IF brackets on upper centrals are debonded, what can happen?
Answer) upper centrals move buccaly until they touches upper wires
You may think tooth may not move when bracket came off because force is not applied from the arch wire. But most of the time, it moves. While force from the wire is not applied, the tooth is still in oral environment. There is tongue and cheek.
Teeth position is stabilized after achieving equilibrium between pressures from soft tissue.