Cavities are a part of life for most of us, an astounding 86.7% of the population have had a cavity by the age of 39. While many people have had cavities, not many people fully understand what they are or why they get them. A cavity is a general term that is often used to describe several different dental problems such as caries, fractures, erosion, abrasion or abfractions. Fractures are when teeth have broken from trauma, abrasion is when something that has been rubbed on the teeth such as a toothbrush has resulted in the loss of tooth structure, and abfraction is when there has been tooth destruction due to excessive grinding of the teeth. While these are all fairly common problems the main focus in this post will be caries.
Caries are what most of us think of when we talk about cavities. Caries are when the tooth has started to decay and get soft. This process is always fueled by acid. Acid is the main cause of caries in the population. This acid can attack the teeth from many different sources such as bacterial sources, dietary sources, or natural sources. With bacterial sources cavities start when certain types of bacteria in your mouth start to digest sugar and turn it into acid which burns through the enamel of your teeth. Once the bacteria has made it through the first layer of your teeth which is the enamel and into the dentin the process is no longer reversible and a restoration must be put into the tooth after removing the existing decay to help prevent the rest of the tooth from decaying as well. Dietary sources follow the same method of destruction but without out the involvement of bacteria. You will often see dietary destruction of teeth with foods that are highly acidic such as lemon and lime as well as other citrus fruits. Finally, natural sources such as stomach acid can also cause tooth destruction in much the same way for people who have severe acid reflux and people who vomit a lot such as people who have bulimia.
We do have some natural protections to cavities such as our saliva which buffers the acids the come into our mouth and kills some of the acid causing bacteria on our teeth, however good oral hygiene involving brushing twice a day with toothpaste containing fluoride as well as flossing is a cheap and proactive way to prevent cavities. The fluoride in tooth paste helps to remineralize minorly damaged parts of the enamel which has been effected by acid, however once the collagen structure of the enamel is damaged the fluoride can no longer work effectively and a filling must be placed.