Drs. Cardash, Ormanier, and Laufer, in their article ‘Observable deviation of the facial and anterior tooth midlines’ (J Prosthet Dent 2003;89:282-5) had five general dentists and five non dental observers view photographs of a series of patients to determine whether or not the facial and maxillary central incisor midlines deviated. They then scanned the photos into a computer and drew a facial midline using the medial angle of the eyes to base a perpendicular at the midpoint of the line. The perpendicular was then used to determine the facial midline.

Preliminary studies showed no difference between the dentists and non dental personnel in determining deviations of the midlines. The separate groups where then combined for the rest of the study. Within the limitations of this study, a majority of the ten observers noticed deviations of the anterior tooth midlines from facial midlines of greater than 2mm in magnified photographs. With deviations of less than 2mm, the detection rate decreased.