Systems for fabricating orthodontic appliances with power arms

A system for fabricating a dental appliance, the system comprising:

• one or more processors;
• and
• a memory operably coupled to the one or more processors and storing instructions that, when executed by the one or more processors, cause the system to perform operations comprising:
• determining an appliance geometry for a dental appliance including a shell configured to move a patient's teeth from an initial arrangement toward a target arrangement, wherein the appliance geometry comprises:
• a first power arm having a first connection point for connecting to the shell,
• a second power arm having a second connection point for connecting to the shell or to a tooth,
• an elongate connecting structure coupled to the first and second power arms, and
• an elongate counter-force connector coupled to the first power arm and extending toward the second power arm,
• wherein the elongate connecting structure and the elongate counter-force connector are coupled to the first power arm at respective locations separate from the first connection point, and
• wherein the elongate connecting structure is coupled to the second power arm at a location separate from the second connection point;
• and
• a fabrication system configured to directly fabricate the dental appliance comprising the appliance geometry.