Cavities, also called tooth decay or caries, are caused by a combination of factors, including bacteria in your mouth, frequent snacking, sipping sugary drinks, and not cleaning your teeth well.
Many different types of bacteria live in your mouth. A group of harmful bacteria produces acid in your mouth whenever they encounter and digest sugar. Sugar is like a magnet for bad bacteria. These acids remove minerals from the tooth enamel, which is the outer, protective layer of your tooth. When the pH of plaque drops below normal, or less than 5.5, the acidity starts to dissolve minerals and destroy the tooth’s enamel. This process is called demineralization.
If you don’t take care of your teeth and/or you eat and drink lots of sugary or starchy things, your enamel will keep losing minerals. This leads to tooth decay.