Methods and systems for fabricating dental appliances with integrally formed arch expander

A system comprising:

• one or more hardware processors;
• and
• a memory comprising instructions that, when executed by the one or more hardware processors,
• cause the system to perform operations comprising:
• determining an appliance geometry for a dental appliance, wherein the appliance geometry comprises:
• a first region representing a first shell portion having a first set of cavities configured to receive one or more teeth at a first side of a dental arch of a patient,
• a second region representing a second shell portion having a second set of cavities configured to receive one or more teeth at a second side of the dental arch, and
• a third region representing an integrally formed arch expander configured to exert forces to increase a width of the dental arch, the integrally formed arch expander comprising:
• a first end coupled to the first shell portion,
• a second end coupled to the second shell portion, and
• an intermediate portion extending between the first and second ends, wherein the intermediate portion is spaced apart from the first shell portion and the second shell portion;
• generating fabrication instructions for fabricating the dental appliance having the appliance geometry via an additive manufacturing process;
• and
• using the fabrication instructions to instruct a fabrication system to fabricate the dental appliance having the appliance geometry via the additive manufacturing process, wherein the using the fabrication instructions comprises:
• fabricating the first shell portion and, the second shell portion from a sequential plurality of first polymer layers, and
• fabricating the integrally formed arch expander from a sequential plurality of second polymer layers,
• wherein the sequential plurality of second polymer layers of the integrally formed arch expander are fabricated concurrently with the sequential plurality of first polymer layers of the first shell portion and the second shell portion.