Hi Loulou
As mentioned, having braces would not be classed as a medical condition, just as it is not in the UK, unless there are other maxilofacial issues, and as for the jaw dislocation this will be covered in a
hopital with no problem, i worked and lived in paris for two years, so i can vouch that the dentists there are cheaper pro rata than in the Uk. Just make sure you have the EHIC card.. then if there are issues, you need to firstly find a local doctor in the region you are staying, who will charge approx 10 euro for the consultation, and if cannot help, will refer you on to a hopital or infirmarie, where they will be able to help..French doctors are much better than UK ones ( did i tell you all some of my relations are french? plus i did part of my training in France).
By the way which part are you in?... I will be working at an emergency infirmarie in Taize/Amgeuny/Macon over the summer, and until 3rd wk of Sept. can't wait
Bye for now
Jon
XXX