Dental appliances for producing corrective movement in a subjects teeth include dental aligners which may be worn on a subjects teeth, gingiva or other region of the oral cavity. Described herein are dental appliances that include features that enhance the performance and comfort of the appliance, including features for preventing damage or wear on the appliance. Described herein are fluid-permeable aligners, wrinkled aligners, modular aligners, aligners of varying thickness, aligners of varying stiffness, snap-on aligners, textured aligners, aligners having multiple layers, and lateral correction aligners. Methods of making and using such aligners are also described.
