An analytical study on visuognosis for cognition of the facial midline

Abstract

Coincidence in dental and facial midlines is one of the goals of orthodontic treatment. The setting of a facial midline is important to achieve this treatment goal. However, there is no objective method for obtaining a facial midline, and the difference between the cognizance of orthodontists and laypersons is also uncertain. It is therefore important to specify a comparatively accurate facial midline. We defined a subjectively defermined facial midline as an imaginary facial midline, and we tried to elucidate the mechanism of the setting. We tried to limit the areas or structures of a face that we thought to be involved in the setting of an imaginary facial midline. The subjects of this study, 34 orthodontists with 3 years or more experience, were instracted to draw their own imaginary facial midlines in facial photostats of two adult Japanese with facial symmetry. As a result, we found the standard way by which orthodontists set an imaginary facial midline. The standard method is to set the imaginary facial midline so that it is as perpendicular as possible to a relatively horizontal line with attention given to both or either the middle point of the alares and/or the bottom point of the cupid bow as signposts.