1. A method for guiding scanning of an intraoral cavity of a patient, the method comprising: capturing one or more two-dimensional viewfinder images of one or more portions of the intraoral cavity of the patient, each of said one or more viewfinder images corresponding to a field of view of an intraoral scanner; scanning the one or more portions of the intraoral cavity with the intraoral scanner to generate one or more topography scans of the one or more portions of the intraoral cavity, the one or more topography scans corresponding to the one or more viewfinder images; capturing a two-dimensional viewfinder image of a portion of the intraoral cavity, the viewfinder image overlapping with the one or more viewfinder images; determining an area of overlap of the viewfinder image with the one or more viewfinder images; and displaying one or more indicators of the area of overlap on one or more locations of a display in order to provide guidance for positioning the field of view of the intraoral scanner, wherein said scanning the one or more portions of the intraoral cavity comprises focusing light onto the surface of the one or more portions of the intraoral cavity with confocal imaging optics and scanning the focused light through a range of focal depths, and wherein said confocal imaging optics share an optical path with viewfinder imaging optics for capturing said one or more two-dimensional viewfinder images.