There are some ways by which you can arrest the cavities but they are not sure shot methods.  it will be like taking a chance  what will help is visit your dentist to check for cavities & then he/she will be in a better position to help you.  Meanwhile you can use ACCLAIM/toothmin toothpaste, or Tooth mousse. but it's always better to do anything only after getting a clinical examination done.

Hello, You need to visit a dentist and let him take a call if any fillings are required,only a pit and fissure sealant is sufficient or any remineralising agents will help at this stage. Regards DR SUMAN MAKAM

To re mineralize enamel there are some tooth pastes available like GC Tiothmouse ,Toothmin, Elgydium etc.But in my opinion please visit a dentist and let him or her evaluate properly. May be pit n fissure sealant will be a good choice.