Methods and systems for determining a dental treatment difficulty in digital treatment planning

A system comprising:

• one or more processors;
• and
• memory coupled to the one or more processors, the memory configured to store computer-program instructions that, when executed by the one or more processors, cause the system to execute a method comprising:
• processing a scan of a patient's dentition to derive a virtual three-dimensional (3D) model of the patient's dentition, wherein the virtual 3D model corresponds to an initial dental model of a patient's arch including a first tooth in a first initial position and a second tooth in a second initial position;
• generating a digital treatment plan for moving the patient's dentition from the initial dental model toward a target dental model, wherein the first tooth moves from the first initial position toward a first subsequent position and the second tooth moves from the second initial position toward a second subsequent position;
• determining changes in position of the first and second teeth between the initial and target dental models relative to an arch line of the initial dental model by:
• projecting a first distance between the first initial position of the first tooth and the first subsequent position of the first tooth onto the arch line, and
• projecting a second distance between the second initial position of the second tooth and the second subsequent position of the second tooth onto the arch line;
• calculating an average change in position using the first change in position of the first tooth and the second change in position of the second tooth;
• determining a treatment difficulty of anterior-posterior (A-P) correction by comparing the calculated average change in position to one or more threshold changes in position;
• and
• adjusting the digital treatment plan when the average change in position is greater than at least one of the one or more threshold changes in position.