1. An image viewing system comprising: a source of intraoral dental images; a computer having a processor and a user interface module, the user interface module configured to generate a graphical user interface, the graphical user interface having a first window in which at least one intraoral dental image from the source of intraoral dental images is displayed; and a screen connected to the computer and configured to display the graphical user interface; wherein, in response to at least one user input, the graphical user interface is configured to generate an image-navigation map and to display the image-navigation map in a foreground of the first window and the at least one intraoral dental image from the source of intraoral dental images in a background of the first window, wherein the image-navigation map is overlaid upon the at least one intraoral dental image, the image-navigation map including one or more thumbnail images of at least one of the intraoral dental images from the source of intraoral dental images, each of the thumbnail images indicating a predefined region of a patient's dentition, and wherein the thumbnail images are arranged to correspond to the patient's dentition.