A lot of health care workers in rural and remote Australia are from overseas. They may be traveling or working rurally in order to gain citizenship (you must work in rural areas in order to emigrate to Australia as the positions are hard to fill). Perhaps the dentist trained in Europe? And the European style dental work gave LE the idea Karlie was foreign?
It was actually the isotrope (?) analysis that indicated she was possibly from Eastern Europe. Karlie had "western style dentistry" consistent with most people in Australia.
http://www.canberratimes.com.au/act-news/somebodys-daughter-20120205-1t8r9.html
I've read the above in other articles before too, but they are hard to find now as they are buried under all the new ones. I think LE was just grasping at straws trying to identity her and were turning to all kinds of forensics, including less reliable ones such as the facial reconstruction.