Dental cavities are caused when the tooth is exposed to acid produced by specific bacteria in your mouth. The bacteria that cause cavities turn sugar from your diet into acid that etches into your teeth. The acid from the bacteria eats away the calcium and other minerals that are part of normal, healthy tooth structure. Luckily, your saliva carries minerals, like calcium, and antibodies to fight these bacteria. The saliva takes care of most of the bacteria but there are still tiny hiding places that saliva can’t rinse very well. Those hiding places are mostly deep valleys on the chewing surfaces of your teeth and between your teeth right below where they touch. Your toothbrush reaches and flushes the deep valleys on the chewing surfaces of your teeth and flossing will remove the bacteria between your teeth. This is why brushing and flossing are both so important.
Over time the acid creates actual holes in your teeth. If the cavity is less than 0.5mm deep, it may be reversible with focused, proper cleaning. If the cavity is much deeper than 0.5mm, the cavity usually is NOT reversible. In order to stop the cavity from becoming large and possibly breaking the tooth and/or causing pain, a form of treatment will be recommended specific to your situation.