System and method for automatic construction of orthodontic reference objects, such as the occlusal plane, arch form, and the local occlusal plane for a patient's teeth are disclosed. In accordance with an exemplary embodiment, a computer-implemented system and method for automatic construction of orthodontic reference objects comprises receiving three dimensional data for the teeth, setting an initial direction for a normal of the occlusal plane, determining tips for selected teeth, calculating a plane that matches the determined tip, and determining a new normal for the calculated plane.