Smoking-related variation in facial soft tissue thickness assessed by ultrasound: forensic implications for facial analysis

Abstract

Background

Facial soft tissue thickness (FSTT) represents a key parameter in forensic facial reconstruction and human identification, reflecting both biological and behavioral influences. This pilot cross-sectional study examined the impact of body mass index, age and smoking status on FSTT in a Slovak adult population, with emphasis on sex-specific variations.

Methods

A total of 246 participants (176 females, 70 males) were measured using B-mode ultrasonography across eight midline facial landmarks and eight paired bilateral landmarks. Statistical analyses included non-parametric tests, Spearman rank correlation and general linear models with BMI and age as covariates.

Results

Sex-specific patterns were identified. In females, BMI was the dominant predictor, showing medium to large effects across most landmarks. Age contributed modestly to variation, particularly in the lower face. Smoking related differences were localized, rather than consistent across facial landmarks. Female conventional smokers showed lower FSTT values than non-smokers at the left fossa canina landmark (p = 0.046). In males, age showed a stronger and more consistent association with FSTT than BMI, with age-related variation most evident in midfacial and mandibular regions. Direct comparison between smokers and non-smokers in males revealed no significant differences in FSTT at any landmark. Overall smoking status was not consistently associated with FSTT.

Conclusions

The findings highlight sex specific and anatomical variability in FSTT and provide population specific data relevant for forensic facial reconstruction. Larger and more balanced samples are needed to confirm these preliminary associations.