You could probably pop the plastic back out. Can you post a pic to help others see what you are working with? I would say you could take this opportunity to look at installing a different bumper (depending on where the dent is). You could do a full replacement, or a partial replacement like the US Offroad Bumper.
The bumper cover is quite easy to take off. Just take some care as to not break some of the clips (like I did). Good luck, and let us know!