Once the cavity is formed, it is not possible to bring back the teeth without cavity as you expect.all you can do is prevent formation of caries in remaining teeth by-
-Maintaining good oral hygine-proper brushing (early morning&before going to bed ),(after sticky food like chocolates, sweets ,)
- Diet with calcium & vitamines.(MIlk,salads,fruits etc).
Treatment of should start earliest. -Temporary filling,cement filling,silver filling are the steps of filling.(the silver/amalgum filling is permanent.
-Deep caries can be treated by Root canal treatment
After the treatment you have to be careful by proper brushing. Also visit your dentist
every 6 month &have regular check up. .
- Mind it -Badly Infected caries teeth may need extraction.