I have power chains on my 2 front teeth and they closed rapidly and pushed the gum back and caused a lump of gum behind my teeth, will it go away ?

Most likely: Your body will most likely take care of the extra tissue. It's most likely swollen from being pinched between the teeth. If it doesn't resolve on its own a very simple procedure to remove the painful tissue can be performed by a laser trained dentist. Take some ibuprofen if it is painful and give it a week or so to resolve. Hope this helps!

Swollen gums: Happens most often from combination of compromised gum inflammation (from compromised oral hygiene) and rapid tooth movement. Keep area scrupulously clean and should resolve in a few weeks. If not a Periodontist may need to reshape the tissue, depending on anatomy of frenum, either traditionally or with laser. Report problem to your (hopefully) Orthodontic Specialist or treating Dentist.