As previously mentioned in these FAQs, a bit of discomfort is to be expected, but it shouldn’t be a continually gnawing pain that prevents you from opening or closing your mouth.
Call your orthodontist if pain persist even after taking some ibuprofen, and if you feel any major discomfort from loose brackets, distorted wires, or wires that are poking the inside of your cheeks. If an orthodontic appliance is making it hard for you to breathe, call your dentist immediately for a dental emergency.