Urgencies in orthodontics fortunately very rarely happen. The most common problems are:
1) The orthodontic wire sticks a bit out and irritates the mucous membrane. To fix that, a small orthodontic wax pellet (available in pharmacies) should be applied on the irritated zone, while waiting too visit the practioner.
A metal wire got loose after brushing. Here again, wax can be useful, but you can also try replacing it with a small tweezer.
2) Moderate pain during 72 hours after the appointment are considered «normal». The orthodontist always prescribes analgesics (e.g. paracétamol)
3) The gingiva might be slightly inflamed after an aggressive brushing or deficient hygiene. A local anti-inflammatory gel should be purchased, and a softer brush should be used, while waiting to see the practician or a dentist.
Finally, in case of an exceptionally more serious problem, it is recommended to call the following number (urgences dentaires de Paris – Paris dental urgencies):