What causes cavities?
Bacteria in your mouth combine with food and saliva to form a sticky substance called plaque. Over time, the plaque breaks down the tooth’s protective enamel. The holes in the enamel can grow larger and larger forming a cavity. Cavities only become painful when they are very large and starting to destroy nerves and blood vessels within the tooth. This can lead to an abscess which requires attention from a dental professional.Plaque is a big part of the equation, because it enables bacteria to adhere to teeth. (Teeth are mostly smooth, and there’s saliva in mouth, so you need something sticky to bind to teeth) What actually causes cavities is the byproduct/waste product of bacteria- acid (mainly lactic). Acid is produced at the end of carbohydrate fermentation. Acid causes de-mineralization of enamel, weakening the enamel first and later destroying the enamel matrix. Caries will spread into enamel, and eventually into dentin, which is not as dense as enamel. Once bacteria reaches the dentin layer, it can really spread fast, and bigger. Nerves will be irritated by bacterial toxin and become sensitive to temperature since the protective enamel layer is missing. (enamel does not transmit temperature too much, thus protecting the pulp). Most people perceive pain, only when the cavity has already become very large.
Also, three things are required for caries formation: 1) bacteria, 2) a diet for bacteria (sugar! Bacteria need to eat to grow and multiply), 3) susceptible host or tooth surface.
How to avoid cavities
Carbohydrate foods containing sugars feed the bacteria in the tooth plaque. Although cavities generally take months or years to form, regular brushing and flossing immediately after eating or drinking sugary foods—or at the very least rinsing—helps control decay. Dentists also recommend limiting foods and drinks high in sugar to mealtimes after which oral hygiene can be performed.