Also known as tooth decay or caries, cavities are areas on the hard surface of the teeth that become damaged and form small holes or openings. They are caused by multiple factors, such as bacteria in the mouth, damage from substances like sugary snacks or drinks and poor oral health habits. If left untreated, they can increase in size and further harm the tooth; this can eventually lead to the need for root canal treatment (if the decay reaches the root of the tooth) or removal of the tooth altogether (if there is not enough healthy material left to salvage). When cavities first form, they are small and generally not painful, which makes them hard for a person to notice on their own. This is why it is important to see a dentist for regular cleanings and exams.