You call it... An external mouth guard.
buy a new mouth guard
You take them out because if you keep them in and have a mouth guard in the denture cuts your mouth all up.
no
wallmart
arthur wood
Sometimes it's tobacco, other times it's a mouth guard designed to improve balance http://news.bostonherald.com/sports/baseball/red_sox/view.bg?articleid=1095682
Mouth Piece, its used as a guard for your teeth.
a mouth guard
Yes
A mouth guard
Usually football