If you have recently had any type of orthodontic treatment, it is quite common and very important to wear a retainer once your braces are removed. Since the teeth continue to move throughout your life, supporting them after your orthodontic treatment will help them stay in place and will maintain the hard work you did while you were undergoing treatment.
There are two main classes of retainers, tehy are bonded retainers that will be attached to the teeth and removable retainers that can be taken out to clean and eat. Both types of retainers will help to stabilize the teeth and bones after treatment to ensure that the realignment of your teeth and your bite do not change.
Most orthodonists will recommend or require you to wear a removable retainer for at least a year after you have your braces taken off. You will likely be told to wear it all the time for at least the first four to six months and then nights only to help keep your teeth in place.
The exact time frame will depend on your particular situation. Make sure that you follow the instructions given to you by your orthodontist.