Recording mandibular movement: technical and clinical limitations of the Sirognathograph.

It is essential to know the limitations of any equipment used for research or clinical purposes. Clinical electronic equipment is commonly sold for "black box" use without specification of artifacts. This study tested the technical and clinical limitations of the Sirognathograph, which is a device used for recording mandibular movement. From a technical point of view, the Sirognathograph's slow sampling speed and sample artifacts have been shown to be the system's main limitations; however, it was possible to eliminate sampling artifacts by using a customized pulse generator and software for controlled data acquisition. Clinically, the Sirognathograph appears to have some inherent limitations in its accuracy. The effect of cranial movements during mastication can cause a baseline drift with consequent errors in the recording of mandibular position. This problem was controlled in this study by using a headband to stabilize the cranial movements during mastication. Also, the spatial relationships between the aerial and both the cranial base and the magnet were found to be critical for repeatability of the recordings.