User blog comment:BoaHankokku/Ain's Devil Fruit/@comment-4493594-20120820221629

It's pretty simple: Bonney's aging and de-aging is a process of turning someone to either a child or an old person. Ain's ability is returning something to a former state.

Let's say someone breaks a door. Ain could use her ability to de-break the door, since it was not broken previously. Now we do not know how strong that DF is but in theory she could use it to heal people's injuries by returning them to a state when they were not damaged.