Measurements of dental cast profile and three-dimensional tooth movement during orthodontic treatment

A system developed for measuring three-dimensional profiles of dental casts and three-dimensional tooth movement during orthodontic treatment is described. The profile measurement is based on a triangulation method which detects a laser spot on a cast using an image sensor. The system is computer-controlled and designed to achieve the depth and lateral resolutions of 0.05 mm and 0.1 mm, respectively, within a depth range of 25 mm. The movements of teeth, including rotations, were obtained by means of three-dimensional registration of tooth profiles using a computer between casts that were serially taken at different stages of the treatment. Measurements on patients over periods of 70 to 190 days revealed that this technique is capable of quantifying the difference in movements due to orthodontic therapeutics.