Most dents, even large creased dents, can be repaired using today's Paintless Dent Repair methods. However, to be certain you should contact a professional PDR technician. Some very small dents cannot be repaired, if the dent is in the wrong location.
The Paintless Dent Repair industry has sufficiently scared the auto body industry and they are now scrambling to change your perception. In fact, virtually every one of the major auto body franchises has created websites dedicated to Paintless Dent Repair. They pretend to offer the service so they can convince you, it isn’t repairable, using the PDR method. Don't get ripped off. Call a professional to see if they are willing to give you an assessment, before calling your insurance company and dropping some serious money on a repaint.
Paintless Dent Repair does have some significant limitations, in areas near the edge of a panel, in what professionals call a zero access panel. That is, the sheet metal won't allow a tool to get behind the dented panel because it is enclosed on all sides. You typically find these in your vehicle's roof rails or in the top of most doors. They are blocked off to add reinforcement to protect the occupants. However, from a Paintless Dent Repair perspective, they may not be reparable. Usually, and for very specific types of damage, a technician can use a process known as glue pulling, which is limited on creases.