#1 always ask to see the cavities a dentist tells you is in yours or your kid's mouth.
#2 if you are still uncertain about a treatment plan, get a second opinion.
#3 if the cavities are smaller, ask about alternative treatment methods and diet modification
On teens with small cavities in between their teeth that are borderline, I'll watch them, put medication on them to delay or even arrest their growth, or prescribe a very high fluoride toothpaste and encourage diet modification. You'd be amazed. Doesn't always work, but we see results.