Developmental changes of the facial skeleton from birth to 18 years within a South African cohort: a computed tomography study.

Abstract

Introduction: The facial skeleton or viscerocranium has been recently noted as a method for age estimation as its development is influenced not only by the developing paranasal air sinuses and tooth eruption, but also the individual’s ancestry particularly population specific normative data. This study aimed to investigate the developmental changes of the facial skeleton in males and females from birth to 18 years within the South African population with African ancestry to estimate age. The facial skeleton was assessed according to five regions viz: - orbital, nasal, midfacial, maxillary and mandibular. Methods and materials: A retrospective study which consisted of 239 computed tomography (CT) scans of subadult individuals (0–18 years of age) of African ancestry (128 males; 111 females) was conducted. The scans were obtained from an online server utilised by a private medical facility in the eThekwini Muncipality. The DICOM images were viewed from an online Picture Archiving and Communication Systems server using Infinitt software (version 5.0.1.1) which is the standard software used by the practitioners. Linear parameters in the horizontal, sagittal, and vertical planes assessed the development of the viscerocranial regions. Results: a) Development: Most of the viscerocranial regions experienced a rapid increase in growth between 0–5 years of age viz: orbital (orbital height and width: 0–5 years; lateral orbital wall distance: 0–3.75 years), midfacial (zygomatic arch distance: 0–3.75 years), nasal (aperture height and width: 0–5 years); maxilla (length: 0–3.75 years), mandibular (mandible width: 0–5 years). Thereafter growth continued to increase at a slower rate in the orbital width (0.61–0.8 mm/year in females; 0.56–0.76 mm/year in males), lateral orbital wall distance (1.1 mm/year in females; 1 mm/year in males), zygomatic arch distance (1.6 mm/year in females; 1.8 mm/year in males), nasal aperture width (0.45 mm/year in females; 0.4 mm/year in males) and height (0.63 mm/year in females; 0.77 mm/year in males), maxillary length (0.7 mm/year in females; 0.81 mm/year in males), mandible width (1.1 mm/year in females; 1.5 mm/year in males) and mandible head widths (right: 0.42 mm/year in females, 0.49 mm/year in males; left: 0.52 mm/year in females, 0.68 mm/year in males). Additionally, in the orbital region, the orbital width underwent two periods of rapid growth i.e., 0–5 and 10–18 years of age, whilst the anterior interorbital distance noted no significant increase after 7.5 years of age. xiv b) Sexual dimorphism: Males displayed overall larger measurements than females in all the parameters, except for the anterior interorbital distance and the zygomatic arch lengths (ZAL) on the right and left, as females displayed larger measurements. Although these differences were not statistically significant (p>0.05). The only measurements which displayed statistically significant differences between males and females were the left orbital height (p = 0.048), nasal aperture height (p = 0.048) and the mandible width (p = 0.05), in which males displayed larger measurements than females. c) Age estimation: The measurements which displayed the strongest correlation to age were the ZAD (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 which could be used to estimate age. Discussion and conclusion: The findings from this study have outlined the development of the viscerocranium in subadult individuals with African ancestry. This study discussed the correlation between the development patterns of each viscerocranial region with age. The data from this study can be a useful addition to the existing data on the skeletal developments of subadult South African individuals. Forensically the development of formulas for subadult individuals could be utilised in the age estimation of skeletal remains.