When constant force is applied to a tooth, it causes bone loss at the point where the bone is being pressed. Bone regeneration occurs on the opposite side to fill the space created by the tooth movement. This process begins after 48-72 hours. 4 hours after the pressure is removed (the splint is not worn), this activity stops. Therefore, it is important to wear the clear tray 22 hours a day. The first few days of a new aligner are crucial. This is when the aligner is strongest. Bone regeneration takes longer than bone resorption.