A biomechanical study of the human facial skeleton by means of strain-sensitive lacquer.

K U n t s c h e r (1934) employed the strain-sensitive lacquer for the first time to investigate the mechanical characteristics of bones. This technique was then used by G u r d j i a n and Lissner (1945), Evans and Lissner (1948), Evans, Lissner and Pedersen (1948), Evans and Lissner (1955), Evans and G o f f (1957), and Endo (1961) in their biomechanical studies on the bone. The technique of strain-sensitive lacquer, i.e., brittle coat, such as STRESSCOAT (Magnaflux Corp.) is one of the useful methods to clarify the orientation of the axes of principal strain or stress in the intact bone. It has been said that the form and the structure of the facia' skeleton are closely related to the mechanical function of the masticatory apparatus, and consequently to the distribution of stresses produced by the latter. Accordingly, there is a need at first for an analysis of those stresses in the facial skeleton in order to study the above problem. The present paper deals with the analysis of strains due to the above stresses by means of strain-sensitive lacquer. For the analysis, forces were applied to macerated skulls under the approximately same condition as that of the biting action, and the axes of principal strains in the facial skeleton were visualized by the crack of the lacquer. The results obtained from the present experiment were compared with those obtained from the experiment by means of wire strain gauge made by the present author (1964, 1965, 1966).