Retainers
When we remove your braces, we will begin the retention stage of your treatment. The retention phase typically consists of wearing the retainer full time for 6 months, followed by nightwear only for 6 months. After this phase of treatment, you should still wear your retainer at night as needed indefinitely. Your final orthodontic result depends on your retainers, so follow through with the hard work you’ve put in so far. Remember to remove your retainer before brushing, and brush your retainer before placing it back in your mouth.
Hawley Retainers
This type of retainer may be used for upper or lower teeth. It has two basic parts:
Wires that wrap around the outside surface of teeth. The exact design of the retainer wires will vary somewhat as prescribed by our doctors.
Acrylic (plastic) covers the roof of the mouth and the inside surface of the lower teeth. You choose the color(s) of the acrylic for your retainer. While children generally choose colors, many adults prefer clear or flesh-colored retainers. It’s all up to you!
Hawley retainers can be used to hold or even move teeth slightly.
Invisible Retainers
These retainers are worn when no additional tooth movement is desired. They are lightweight, somewhat flexible, and comfortable. These retainers are very difficult to see these retainers in your mouth and are therefore very esthetic. 
Why are retainers so important?
These are very important devices. Braces move teeth by making them loose in a very controlled and safe manner. Since your teeth are still loose when braces are removed, they must be held or retained until bone slowly fills in around them.
As teeth are moved by braces there are changes that occur in the bone and fibers attached to the teeth. These changes cause teeth to become slightly loose. When braces are removed this “looseness” still exists. This creates an unstable condition in which teeth can move slightly in all directions.
Over a period of months, bone begins to “fill in” around the roots of the teeth causing their positions to solidify. Retainers (or other retention devices) are necessary to hold teeth perfectly straight while this filling in of bone is occurring. If retainers are not worn during this period, the teeth may be out of alignment and become “set” while they are not straight.
What can cause teeth to relapse or become crooked after they have been straightened? More on this website