User interface having cross section control tool for digital orthodontics

A method comprising:

• displaying a graphical user interface (GUI) having a first region that includes a digital representation of at least a portion of a patient's dental arch within a three-dimensional (3D) environment and a second region that includes a digital representation of a second dental arch as a control image and at least one cross section control, wherein the cross section control is movable within the second region relative to the second dental arch to control a position of at least one cross section plane relative to the patient's dental arch within the first region, and wherein the cross section control comprises a moveable line within the second region, wherein the moveable line is positionable within the second region relative to the second dental arch based on input from a practitioner moving the moveable line in a horizontal direction relative to the second dental arch or moving the moveable line in a vertical direction relative to the second dental arch;
• rendering a cross section of the patient's dental arch based on the selected position of the cross section plane;
• in response to the input from the practitioner, automatically adjusting the position of the cross section plane within the 3D environment based on the position of the moveable line;
• and
• automatically updating the control image based on the selected position of the moveable line to provide an indication of a portion of the patient's dental arch that will not be rendered within the first region based on the position of the cross section plane.