Final answer:
The lower retainer is a dental appliance used to retain the position of teeth after braces removal.
Step-by-step explanation:
The lower retainer, when referring to dental appliances, is a component that is used to retain the position of teeth after the removal of braces. It is typically made of plastic or metal and is custom-made to fit the individual's mouth. The lower retainer helps to maintain the alignment and prevent relapse of the teeth.