Aligners work by putting forces on teeth in very small doses as dictated by trays resembling bleaching trays. Each tray can move a tooth an average of 0.2 mm and can also move individual teeth.
A computer CAD/CAM system visualizes the planned movement and figures out how many aligners would be needed to achieve the goal. A series of models are created, and these are used to create a series of trays, or aligners. each one is trimmed and polished and sent to the dentist or orthodontist, all at once.
Normally, 3 aligners at a time are dispensed, each one worn for 2 weeks. On average every 6 weeks the patient would return to the office and the doctor would monitor the progress, adjust the teeth as necessary, and dispense another 3 trays.
While the system allows much more precision in planning, teeth and bone do not always react the way the computer says they should, so Invisalign is not a magic pill that works for all cases.
