The influence of sex, age and body mass index on facial soft tissue depths

Facial soft tissue depth charts are used in the majority of forensic facial approximation methods. In the past, based on the multitude of available soft tissue depth charts, a number of hypotheses were advanced concerning the impact of sex, BMI and age on the depth of tissues. In this study, for the first time, a multivariate analysis was performed on a large-scale study on Caucasian adults to determine the "real" impact of these attributes. The calculation of a robust multiple linear regression of soft tissue thickness versus BMI, age and sex for each landmark separately, allowed us to study the impact from a statistical as well as practical point of view. Former findings were re-evaluated. Additionally, the results confirm the dominant role of BMI in the alterations of facial soft tissue thickness. However, excluding age and sex from the equation should be considered with care and can certainly not be applied to all landmarks. Finally, the regression equation allows increase in the specificity of tissue depths used in real cases by offering practitioners the possibility of calculating individual tissue depths.