SN Facial linear distances Landmarks 1 Special head height v-en 2 Special face height en-gn 3 Forehead height II tr-n 4 Nose length n-sn 5 Lower face height sn-gn 6 Height of calva v-tr 7 Forehead height I tr-g 8 Special upper face height
I g-sn 9 Interocular distance en-en 10 Nasal width al-al 11 Upper facial width zy-zy 12 Mouth width ch-ch 13 Orbital length ex-en TABLE 3: Nine neoclassical canon facial proportions and their variations.
Facial width, total face height, short forehead height, long forehead height, upper face height, nasal bridge length, nose height, morphological face height, and lower face height computed from readings of the Akinlolu-Raji image-processing algorithm were analyzed using z-test (P ≤ 0.05) of 2010 Microsoft Excel statistical software.
Pairwise comparative statistical analyses of computed mean values of facial parameters (mean [+ or -] standard deviation [SD]) in millimeters between Vernier caliper (1D anthropometry) and Akinlolu-Raji image-processing algorithm (3D anthropometry) measurements in male and female control subjects showed lower or higher, but no significant differences ( P [sub][B] > 0.05) in 100% of measured parameters: Total face height, long forehead height, upper face height, morphological face height, nose height, and lower face height [Figure 1].
Distances of the facial width (zygion to zygion), total face height (trichion to gnathion), short forehead height (trichion to glabella), long forehead height (trichion to nasion), upper face height (trichion to subnasale), morphological face height (nasion to gnathion), nasal bridge length (nasion to pronasale), nose height (nasion to subnasale), and lower face height (subnasale to gnathion) were computed in this study [Figure 1].
Statistical analyses of measurements of anteromedian aspects of the face (mean [+ or -] SD in millimeters) showed nonsignificant higher mean values ( P > 0.05) in 87.5% of parameters: Total face height, short forehead height, long forehead height, upper face height, morphological face height, nasal bridge length, and nose height in Yoruba males compared to females [Table 1].
Upper face height
-Mouth width Index (Figure 11, colour plate II) (Sn-St/ChR-ChL, males= 0.42 [+ or -] 0.04, females = 0.39 [+ or -] 0.05, P=0.00) and Lower face height- Mouth width index (Figure 12, colour plate II) (Sn-Me/ChR-ChL, males = 1.34 [+ or -] 0.10, females = 1.23 [+ or -] 0.13, P=0.00) showed significant sexual differences.
Morphologic trait N = 118[dagger] N = 118[double dagger] Thigh length -0.161 -0.106 Leg length -0.166 -0.142 Upper arm length -0.208(*) -0.062 Forearm length -0.207(*) -0.059 Biiliocristal diameter -0.156 -0.143 Bitrochanteric diameter -0.134 -0.086 Transverse chest diameter -0.222(*) -0.031 Chest depth -0.123 -0.157 Biacromial diameter -0.186(*) -0.106 Head length -0.135 -0.103 Head breadth -0.027 -0.007 Chest circumference -0.150 -0.107 Upper arm circumference -0.120 -0.091 Calf circumference -0.205(*) -0.114 Biocular breadth -0.212(*) -0.235(*) Bizygomatic breadth -0.142 -0.097 Bigonial breadth -0.140 -0.089 Upper face height
-0.157 -0.056 Trunk length -0.154 -0.101 Crown-rump length -0.156 -0.112 * Indicates significant at P [less than] 0.05 without sequential Bonferroni.
A variety of factors have been theorized and reported to be responsible for lower incisor segment such as inclination of mandibular incisors during mixed dentition,4 inclination and size of mandibular permanent 1st molars5, high mandibular plane angles, short mandibular body lengths, great upper face height, and small vertical dimensions in upper posterior segments6.
One of the earliest studies conducted on the relationship between lower arch crowding and vertical craniofacial dimensions was by Sakuda et al6 in 1976 and they found a positive relationship of lower arch crowding with high mandibular plane angles, short mandibular body lengths, great upper face height, and small vertical dimensions in the upper posterior segments.