The precision of presurgical orthodontic diagnostic protocol plays a key role for the success of orthognathic surgery. Recently, the introduction of cone beam computed tomography and the development of digital technologies led to the possibility to create new virtual protocols of diagnostic protocol. The purposes of this study were to describe the virtual presurgical orthodontic diagnostic protocol experimented by the Orthodontics Department of the University of Milan and to assess its reliability by comparing it with the nonvirtual protocol. The study sample was a group of 18 adult patients who required surgical correction of skeletal asymmetric class II or III malocclusion: 9 of them were subjected to the virtual diagnostic protocol, whereas the other 9 were subjected to the traditional one. A comparison between the 2 methods was carried out by evaluating the degree of the discrepancy between setup and presurgical models in both groups. The values of maximum positive deviation, maximum negative deviation, mean deviation, and standard deviation that characterize the points of the superimpositions were considered. An optimal superimposition (>75%) between the scanning of the setup and presurgical models was obtained for all subjects except for 2 patients with asymmetry. The analysis of the punctual deviation variables did not show statistically significant differences between the techniques. The study suggested a high precision for both diagnostic protocols, and the reliability of the 2 methods is comparable. However, the virtual protocol has several advantages such as quantity of information obtainable, repeatability, and speed of execution.
