The big majority of orthodontics in Britain is carried out with fixed appliances which achieve excellent alignment of the teeth but several scientific papers have suggested the possibility of adverse facial changes (Battagel 1996). I think orthodontists are embarrassed about this but believe that by avoiding discussing the subject, the public will not be worried.
The father of the girl shown below was a medical doctor and asked for non-extraction treatment for his daughter hoping this would avoid damage. After a year of retractive Headgear there was little change and she then had 4 teeth extracted. After another year the orthodontist said she would need jaw surgery. The picture below shows the change to her face at that point.
The next patient (below) received a nice improvement from Biobloc Orthotropic treatment but then decided to have the alignment improved with fixed appliance. See the vertical growth that followed.