2TheApex: Use an Endo Z bur or another non-endcutting bur
A non-endcutting bur can still cut through Cavit or IRM easily. The bur smooths the walls of the access and is a safe way to remove the restoration and any cotton pellets. Here’s short video of it being done. It’s not recommended to run the handpiece for very long with the cotton pellet wrapped around it. The Endo Z bur is from Tulsa Dentsply. I use it on most cases for access once I know I have entered the pulp chamber.