An analytical study on the recognition of the facial midline by laypersons

Abstract

Coincidence in dental and facial midlines is one of the important goals of orthodontic treatment. However, there is no objective method for obtaining a facial midline. Moreover, the difference in recognition of a facial midline between orthodontists and laypersons is also uncertain. We defined a subjectively determined facial midline as an imaginary facial midline, and we clarified the setting mechanism of it by orthodontists. The purpose of this study is to analyze the difference in recognition of a facial midline between orthodontists and laypersons by conducting the same investigation to laypersons. 97 students of the faculty of liberal arts were chosen as the subject. They were instructed to find the middle point between two predetermined points (research 1) and to draw their own imaginary facial midline in photographs of two adult Japanese without obvious facial asymmetry (research 2). As a result of research 1, we found both groups recognized significantly accurate middle points if the distance was less than 60mm. From research 2, we also found that the standard method of both groups to set the imaginary facial midline was almost same. They both drew it as perpendicular as possible to relatively horizontal lines with attention to some points in the lower part of the nose and the upper lip, or just as an approximate line of those points.