Abstract: A method of providing a symmetrically proportional gap-free smile including a computer product for carrying out the method. A method requires measurements of the lateral arch length, the lateral width of each tooth from the upper left canine to the upper right canine, and the lateral width of any gaps between the measured teeth. A proportional lateral width of each tooth in the measured lateral arch is calculated so that the lateral incisor widths are equal to 61% to 90% of the width of the central incisor, and the canine widths are equal to 80% to 99% of the width of the central incisor. The lateral width of the teeth in the measured lateral arch is modified to provide the calculated proportional tooth lateral widths extending along the measured lateral arch length without gaps between the teeth.