Many people wonder what causes cavities; they want to know how to avoid this common problem that leads to discomfort, pain and tooth loss. Cavities result from tooth decay, a process involving multiple stages. According to the Mayo Clinic, it begins when bacteria inflicts damage on the hard surface of the teeth, and the destruction will spread into the deeper layers if left unchecked. If you are cavity-prone, take heart because the issue is largely preventable. Regular care of your teeth and a healthy diet can be enormously helpful in warding off this decay of your pearly whites.