where and how large the cavity is, enabling your dentist to prepare your treatment plan.

When operative intervention is needed, the dentist will first numb the area with anaesthetics, and then remove the decayed material inside the tooth using drills and other hand instruments. Depending on your treatment plan, there are various materials that can be used to fill your tooth. If the dentist fills your tooth immediately after drilling, the treatment is referred to as a direct restoration.  With a direct restoration, your dentist will either use silver amalgam, or composite resin which will closely match the colour of your tooth.

This decision depends on the location and size of the cavity as different materials present different properties, as well as on your preference. On the other hand, if your dentist takes an impression of the prepared cavity rather than filling it the same day, the treatment is referred to as an indirect restoration. With an indirect restoration your dentist will create a mold of your teeth which will be sent to a lab to create the filling material. The filling materials typically include porcelain and gold. Once the filling is created and sent back to your dentist, you will be called back in for another appointment so that the filling can be cemented to your tooth. With either type of restoration the filling placed in your tooth will restore the tooth’s original form and function.

To prevent the formation of cavities, it is important to follow good oral hygiene by brushing at least twice a day, and flossing at least once a day. Brushing after every meal would be ideal. Also, try to avoid sugary foods and drinks as they will increase the amount of acid in the mouth and increase your chances of getting cavities. Regular visits to your dentist are recommended to, not only prevent cavities through regular cleanings, but also to allow the early detection of problems, such as inadequate oral hygiene or early carious lesions, that might lead to the development of cavities. Early carious lesions can be successfully-treated with fluoride through remineralization which eliminates the need for having them drilled and filled.