It does work buttt, only for small pressure dents that air will pop out faster.
tried it on a chamber once . In the chest freezer over night and some of the dents popped out before it blew the plugs out.
Water expands as it freezes then contracts as it gets colder. Bit is, you have little or no control over the ice method where as with air you have a bit more control and add heat and u can remove larger dents