This invention is a system, apparatus, and computer implemented method for arranging a computer model of teeth. According to one implementation, the method includes generating an arch form (482) representing an arrangement of teeth, placing a plurality of teeth (484A)-(484C) according to the arch form, determining a differential distance (488A) between each tooth, and its neighbors； and moving each tooth according to the differential distance. According to one implementation, the system includes a processor, a display device coupled to the processor, and a data storage device coupled to the processor, the data storage device storing instructions operable to cause the processor to generate an arch form (482) representing an arrangement of teeth, place a plurality of teeth (484A)-(484C) according to the arch form, determine a differential distance (488A) between each tooth, and its neighbors； move each tooth according to the differential distance, repeat the determining, and moving steps according to a function of at least one of the differential distances when the sum of differential distances for the plurality of teeth exceeds a predetermined threshold.
