Incidence of Straight, Sloped and Curved Midlines in Adult Humans

Author(s): Csillag Maria, Kakar Ajay

It has been traditionally documented and accepted that even though adult humans may have asymmetrical faces, a vertical straight facial midline line has always been used for aesthetics and functional dental rehabilitation. The standardly used landmarks for ascertaining the midline have been the glabella, the tip of the nose, the philtrum and the pogonion. In this study the pogonion has not been used because it is displaced in over 90% of individuals as per the Smylist® observation due to the mandibular rotation. First the horizontal lines were used to define the midline and then the midline plotted. This study has been conducted to ascertain the Smylist® tenet that all facial midlines are not necessarily straight. The tenet is that the midline can be straight, sloped to either side or curved to either side. A total of 100 subjects from Mumbai, India were photo documented in a straight face view in a standardized format and analysed for the type of midline using the Smylist® Aesthetic software. The results showed that the ratio of the three kinds of midlines were as 3.75 % for the straight midline, 55.55 % for the sloped midline and 40.7 % for the curved midline. It can be concluded that this study has shown that the incidence of the straight midline is only a small fraction in all the individuals in an Indian population which would be different from a European population.