Operculectomy is the removal of the gum tissue which sometimes forms a flap over a partially erupted tooth (usually the lower 2nd molars). This gum tissue flap is called an operculum. Since it is difficult to properly clean the tooth under the operculum, a cavity can form in that area.
This procedure is also done to treat pericoronitis, a condition characterised by pain and inflammation of the operculum. Pericoronitis typically occurs among young adults, especially those whose wisdom teeth are starting to erupt.