Aligners are designed to apply desired forces on the tooth. The shape of aligners to produce such forces is not necessarily the same as the shape of the tooth. The movement required for each individual tooth, mechanical principles to accomplish this movement and the aligner shape are determined cad software. The aligner shape is altered via pressure points or power ridges in order to apply the desired forces. Pressure points lead to more difficult up righting and intrusion movements, whereas power ridges control axial root movements and torque.

Clear aligners provide an esthetic and comfortable option to conventional fixed mechanics. Obtaining periodontal health is easier in patients treated with clear aligners and less white spot lesions develop during the treatment. Clear aligners can be used in mild to moderate crowding cases but caution must be exercised in complex cases.