tooth decay / cavities / dental caries

How does tooth decay form? If tooth decay is a location on a tooth where its mineral content has been dissolved away and a hole has formed (a process called demineralization), how does this action occur? The answer is, the demineralization of a tooth is caused by acids, acids that are created by certain types of bacteria that live in our mouths. Bacteria are living organisms just like we are. As you know, humans consume food and produce waste products that are subsequently excreted. Bacteria do the same thing. The bacteria that are capable of causing cavities (mutans streptococci and lactobacilli) consume sugars as food (glucose, sucrose, fructose, lactose, or cooked starches). The waste products these bacteria create from having consumed these sugars are the acids (especially lactic acid) which cause a tooth's demineralization (tooth decay formation). The bacteria that live in our mouths eat when we do. So, as we ingest foods which contain sugars (such as soda, candy, milk, and even fruits and vegetables or the juices made from them) the bacteria get a meal too, and within minutes they start producing the acids which cause tooth decay.

Tooth Decay, Cavities,    & Dental Caries : Page 1 What is tooth decay? Page 2 How does tooth decay form? Page 3 How long does it take a cavity to form? Page 4 How does fluoride help to prevent tooth decay? Page 5 Tooth decay and children. Page 6 Tooth decay and adults.

Oral bacteria and dental plaque: location, location, location. Everyone's mouth is inhabited by bacteria, in fact a single human mouth can contain more microorganisms than there are people on planet Earth. While you can't sterilize your mouth you can minimize your potential for the formation of tooth decay. This is done by way of not allowing the bacteria that are present to form organized colonies on the surface of your teeth. These colonies are called "dental plaque".

Dental plaque not only provides living quarters for bacteria but it also helps to hold the acid produced by these bacteria up against the tooth's surface. Take a look at our diagram to the left. Acids created by bacteria that lie near the surface of the dental plaque will possibly seep out off the plaque's surface and into our mouths. This acid will get diluted, buffered, and/or washed away by saliva and the foods we eat and drink and isn't the acid that will be especially instrumental in actually forming tooth decay.

The acid which will demineralize a tooth and hence cause tooth decay formation is the acid which seeps in the other direction, on through the plaque down to the tooth's surface. This acid will be held right up against the tooth and because down at this depth there is less dilution, buffering, or washing away by saliva the acid will be in very concentrated form (a pH of 4 or lower).

As time goes by the buffering agents found in saliva can penetrate through dental plaque and neutralize the acids which are present, however this can take as long as two or more hours.

The amount of demineralization that the acids can cause is related to the age of the dental plaque that is present. The age of dental plaque relates to its thickness, chemical nature, and what types of bacteria inhabit it. In response to an identical exposure to sugars, plaque which is only a few hours old will produce much less tooth demineralization than plaque which is several days old.