How Long Does It Take To Get A Small Cavity Filled. A cavity usually starts long before it's identified in the dentist's office. A small cavity can become a root canal in six months or less, but this depends on several factors.
A larger filling or multiple fillings can take longer. How long it takes to fill a cavity will depend on the severity of your cavity, the location of your cavity, and the type of filling you get. Cavities are the end result of tooth decay, which occurs when dental plaque (a layer of food particles, bacteria, and minerals) persists on the tooth’s surface because of inadequate dental hygiene.
You have no other choice then to have the tooth filled.
The sooner the easier it is to fix. If your filled tooth is sore, brush and floss gently around it as instructed by your dentist. While some cavities are small, painless, and can take a while to progress, many can get much worse rather quickly if treatment is delayed. In general, a filling takes an hour or less.