...everything you need to know about orthodontics.
Emergencies during the treatment are very rare, and basically consists on the detachment of any equipment. It can also happen that the arch (wire) moves through the Braces and an end of it is left out rubbing the oral tissue.
In any case, you must warn you dentist to appoint a meeting a soon as possible and avoid waiting until the next appointed visit.
Accidents and knocks in the mouth are also a cause of emergency so do not doubt and tell your dentist about it.