Thank you for your question and welcome to Just Answer.
The first thing you need to make sure of is that the X-ray you are referring to was taken at the proper angle in relationship to the film. If the beam of the Xray is not parallel to the film, then the images can be artificially lengthened or shortened. The following article shows how easy it is to have an improperly taken X-ray fool you into thinking the roots are resorbed:
It seems quite odd that ALL of her teeth have become shorter.
With that in mind, the roots of teeth that have been moved too quickly by orthodontics will start to resorb the roots, making them shorter. This usually only happens to one or a few teeth. At age 10 and a half, I would assume she still has some baby teeth in place and the permanent teeth that have not erupted will not be affected.
The severity of the situation depends on how much of the root has dissolved away. If a quarter to a third of the root has resorbed, then there won't be much of a consequence, unless as an adult your daughter gets periodontal disease, which dissolves the bone away from the teeth. With short roots, her teeth would become loose much sooner than someone who had normal sized roots. If she has lost a half of the root or more, she runs the risk of her teeth not being able to withstand strong forces of chewing and can get prematurely loose teeth and potential tooth loss as an adult.
I hope this answers your question. If you would like to discuss this further or have any additional questions, please reply to my answer and I will get right back to you.
Sincerely, XXXXX XXXXX DDS
Thank you for the additional information. Obviously and unfortunately we are not dealing with an error on the X-ray technique in this case. Root shortening used to be blamed completely on over aggressive tooth movement during orthodontic treatment but recent studies have found a genetic predisposition for some individuals to over react to even normal orthodontic forces. See:
Your daughters braces don't necessarily have to come off, but treatment will probably have to be slowed down significantly. If no further adjustments to the wires and elastics are made, the teeth remain in their current position and she can go through a rest period. Future treatment will have to be made slowly and carefully with frequent X-ray monitoring to check on the length of the roots. I hope this helps.