Enamel can repair itself by using minerals from saliva and fluoride from toothpaste or other sources. However, if the decay process continues, more minerals are lost. Over time, the enamel weakens and is destroyed, forming a cavity. A cavity is permanent damage that the dentist must repair with a filling.
Can cavities go away on their own? No. However, you can stop the first stage of tooth decay with good oral hygiene. Once a decay crosses the enamel and changes the physical shape of the tooth, the only option is to see a dentist. It is physically and scientifically impossible for the tooth to grow back in that space.
Cavities don't go away without intervention. The pain may come and go at first, but that doesn't indicate that the cavity has healed on its own. If you want to stop the progression of the cavity and avoid further pain in the future, you need the help of a dentist. In the early stages of tooth decay, when only enamel is involved, tooth decay can be reversed.
Once a SMALL cavity has formed, tooth decay can sometimes be stopped, only with close attention to cleaning and using fluoride to remineralize the tooth. The cavity will remain as the tooth structure will not grow back. Tooth decay and the subsequent development of tooth decay occur when teeth are exposed to acids produced by oral bacteria. Cavities won't go away without intervention, which means you should seek professional help if you suspect you have a cavity.
However, cavities can go away if you interrupt them during the earliest stage of dental demineralization.