Devices, systems, and methods for dental arch expansion

An orthodontic appliance system comprising:

• a first polymeric shell shaped to fit over a first arch of a patient's teeth and including a first plurality of teeth receiving cavities, wherein the first polymeric shell is shaped to impart a first arch expansion force onto a first tooth of one or more teeth of the first arch to move the one or more teeth of the first arch laterally outward from a midline of the first arch;
• a first occlusal feature extending from an outer occlusal surface of an occlusal wall of a first tooth receiving cavity of the first plurality of teeth receiving cavities, wherein the first tooth receiving cavity is shaped to accept the first tooth, the first occlusal feature configured to contact a second polymeric shell on an opposing arch of the patient's teeth and to impart first anti-tipping force onto the first tooth, the first anti-tipping force being in a direction to counteract a first tipping moment generated as a result of applying the first arch expansion force;
• and
• the second polymeric shell shaped to fit over the opposing arch of the patient's teeth and including a second plurality of teeth receiving cavities, wherein the second polymeric shell is shaped to impart a second arch expansion force onto a second tooth of one or more teeth of the opposing arch to move the one or more teeth of the opposing arch laterally outward from a midline of the opposing arch.

A method of expanding a first arch of patient's teeth, the method comprising:

• applying a first polymeric shell to the first arch to cause arch expansion to the first arch, the first polymeric shell including a plurality of teeth receiving cavities comprising a lingual wall, a buccal wall, and an occlusal wall extending between and connecting the lingual wall and the buccal wall, wherein the first polymeric shell is shaped to impart an arch expansion force onto a first tooth of one or more teeth of the patient to move the one or more teeth from a first position a first distance from a midline of the first arch to a second position a second distance from the midline of the first arch, the second distance being greater than the first distance, wherein the first polymeric shell has an occlusal feature located on an outer occlusal surface of an occlusal wall of a first tooth receiving cavity of the plurality of teeth receiving cavities, wherein the first tooth receiving cavity is shaped to accept the first tooth;
• and
• applying a second polymeric shell to a second arch of the patient's teeth, the second arch opposite the first arch, wherein the occlusal feature of the first polymeric shell is arranged to contact an outer occlusal surface of the second polymeric shell to impart an anti-tipping force onto the first tooth, the anti-tipping force being of a magnitude and direction to counteract a tipping moment generated at least in part due to the arch expansion force of the first polymeric shell.