Why do I have to wear a retainer at the end of the orthodontic treatment?

Why do I have to wear a retainer at the end of the orthodontic treatment?

Teeth can move throughout life even after orthodontic therapy. This is why it is important to maintain the result obtained after a long journey.
The maintenance braces can be fixed or mobile, it will be the orthodontist who followed the patient during his/her therapy to decide which is the most suitable device.