Dynamics of human teeth in function by means of double pulsed holography; an experimental investigation

Investigation in vivo of small deformation and mobility processes in the masticatory system of man has been until now a very intricate problem. Mechanical as well as noncontact methods have been utilized earlier in order to record the mobility pattern of teeth and prosthodontic appliances. In this paper holographic interferometry will be presented as a solution of some odontological measurement problems. The method was first tested in a simulator arrangement and then used in a number of clinical experiments. A special, totally reflecting paint was used for surface preparation prior to holography. A Q-switched double-pulsed ruby laser was combined with an electronic subminiature force sensor for pulse triggering, which was actuated by the masticatory force of the patient. Force increases and pulse positions were registered synchronously on the screen of an oscilloscope. The applied force exerted by the patient's masticatory muscles could thus be defined according to its point of application, direction, amplitude, and duration. The corresponding surface deformation was evaluated by means of a synchronized, double-exposed hologram. Conclusions could be drawn regarding the relative and absolute mobility of the teeth and related structures of the holographed jaw section.