After going through a year or two of orthodontic treatment, teeth need to be kept in place when the brackets are removed by wearing retainers. Retainers can either be removable or fixed and will be decided on both by the doctor and the patient. Fixed retainers are cemented permanently at the back of front teeth, either on the upper or on the lower or both. Removable retainers can be made of clear plastic that looks similar to a bleaching tray, or it can be made of acrylic with metal wires. It is recommended to use retainers every day, usually at night, to avoid a relapse of teeth moving.