Results

Thirty-five computed tomography scans were analysed. Three were discarded because one was distorted, another had a significant lesion (swelling) in the parotid region and another because of tribal marks (TM) as illustrated in Fig. 4.

Fig. 4: A subject with ethnic tribal marks (TM) on both cheeks, defined by the end of the green arrowhead

The 3-dimensional reformat scans of subjects showed a hair tie woven style, Figs. 5 A and 5B (defined by the end of the green arrowhead). When examined further on coronal views, the hair ties had a pulling effect on the scalp, with C-shaped shallow trenches (indicated by the end of the blue arrowhead) and crests of hair woven (end of green arrowhead), Fig. 5C.

Fig. 5: Hair tie woven style (a) in 3D reformat, (b) in bony window, and (c) pulling effect in coronal view. The end of the arrowhead defines the point of interest

In addition, the computed tomography bony windows of these subjects showed features of advanced periodontal disease, as illustrated in Figs. 6 A to 6 F and defined by the end of green arrowheads. Also, subjects showed missing teeth as defined by the end of the blue arrowhead. These pathology could affect the thickness of the mid-masseter and other muscles of mastication [43].

Fig. 6: a to 6f Evidence of advanced periodontal disease and missing teeth as demonstrated in scans. The end of the arrowhead describes points of interest

Statistical evaluations of these facial soft tissue thickness data were performed using SPSS (IBM Corporation, 1989, 2023) software. To lessen intra- and inter-observer errors, the measurements of the first ten subjects were completed thrice by the same researcher. The p-values of less than 0.05 showed reproducibility of good accuracy in measurements. All subjects were classified based on ethnicity and age brackets, Table 4, and by age, Appendix Table (Appendix 1). The Hausas are the majority subgroup.

Age | Hausa | Fulani | Yoruba | Dakarkari | Total
18–32 | 10 | 1 | - | - | 11
33–47 | 4 | - | 1 | - | 5
48–62 | 7 | 2 | - | - | 9
63–77 | 2 | 1 | - | 1 | 4
78–92 | - | 2 | - | - | 2
93–100 | 1 | - | - | - | 1
Total | 24 | 6 | 1 | 1 | 32

The younger age brackets were the most populated. After 63 years, there is a reduction in the number of subjects; presumably a reflection of the reduced life span of 54.95 years for this population [49].

The descriptive statistics for mean, minimum (min), maximum (max), range, standard deviation (STD), and counts of all measured midline facial soft tissue thickness points were calculated for the combined Nigerian female ethnicities (CNFE); see Table 5 below.

These values will be relevant in forensic facial reconstruction of deceased Nigerian female adults aged 18 years and above, especially if the age, ethnicity and body mass index are not known. This type of average values with no age sub-classification [24, 28, 39, 41] nor BMI [32, 37, 39] or weight classification has been published in various works. This dataset is similar to the data for the Nigerian adult male (Table 5).

FSTT point | Mean | Min | Max | Range | STD | Count | Mean midline values for Nigerian males
Vertex | 5.54 | 1.18 | 9.96 | 8.78 | 2.51 | 29 | 6.39
Supraglabella | 3.80 | 1.99 | 5.28 | 3.29 | 0.96 | 32 | 4.56
Glabella | 5.39 | 3.17 | 8.49 | 5.32 | 1.41 | 32 | 5.46
Nasion | 5.33 | 3.31 | 8.93 | 5.62 | 1.51 | 32 | 6.09
Mid-Nasal | 3.25 | 1.84 | 6.06 | 4.22 | 0.97 | 32 | 3.97
Rhinion | 2.59 | 1.71 | 4.24 | 2.53 | 0.59 | 32 | 3.35
Midphiltrum | 10.80 | 6.96 | 14.7 | 7.74 | 1.93 | 32 | 12.64
Upper lip border | 8.65 | 5.6 | 12 | 6.4 | 1.46 | 32 | 10.17
Lower lip border | 10.45 | 5.39 | 14.5 | 9.11 | 2.76 | 31 | 10.79
Labiomental | 11.79 | 6.42 | 17.2 | 10.78 | 3.66 | 30 | 12.4
Mental eminence | 10.81 | 6.36 | 16.0 | 9.64 | 3.08 | 31 | 10.36
Menton | 5.70 | 2.66 | 11.3 | 8.64 | 2.41 | 29 | 6.29

The descriptive statistics for both right and left sides of the face were also calculated (Table 6). The lowest facial soft tissue thickness is at the mlo point, a value of 3.25. The highest value for the Nigerian female is 22.20 at the lm point. The values for the right side of the face were compared with the left, Table 6 (comparison Table); there is marginally more tissue on the left side, which is consistent at all points. Bilateral differences (net differences between the right and left sides) for the Nigerian female were compared with the published data for the Nigerian male [43] (Table 6, comparison Table).

Descriptive statistics of facial soft tissue thickness for the Hausa female (HF) age range in years of 18 to 32 were estimated, Table 7.

The Nigerian adult male marginally displayed more soft tissue at some points (fe, lg, ln, sc, ic, mm) except at the lateral sides of the face (lm, sm2, lo, io, za, im2), where females show more soft tissue thickness, Table 8. These differences are also illustrated in (Appendix 2 and 3).

Right of CNFE | Left of CNFE |  | Comparison Table of CNFE CNME
FSTT points | Mean | Min | Max | Range | SD | Count | Mean | Min | Max | Range | SD | Count | D of CNFE lt - rt | *D of CNFE lt - rt | CNFElt > rt (%)RD | D ofCNMElt - rt | CNMElt > rt RD (%)
Frontal eminence | 4.36 | 1.6 | 7.69 | 6.09 | 1.40 | 32 | 4.47 | 2.27 | 7.8 | 5.53 | 1.34 | 32 | 0.11 | 0.08 | 2.43 | 0.39 | 8.18
Supraorbital | 5.43 | 2.26 | 8.08 | 5.82 | 1.48 | 32 | 5.58 | 2.38 | 8.73 | 6.35 | 1.52 | 32 | 0.15 | 0.10 | 2.73 | 0.32 | 5.58
Infraorbital | 10.41 | 5.77 | 15.4 | 9.63 | 2.88 | 32 | 10.50 | 6.53 | 15 | 8.47 | 2.71 | 32 | 0.09 | 0.03 | 0.85 | 0.15 | 1.59
Supraglenoid | 12.24 | 7.48 | 18.0 | 10.52 | 3.15 | 32 | 12.98 | 7.71 | 20 | 12.29 | 3.34 | 32 | 0.74 | 0.23 | 6.08 | 0.93 | 7.41
Zygomatic arch | 6.76 | 3.21 | 13.6 | 10.39 | 2.62 | 32 | 7.39 | 3.33 | 13.5 | 10.17 | 2.86 | 32 | 0.63 | 0.23 | 9.28 | 0.3 | 4.79
Lateral Orbit | 7.65 | 3.61 | 12.5 | 8.89 | 2.51 | 32 | 8.13 | 3.87 | 13.4 | 9.53 | 2.50 | 32 | 0.48 | 0.19 | 6.23 | 0.32 | 5.28
Lateral Glabella | 4.44 | 1.94 | 6.87 | 4.93 | 1.52 | 32 | 4.55 | 1.81 | 7.13 | 5.32 | 1.59 | 32 | 0.11 | 0.07 | 2.42 | 0.13 | 2.64
Lateral nasal | 6.95 | 3.93 | 11.8 | 7.87 | 1.90 | 32 | 7.40 | 4.32 | 14.8 | 10.48 | 2.19 | 32 | 0.45 | 0.22 | 6.43 | 0.32 | 4.31
lateral maxilla | 22.20 | 14.8 | 28.9 | 14.1 | 5.18 | 31 | 23.60 | 16.0 | 30.1 | 14.1 | 5.29 | 31 | 1.40 | 0.27 | 6.32 | 0.93 | 4.63
Lateral nostril | 9.11 | 6.81 | 12.0 | 5.19 | 2.26 | 31 | 9.39 | 7.01 | 12.2 | 5.19 | 2.31 | 31 | 0.28 | 0.12 | 3.05 | 0.5 | 5.36
Supracanine | 7.59 | 5.15 | 10.6 | 5.45 | 1.97 | 31 | 7.98 | 5.36 | 11.8 | 6.44 | 2.11 | 31 | 0.39 | 0.19 | 5.09 | 0.31 | 3.52
Infra-canine | 7.58 | 2.64 | 11.6 | 8.96 | 3.04 | 28 | 7.84 | 3.2 | 11.6 | 8.4 | 3.13 | 28 | 0.26 | 0.08 | 3.47 | 0.39 | 4.63
Mid-lateral orbit | 3.25 | 1.3 | 5.45 | 4.15 | 1.22 | 31 | 3.50 | 1.33 | 5.8 | 4.47 | 1.27 | 31 | 0.25 | 0.20 | 7.58 | 0.19 | 5.26
Supra-M2 | 21.64 | 11.8 | 34.9 | 23.1 | 6.05 | 31 | 23.05 | 14.7 | 36.4 | 21.7 | 7.25 | 31 | 1.41 | 0.21 | 6.64 | 0.81 | 4.06
Infra-M2 | 17.86 | 11.2 | 30.1 | 18.9 | 5.13 | 31 | 19.02 | 13.2 | 32,7 | 19.5 | 5.92 | 31 | 1.16 | 0.21 | 6.47 | 0.62 | 3.58
Mid-masseter | 20.22 | 11.7 | 32.0 | 20.3 | 5.63 | 31 | 20.98 | 14.5 | 28.1 | 13.6 | 5.28 | 31 | 0.76 | 0.14 | 3.75 | 0.33 | 1.53
Gonion | 16.75 | 5.73 | 26.2 | 20.47 | 7.00 | 29 | 17.53 | 6.6 | 28.3 | 21.7 | 7.55 | 29 | 0.78 | 0.11 | 4.64 | 1.04 | 6.28
Occlusal line | 19.61 | 9.17 | 29.0 | 19.83 | 7.57 | 29 | 20.62 | 10.6 | 29.3 | 18.7 | 8.07 | 29 | 1.10 | 0.13 | 5.15 | 1.09 | 5.59
Mid-mandible | 11.88 | 4.46 | 22.0 | 17.54 | 5.38 | 28 | 12.64 | 5.01 | 22.3 | 17.29 | 5.83 | 28 | 0.76 | 0.14 | 6.43 | 0.58 | 4.95

18–32 |  |  |  |  |  | 
FSTT point (midline) | Mean | Min | Max | Range | SD | Count
Vertex | 7.50 | 6.22 | 9.96 | 3.74 | 3.36 | 8
Supraglabella | 3.54 | 2.28 | 4.91 | 2.63 | 1.06 | 10
Glabella | 4.76 | 3.35 | 6.56 | 3.21 | 1.14 | 10
Nasion | 4.87 | 3.31 | 6.79 | 3.48 | 1.14 | 10
Mid-Nasal | 3.55 | 2.36 | 5.86 | 3.50 | 0.95 | 10
Rhinion | 2.56 | 2.09 | 3.53 | 1.44 | 0.44 | 10
Midphiltrum | 11.08 | 7.40 | 14.30 | 6.90 | 2.30 | 10
Upper lip border | 9.32 | 6.93 | 12.00 | 5.07 | 1.72 | 10
Lower lip border | 9.67 | 8.05 | 13.80 | 5.75 | 1.83 | 10
Labiomental point | 11.45 | 9.60 | 14.90 | 5.30 | 1.65 | 10
Mental eminence | 10.76 | 6.36 | 14.30 | 7.94 | 2.13 | 10
Menton | 4.97 | 2.66 | 6.85 | 4.19 | 2.45 | 8
18–32
FSTT point (right face) | Mean | Min | Max | Range | SD | Count
Frontal eminence | 4.53 | 3.51 | 6.16 | 2.65 | 1.00 | 10
Supraorbital | 5.80 | 4.06 | 8.08 | 4.02 | 1.22 | 10
Infraorbital | 8.86 | 5.77 | 13.80 | 8.03 | 2.50 | 10
Supraglenoid | 11.69 | 7.48 | 15.40 | 7.92 | 2.63 | 10
Zygomatic arch | 6.92 | 4.17 | 11.20 | 7.03 | 2.05 | 10
Lateral Orbit | 7.42 | 5.05 | 12.50 | 7.45 | 2.28 | 10
Lateral Glabella | 4.65 | 1.94 | 6.69 | 4.75 | 1.74 | 10
Lateral nasal | 6.10 | 3.93 | 11.80 | 7.87 | 2.41 | 10
lateral maxilla | 20.28 | 14.80 | 27.80 | 13.00 | 3.86 | 10
Lateral nostril | 9.46 | 7.05 | 12.00 | 4.95 | 1.63 | 10
supracanine | 8.34 | 5.92 | 10.60 | 4.68 | 1.77 | 10
Infra-canine | 7.86 | 4.92 | 11.60 | 6.68 | 2.11 | 10
Mid-lateral orbit | 3.48 | 2.24 | 5.26 | 3.02 | 0.99 | 10
Supra-M2 | 21.34 | 15.30 | 28.00 | 12.70 | 4.71 | 10
Infra-M2 | 18.40 | 11.20 | 26.40 | 15.20 | 4.85 | 10
Mid-masseter | 19.34 | 15.10 | 24.50 | 9.40 | 3.49 | 10
Gonion | 15.15 | 5.73 | 22.70 | 16.97 | 5.82 | 10
Occlusal line | 17.64 | 9.17 | 24.90 | 15.73 | 6.06 | 10
Mid-mandible | 10.58 | 4.46 | 18.30 | 13.84 | 5.30 | 9

FSTT | CNFE | CNME | CNME (18–32) | HF° (18–32) | Comparison Table
CNME – CNFE(Both these are the combined adult values) | CNME*(18–32) –HF° (18–32)
Vertex | 5.54 | 6.39 | 7.27 | 7.5 | 0.85 | −0.23
Supraglabella | 3.80 | 4.56 | 4.85 | 3.54 | 0.76 | 1.31
Glabella | 5.39 | 5.46 | 6.06 | 4.76 | 0.07 | 1.3
Nasion | 5.33 | 6.09 | 6.63 | 4.87 | 0.76 | 1.76*
Mid-nasal | 3.25 | 3.97 | 4.37 | 3.55 | 0.72 | 0.82
Rhinion | 2.59 | 3.35 | 3.31 | 2.56 | 0.76 | 0.75
Midphiltrum | 10.80 | 12.64 | 13.31 | 11.08 | 1.84* | 2.23*
Upper lip border | 8.65 | 10.17 | 10.92 | 9.32 | 1.52* | 1.6*
Lower lip border | 10.45 | 10.79 | 10.44 | 9.67 | 0.34 | 0.77
Labiomental point | 11.79 | 12.4 | 11.91 | 11.45 | 0.61 | 0.46
Mental eminence | 10.81 | 10.36 | 10.11 | 10.76 | −0.45 | −0.65
Menton | 5.70 | 6.29 | 6.33 | 4.97 | 0.59 | 1.36
Frontal eminence | 4.36 | 4.77 | 4.46 | 4.53 | 0.41 | −0.07
Supraorbital | 5.43 | 5.73 | 6.14 | 5.8 | 0.3 | 0.34
Infraorbital | 10.41 | 9.44 | 9.87 | 8.86 | −0.97 | 1.01
Supraglenoid | 12.24 | 12.55 | 12.58 | 11.69 | 0.31 | 0.89
Zygomatic arch | 6.76 | 6.26 | 6.27 | 6.92 | −0.5 | −0.65
Lateral Orbit | 7.65 | 6.06 | 6.01 | 7.42 | −1.59* | −1.41
Lateral Glabella | 4.44 | 4.92 | 5.50 | 4.65 | 0.48 | 0.85
Lateral nasal | 6.95 | 7.43 | 8.41 | 6.1 | 0.48 | 2.31*
lateral maxilla | 22.20 | 20.09 | 20.23 | 20.28 | −2.11* | −0.05
Lateral nostril | 9.11 | 9.33 | 9.77 | 9.46 | 0.22 | 0.31
supracanine | 7.59 | 8.80 | 9.54 | 8.34 | 1.21 | 1.2
Infra-canine | 7.58 | 8.42 | 8.91 | 7.86 | 0.84 | 1.05
Mid-lateral orbit | 3.25 | 3.61 | 3.94 | 3.48 | 0.36 | 0.46
Supra-M2 | 21.64 | 19.93 | 21.24 | 21.34 | −1.71* | −0.1
Infra-M2 | 17.86 | 17.34 | 18.50 | 18.4 | −0.52 | 0.1
Mid-masseter | 20.22 | 21.54 | 22.49 | 19.34 | 1.32 | 3.15*
Gonion | 16.75 | 16.57 | 16.45 | 15.15 | −0.18 | 1.3
Occlusal line | 19.61 | 19.51 | 20.63 | 17.64 | −0.1 | 2.99*
Mid-mandible | 11.88 | 11.71 | 11.27 | 10.58 | −0.17 | 0.69

This type of age sub-classification has been reported in other FSTT studies [2, 50]. The Hausa female (HF) (18 to 32) midline and right-side soft tissue thicknesses were compared with published data for the Nigerian male population of the same young adults (18 to 32 years) (Table 8). As with the older adult, the young adult male data show slight increases in values, but again not at the lateral side of the face, where there is a marginally more soft tissue at the za and lo in females (Table 8, comparative Table).