A method of recording condylar movements and joint sounds

A commercial tracking system has been adapted within the University of Melbourne, which is designed to track the movement of infra-red light emitting diodes (LEDs). The movement of the diodes was recorded by photosensimetric recording devices, and sent to a data recorder, then to a differential amplifier, and the signal stored on magnetic tape, or viewed on a cathode ray oscilloscope, or plotted on a chart plotter or an X-Y plotter. The equipment was used to track the movement of LEDs, which were secured to a lower arch face bow, which was in turn secured to the teeth via a universal joint, and an acrylic clutch. A method was established in a preliminary study, enabling recording of condylar movements in the sagittal plane, and results were presented for four subjects. Subsequently, condylar movements and joint sounds were recorded concurrently for two of these four subjects.