A reevaluation of the axis-orbital plane and the use of orbitale in a facebow transfer record.

A fundamental assumption in prosthetic dentistry is that the axis-orbital plane usually will be parallel to the reference horizontal. Most articulator systems have incorporated this concept into their designs and use orbitale as the anterior reference point for transferring the vertical position of the maxillae to the articulator. The position of the maxillary cast is expected to be in the same vertical position as the maxillae with the subject's head oriented in the esthetic reference position. However, the use of orbitale in conjunction with an articulator whose design assumption places the axis and orbital indicator parallel to the horizontal reference will result in a substantial mounting error. This article examines the cause and correction of the mounting error that results from the use of orbitale as the anterior reference point of a facebow transfer record made to an axis-orbital designed articulator.