Post-orthodontic care is important because if it is not done, there is a danger that the teeth will simply revert to their old positions once you remove the braces. This is because teeth are held in positions by ligaments known as periodontal ligaments. Even when braces help to position your teeth the way you want them, it takes a while for these ligaments to firm up and hold your teeth in one place. For that reason, orthodontists will recommend that you wear a retainer which holds the teeth in place and helps the ligament to firm up in the correct position.