The described method uses "invisible ink" and ultraviolet (UV) illumination to produce a high contrast image of the incisal edges of the teeth on the model. The advantages of this new method are that it is nondestructive, does not leave visible marks on the models, reduces operator subjectivity in selecting the portions of the anterior teeth to be highlighted, and lends itself to easy construction of overlays by using computer image-processing software such as Adobe Photoshop and ImageJ. It is possible to mark different areas of a stone cast with different inks; and, depending on the illumination wavelength used, highlight different areas of the same cast in different photographs. Once an image has been made with the incisal edges of the anterior teeth highlighted by this technique, the computer software is used to select the areas for hollow volume tracing. Fiber-tipped markers containing "invisible ink" that fluoresces under ultraviolet illumination were obtained from LDP LLC. The markers evaluated were the UVInkPenLg, which contains an isopropyl-alcohol-based ink that glows bluish-white under 395 nm UV illumination, and the UVInkPenYL, which has a ketone-based ink that glows greenish-yellow under 365 nm illumination. A digital camera was used to produce images of the highlighted incisal edges, because transferring digital images to the computer for analysis is much easier and quicker than having to scan conventional film negatives or photographic prints. 5 figures and 3 references