Dental cavities are typically caused by poor oral hygiene. Plaque is a sticky film that develops from food debris, saliva, and bacteria that constantly forms on the surfaces of your teeth. If plaque is not treated and removed, it can harden into tartar, which is more difficult to remove. Tartar buildup can lead to dental cavities by providing a place for bacteria to thrive and damage the tooth enamel. Other factors contributing to dental cavities include dry mouth, frequent snacking, acidic drinks, and certain medical conditions.