Orthodontic progress tracking using coarse to fine 3d models

A method comprising:

• identifying a stage of treatment in an orthodontic treatment plan at which to assess the treatment plan for a corrective action, wherein the treatment plan includes moving at least one tooth of a patient's teeth along an initial treatment path from an initial position towards a final position;
• obtaining a plan model of the patient's teeth based on the treatment plan, the plan model providing a planned arrangement of the patient's teeth at the identified stage of the treatment plan;
• obtaining a tracking model of the patient's teeth, the tracking model representing an actual arrangement of the patient's teeth at the identified stage of the treatment plan;
• generating a comparison of one or more anatomical reference shapes and one or more surface features on the plan model with corresponding one or more anatomical reference shapes and one or more surface features on the tracking model using a coarse to fine volume 3D array to represent one or both of the plan model and the tracking model, wherein the coarse to fine volume 3D array includes a plurality of coarse volumes, each coarse volume including a plurality of fine volumes, wherein each of the coarse and fine volumes includes a reference to a closest vertex of the tracking model;
• detecting one or more positional differences between the anatomical reference shapes and surface features of the plan model and the corresponding anatomical reference shapes and surface features of the tracking model based on the comparison and using the coarse to fine volume 3D array;
• generating a modified treatment plan based on the one or more detected positional differences.

A method comprising:

• obtaining a plan model of a patient's teeth based on an orthodontic treatment plan, the plan model providing a planned arrangement of the patient's teeth at an intermediate stage of the treatment plan;
• obtaining a tracking model of the patient's teeth, the tracking model representing an actual arrangement of the patient's teeth at the intermediate stage of the treatment plan;
• generating a comparison of one or more anatomical reference shapes and one or more surface features on the plan model with corresponding one or more anatomical reference shapes and one or more surface features on the tracking model using a coarse to fine volume 3D array to represent one or both of the plan model and the tracking model, wherein the coarse to fine volume 3D array includes a plurality of coarse volumes, each coarse volume including a plurality of fine volumes, wherein each of the coarse and fine volumes includes a reference to a closest vertex of the tracking model;
• detecting one or more positional differences between the anatomical reference shapes and surface features of the plan model and the corresponding anatomical reference shapes and surface features of the tracking model based on the comparison and using the coarse to fine volume 3D array;
• generating a modified treatment plan based on the one or more detected positional differences;
• and
• fabricating a dental appliance based on the modified treatment plan.