This is very common with braces, and it is nothing to worry about. Twice a day, just brush rigorously (but gently) where the gum meets the tooth, and in circular motions. You should also be flossing each night.
Swollen gums with braces isn’t something to worry about because it is very normal, and even expected, with braces. This is because while your teeth gradually move, there are changes in your gums as well. Don’t worry about the swelling. It is only temporary, as long as you continue to look after your oral health.
Try using a salt water rinse for the swelling. Dissolve 1/2 tsp of table salt in a cup of warm water. Swish in your mouth for one minute, then spit out. Do this each night before bed, and the swelling should subside. If your gums are still swollen and not going down after 4 or 5 days, you need to go back in and see your orthodontist, because something else may be wrong......for more info refer the link..................http://www.identalhub.com/articlecategory-braces-21.aspx