Image based dentition tracking

A system comprising:

• one or more processors;
• and
• memory storing computer program instructions that, when executed by the one or more processors, cause the system to execute a computer-implemented method comprising:
• identifying a stage of a treatment plan administered to a person's dentition;
• receiving a two-dimensional photo of the person's dentition corresponding to the stage of the treatment plan;
• gathering a three-dimensional (3D) model of the person's dentition corresponding to the stage of the treatment plan;
• projecting attributes of the 3D model of the person's dentition onto an image plane to get a projected representation of the person's dentition at the stage of the treatment plan;
• comparing a position of one or more teeth of the person's dentition in the two-dimensional photo to the projected representation of the person's dentition to derive two-dimensional error image representing the comparison;
• and
• analyzing the two-dimensional error image for discrepancies, wherein analyzing includes determining a distance between corresponding edges in the error image, and wherein the discrepancies represent one or more deviations of the person's dentition from the stage of the treatment plan.