Three-dimensional mixed longitudinal study of facial growth changes and variability of facial form in preschool children using stereophotogrammetry

Three-Dimensional Geometric Morphometric Characterization of Facial Sexual Dimorphism in Juveniles

Background: The characterization of facial sexual dimorphic patterns in healthy populations serves as valuable normative data to tailor functionally effective surgical treatments and predict their aesthetic outcomes and to identify dysmorphic facial traits related to hormonal disorders and genetic syndromes. Although the analysis of facial sexual differences in juveniles of different ages has already been investigated, few studies have approached this topic with three-dimensional (3D) geometric morphometric (GMM) analysis, whose interpretation may add important clinical insight to the current understanding. This study aims to investigate the location and extent of facial sexual variations in juveniles through a spatially dense GMM analysis. Methods: We investigated 3D stereophotogrammetric facial scans of 304 healthy Italians aged 3 to 18 years old (149 males, 155 females) and categorized into four different age groups: early childhood (3-6 years), late childhood (7-12 years), puberty (13-15 years), and adolescence (16-18 years). Geometric morphometric analyses of facial shape (allometry, general Procrustes analysis, Principal Component Analysis, Procrustes distance, and Partial Least Square Regression) were conducted to detail sexually dimorphic traits in each age group. Results: The findings confirmed that males have larger faces than females of the same age, and significant differences in facial shape between the two sexes exist in all age groups. Juveniles start to express sexual dimorphism from 3 years, even though biological sex becomes a predictor of facial soft tissue morphology from the 7th year of life, with males displaying more protrusive medial facial features and females showing more outwardly placed cheeks and eyes. Conclusions: We provided a detailed characterization of facial change trajectories in the two sexes along four age classes, and the provided data can be valuable for several clinical disciplines dealing with the craniofacial region. Our results may serve as comparative data in the early diagnosis of craniofacial abnormalities and alterations, as a reference in the planning of personalized surgical and orthodontic treatments and their outcomes evaluation, as well as in several forensic applications such as the prediction of the face of missing juveniles.

The relationship between facial directional asymmetry, handedness, chewing side preference, and eyedness

We aimed to describe facial directional asymmetry (DA) in individuals with different manifestations of laterality. Due to the overlap between brain and face development, a relationship between the manifestation of brain laterality and DA is hypothesised. These findings could clarify the relationship between the brain and facial phenotype and help to plan facial or oral motor rehabilitation. The DA of 163 healthy individuals was assessed by two complementary 3D methods: landmark and polygonal surface analysis using colour-coded maps. Handedness was assessed using the Edinburgh Handedness Inventory, while chewing side and eye preferences were self-reported. The results showed a similar DA pattern regardless of sex and laterality (the right-sided protrusion of the forehead, nose, lips, and chin) and a slightly curved C-shape of the midline in landmark analysis. A relationship between lateralized behaviours and DA was found only in males, in females the DA pattern was more homogenous. Right-handed individuals and right-side chewers showed a protrusion of the right hemiface. Males, left-handed and left-side chewers, manifested a protrusion of the left lateral hemiface. We suggest that these specific differences in males may be due to their typically higher level of brain asymmetry. No apparent relationship was found between eyedness and DA.

A cross-sectional study: correlation of forehead morphology and dentoskeletal malocclusion in Chinese people

BACKGROUND

The lateral profile is an important indicator of facial attractiveness. This study explored the general characteristics of the forehead profile and protrusion, and their relationship with related factors in structure and development.

METHODS

Four hundred fourteen Chinese participants in the Yangtze River Delta region were involved. Including 206 males (17.15 ± 7.68 years old) and 208 females (18.35 ± 8.06 years old); 94 children (8.54 ± 2.21 years old, ranging from 4 to 12 years old), 166 adolescents (14.83 ± 1.50 years old, ranging from 13 to 17 years old), and 154 adults (25.52 ± 4.89, 18 years or older). The frontal section of the forehead was used to explore its shape. The straight distance between the vertical line of the FH plane through the nasal root point and its parallel line, which is tangential to the forehead, indicates the forehead prominence. Frontal sinus width was measured using the method described by Mahmood.

RESULTS

The general shape of the forehead was straight and slightly bulged near the eyebrow arch in males but rounder in females. The average forehead protrusion in males was higher than that in females in adults. Significant differences in forehead protrusion between the dentoskeletal classifications and growth phases were notable. Frontal protrusion significantly correlated with frontal sinus depth, especially in males, adults, Class I, and those whose convex points were located in the lower section of the forehead.

CONCLUSIONS

Age, race, and sex affect the forehead protrusion and frontal sinus width. Forehead protrusion may be an indicator of dentoskeletal deformities in the early stage. And dentoskeletal deformities may impair the correlation between the frontal sinuses and forehead protrusion during development.

TRIAL REGISTRATION

This retrospective, cross-sectional study was reviewed and approved by the Research Ethical Committee (T2020008), and registered at ClinicalTrial.gov with an identified number (ChiCTR2100041913).

A semi-automatic three-dimensional technique using a regionalized facial template enables facial growth assessment in healthy children from 1.5 to 5.0 years of age

Objectives

To develop a semi-automatic technique to evaluate normative facial growth in healthy children between the age of 1.5 and 5.0 years using three-dimensional stereophotogrammetric images.

Materials and Methods

Three-dimensional facial images of healthy children at 1.5, 2.0, 2.5, 3.0, 4.0 and 5.0 years of age were collected and positioned based on a reference frame. A general face template was used to extract the face and its separate regions from the full stereophotogrammetric image. Furthermore, this template was used to create a uniform distributed mesh, which could be directly compared to other meshes. Average faces were created for each age group and mean growth was determined between consecutive groups for the full face and its separate regions. Finally, the results were tested for intra- and inter-operator performance.

Results

The highest growth velocity was present in the first period between 1.5 and 2.0 years of age with an average of 1.50 mm (±0.54 mm) per six months. After 2.0 years, facial growth velocity declined to only a third at the age of 5.0 years. Intra- and inter-operator variability was small and not significant.

Conclusions

The results show that this technique can be used for objective clinical evaluation of facial growth. Example normative facial averages and the corresponding facial growth between the age 1.5 and 5.0 years are shown.

Clinical Relevance

This technique can be used to collect and process facial data for objective clinical evaluation of facial growth in the individual patient. Furthermore, these data can be used as normative data in future comparative studies.

Age- and Sex-Related Changes in Labial Dimensions of Sudanese Youngs of Arab Descent: A Three-Dimensional Cross-Sectional Study

Proper evaluation of facial features during growth and development requires the knowledge of anthropometric reference values validated for ethnicity, sex and age. In order to provide information concerning the normal sex-related size of the lips during childhood and young adulthood in Sudanese people of Arab descent, the three-dimensional coordinates of nine labial soft tissue landmarks were obtained by a laser scanner in 332 male and 386 female healthy Northern Sudanese subjects aged 3-30 years. Six labial linear distances, the vermilion height to mouth width ratio, vermilion areas and lip volumes were calculated and averaged for age and sex. Comparisons were performed by factorial analysis of variance (p < 0.01). All labial dimensions significantly increased with age. Significant effects of sex were found for four measurements only, with very small effect size; nonetheless, lips and their parts grew faster in females than in males at almost all ages. Philtrum width was the first linear distance that attained adult values. The vermilion height to mouth width ratio was nearly constant across the age groups. Data collected in this study contribute to information about ethnic-specific lip morphology during growth and development. As orolabial features change over time with their own pattern, the relevant age-related trends should be properly considered for clinical treatment planning.