Description of a photoelastic coating technique to describe surface strain of a dog skull loaded in vitro.

There are several methods of determining strain in the facial skeleton on loading in vitro. This article describes an alternative photoelastic coating technique adapted from the commonly accepted method used by engineers to study surface strains in objects. In applying this method to the stomatognathic system, because the masticatory apparatus is loaded by muscular contraction an opposite reaction load should be distributed throughout the skeletal structure. This load distribution should slightly deform the bones to which the muscles of mastication are attached. An understanding of the resulting strain generated in the facial skeleton is important because strain distribution on loading reflects how the loads applied during mastication are partially dissipated. Preliminary descriptive results are presented, suggesting that anatomic structures influence the distribution of strain on loading. The technique described should allow in vitro investigation of the mechanical environment into which osseointegrated implants are placed and may aid in understanding their behavior.