The History of Occlusion and Articulators

Abstract

The history of occlusal theories can be traced with the history of the articulators. The study of mandibular movements, especially that of condylar movements, is central to the history of oc clusal theories. The purpose of this paper is to examine the study of condylar movements and the evolution of the articulatorʼs condylar path design. In this review, I exclude the interpretations by later generations and reconstruct the perspectives of the time. This in turn reveals how far the conventional history of the scholarship in question has deviated from the original. First, W. G. A. Bonwill left as his legacy an anatomical articulator with two articulations like the human temporomandibular joint (1864) as a result of his pursuit for principle system of occlusion based on objective observational data. In 1897, Walker developed a physiological ar ticulator with adjustable tilt and anteroposterior movements of the working condyle to reproduce the individual differences in human occlusion (1897), and he learned about Luceʼs precise mea surement of condylar movements (1889); but he then went beyond that to reveal the relationship between condylar movements and occlusal surface morphology. Walker devised a mechanism for anteroposterior adjustment of the working condyle by placing a fulcrum on the intercondylar axis (wippunkt), though is largely neglected today (this mechanism is todayʼs regulation of intercondy lar distance). Gysi inherited and improved on Walkerʼs articulator with the Wippunkt articulator (1908), which was able to adjust the condylar path inclination and anteroposterior movements of working condyle, but a paper on Bennett movement published in the same year pointed out that this could not be reproduced. After four years of hard work, Gysi developed an Adaptable Ar ticulator that could reproduce Bennett movement (1912), and then introduced the Gysi Symplex (1914), by averaging values of Adaptable Articulator. In the meantime, Bennett stated: “The condylar movements differ between the lateral move ment with the teeth contact or without teeth contact. Furthermore, the lateral excursion with the teeth contact moves the working condyle not only laterally but also slightly downwardly”. This discovery was for the large part ignored by the prosthodontic societies and is wrongly interpreted today as a mere shift in the direction of movement. Meanwhile, Gysiʼs Adaptable Articulator has a lower reputation in the United States, and most of the literature wrongly refers to it as Wip punkt Articulator, and in effect, it is settled as Wippunkt Articulator even in Japan. Later, Gysi developed TRUBYTE Articulator (1926), a condylar type, with independent mechanism of Ben nett movement and with the anteroposterior regulation of the working condyle by the incisal guidance. TRUBYTE Articulator influenced later developments of Hanau University Articulator and Stuart Articulator.