When teeth are being repositioned through the use of braces, your body needs to undergo some changes, especially in the area around the teeth. This causes a little inflammation that you feel as a soreness. The discomfort arises after 3 to 4 hours of braces placement and usually disappears around 48-72 hours. This feeling is similiar to the sore muscles you feel in your body after going to the gym except in your teeth. They are starting to ¨work out¨and straighten but this feeling quickly goes away.