Very interesting subject !
Like many of you, I love when orthodontic treatments last during more than the classical 2 years long.
It's pretty rare when the treatments last longer. Sometimes, it can happen everywhere in the world for 2 and a half or 3 years, especially when there is a surgery.
But I see sometimes ladies that keep their braces during 4, 5 or 6 years, maybe more. It's nearly always Brasilian women.
The ten years and a half mentionned above seem to be a record.
I'm pretty sure that when the treatment last more than 4 years, that's the patient who wants to keep the braces, like this woman. I think in that case, the braces are more viewed as an aesthetic or a fashionable object than a medical device.
It would be interested to check if a treatment can last that kind of duration for real medical purpose.
