Simple System to Record Jaw Movements by a Home Digital Camcorder

Purpose: Systems of recording jaw movements that are used in prosthodontics and orthodontics are too expensive and complicated for daily clinical diagnosis. This pilot study presents the development of a simple system using a camcorder and motion-capturing software. Materials and Methods: Markers to detect jaw movement were attached to the mandibular incisors of a subject. A mirror was assembled beside the subject's face to detect anteroposterior movement. Jaw movements were recorded by a home digital camcorder. Movements of the markers were analyzed by motion-capturing software and transferred to 3-D data. The results were compared with those of a conventional system. To examine the accuracy of the measurements, the markers were placed on a computer-controlled x-y working stage and displaced. The positions of the markers were measured and analyzed, then compared with the true values indicated by the x-y working stage. Results: The trajectories of the mandibular incisors recorded by the new system were very similar to those of the conventional system. On measurement accuracy, the mean differences between the measured and true values of the vertical and transverse movements were 0.07 mm (SD 0.03) and 0.06 mm (SD 0.04), respectively. On anteroposterior movement, the difference was 0.11 mm (SD 0.05). Conclusion: This new system can be useful for simple recording of jaw movements with satisfactory accuracy.