The “Transograph” was invented by Harry L. Page of Valparaiso , Indiana . Page, an engineer, had been investigating various aspects of dentistry in which he was interested since the 1930's. In the 1950's, he became keenly interested in the study of mandibular movement and articulator design. The “Transograph” was based on Page's concepts of anatomy, occlusion and mandibular movement. Page did not believe in a transverse horizontal axis, so he split the axis by dividing the upper member into two separate parts. “Transographics” suggests that each condyle rotates around different axes and this is provided by means of the “Spit-axis”; that is, no solid connection between the condylar elements. The condylar controls are positioned in the instrument anatomically and can be at different horizontal and vertical planes. Consequently, the right and left condylar controls were only joined by the mounted maxillary cast. By using a pin-in –sleeve rather than the ball type condylar controls, the Transograph is claimed to be able to record all gross and functional envelopes of motion by using a series of occlusal records at progressively wider openings. The axis locator was employed as a transfer bow and actually became the lower member of the instrument. The angle of the lower member is set to the mandibular angle to insure the correct occlusal curve. The most unusual feature of the “Transograph” was its flexibility which “simulated the flexure of the mandible as it compensates for the split axis.
Dr. Edgar N. Starcke's articles in the Journal of Prosthodontics have more information on the history of articulators.