My wife has toenail growing over existing toenail on her big toe, There is no infection or damage to the nail?

What Causes this? she has no pain in the Nail, or dis colloring.My wife has toenail growing over existing toenail on her big toe, There is no infection or damage to the nail?
That is an abnormal condition. She needs to see a podiatrist to have that examined before the second nail keeps growing over the original one and eventually can make it harder to walk.My wife has toenail growing over existing toenail on her big toe, There is no infection or damage to the nail?
she should go to a foot doctor, a podiatrist . because no offense, but that's freaky weird!