Assessing zygomatic shape and size for estimating sex and ancestry in a South African sample

Developmental changes of the facial skeleton from birth to 18 years within a South African cohort (A computed tomography study)

Skeletal remains are often found on a crime scene in which a forensic anthropologist is then consulted to create a biological profile, which includes the estimation of age, sex, ancestry and stature. The viscerocranium plays an important role in the formation of a biological profile. However, to utilise the viscerocranium for age estimation, population specific normative data and knowledge of the development of the viscerocranium is required. Therefore, this study aimed to investigate the developmental changes from birth to 18 years of age of the facial skeleton of individuals from a South African cohort. This study comprised of 239 computed tomography (CT) scans (128 males; 111 females). The viscerocranium was subdivided into five regions viz.: orbital, nasal, midfacial, maxillary and mandibular. The linear parameters in each region were correlated to age to identify the developmental growth patterns of the viscerocranial regions according to male and female. The measurements which displayed the highest correlations with age were used to develop formulas which could be used for age estimation. The results of this study showed that the measurements in the orbital, midfacial, maxillary and mandibular regions experienced rapid growth between 0 and 5 years of age, with the nasal region increasing steadily over time. It was noted that males displayed overall larger measurements than females except for the anterior interorbital distance and both right and left zygomatic arch lengths (ZAL). Although only the left orbital height, nasal aperture height and mandible width displayed statistically significant size differences according to sex (p ≤ 0.05). The measurements which showed the highest correlations to age were the zygomatic arch distance (r = 0.8842, p < 0.001), ZAL (right: r = 0.8929, p < 0.001; left: r = 0.8656, p < 0.001) and the mandible width (r = 0.8444, p < 0.001). Formulas were derived for the measurements that could be used to forensically estimate age within a subadult cohort.