The first thing to do is to rinse your mouth out with warm water. If part of your tooth has broken off, you should try to spit it out to avoid swallowing or biting down on it. Degrees of pain for dental trauma can vary, but if it hurts very badly it's likely that the root itself has been affected. Applying a cold compress to the affected area of your face, and taking over-the-counter painkillers, can help manage your discomfort while you await your appointment.