Teeth have a tendency to return to their original positions after orthodontic treatment. This is called relapse. In order to avoid this retainers are provided after treatment. These may be removable or fixed retainers and in many cases both are required. Fixed retainers are made up a thin piece of wire than is cemented onto the back of the front teeth.
Because they are cemented on the back of the teeth they are completely invisible to others. Removable retainers are provided after treatment and need to be worn just in bed at night to hold the alignment of the teeth.