Can you get rid of cavities?

I didn't think you could, but then i went to the dentist a few weeks ago and my regular dentist wasn't there so some other girl filled in and she said i has 2 cavities!! Then when i went back earlier today to get them filled my regular dentist was there and she checks every tooth twice and she said i only had one cavity?? So i was like woahhhh i'm confusedd!