A revised nose tip shape validation method for facial reconstruction based on CT data from a modern German population.

Abstract

Several methods aid with reconstructing features of the human nose, including angle, projection and width, but only one study by Davy-Jow et al. (2012) has focused on nose tip shape. The main finding was that the shape of the nasal bridge is consistent with the shape of the nose tip. The study also theorised that the method would not be suitable for snub (upturned) noses. Although promising, further investigation with a larger sample of different origin would be of benefit. In addition, grouping samples into upturned, horizontal and downturned nose tips could reveal the need for a difference in the applied method. The approach has been recreated with a larger sample size (N=103 versus N=25) derived from a modern German population. Based on soft tissue models, the individuals were firstly grouped into three categories; upturned, horizontal, and downturned noses. Computed Tomography (CT) data allowed the simultaneous visualisation of both skull and (semi-transparent) facial surfaces. Each head was viewed frontally in the Frankfurt Horizontal Plane (FHP), and then tilted back until the nasal tip superimposed the nasal bridge, with the angle of tilt measured from the FHP. The results show that the angle of tilt is significantly different for upturned, horizontal, and downturned noses, but that it can be equally applied to all three groups. The mean angle was 44° for upturned noses, 51° for horizontal, and 56° for downturned. Error studies suggest a very high accuracy and repeatability with intra-class correlation coefficients of 0.991 (inter-observer error) and 0.972 (intra-observer error) respectively.