That's a tough one.
Sometimes yes, sometimes no.
Is it a fabric dimple or is the hardsided portion behind the material also dented?
Dimples can be steamed occassionally on fabric. Dents sometimes lessen over time by just the passage of time, or being stuffed with paper or hung up in a way to further the process. But I have found once a hardsided bag has a dent, there will always be a little crease or mark there no matter how much time has passed.
Unless someone has some "magic" potion??
Chris