Otic axis locator: closing the accuracy gap in cephalometrics and cast mounting.

摘要

An overview is presented of a new technique to improve the accuracy and reproducibility of earpost-dependent orientation in procedures such as cephalometric radiography and cast mounting, using a custom-molded ear canal insert to provide a stable fitted socket for more exact earpost fit. This is especially valuable in follow-up treatment and serial studies because the insert can be filed for future use on the same patient to provide identical positioning in successive registrations. Cephalometric radiography is further enhanced by the addition of a radiopaque x-ray marker deep in the canal, otherwise inaccessible, close to the bony ear canal (anatomical porion) and the mandibular condyle. This marker is also visible in all 3 cephalometric views-lateral, frontal (posteroanterior) and coronal (submental-vertex)-providing an exact common horizontal axis (Otic axis) for a three-dimensional Cartesian coordinate system of measurement.