De Novo Dissecting the Three-Dimensional Facial Morphology of 2379 Han Chinese Individuals

Phenotypic diversity, especially that of facial morphology, has not been fully investigated in the Han Chinese, which is the largest ethnic group in the world. In this study, we systematically analyzed a total of 14,838 facial traits representing 15 categories with both a large-scale three-dimensional (3D) manual landmarking database and computer-aided facial segmented phenotyping in 2379 Han Chinese individuals. Our results illustrate that homogeneous and heterogeneous facial morphological traits exist among Han Chinese populations across the three geographical regions: Zhengzhou, Taizhou, and Nanning. We identified 1560 shared features from extracted phenotypes, which characterized well the basic facial morphology of the Han Chinese. In particular, heterogeneous phenotypes showing population structures corresponded to geographical subpopulations. The greatest facial variation among these geographical populations was the angle of glabella, left subalare, and right cheilion (p = 3.4 × 10-161). Interestingly, we found that Han Chinese populations could be classified into northern Han, central Han, and southern Han at the phenotypic level, and the facial morphological variation pattern of central Han Chinese was between the typical differentiation of northern and southern Han Chinese. This result was highly consistent with the results revealed by the genetic data. These findings provide new insights into the analysis of multidimensional phenotypes as well as a valuable resource for further facial phenotype-genotype association studies in Han Chinese and East Asian populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00109-x.

A retrospective cephalometric study on the craniofacial morphology of adult patients with unoperated submucous cleft palate

This retrospective cross-sectional study reviewed adult patients with unrepaired SMCP, OCP and normal control and performed comprehensive skeletal and soft tissue morphological analyses basing on lateral cephalometric radiographs. One way-ANOVA and rank-sum tests detected potential intergroup differences. 32 subjects with unrepaired SMCP, 42 with unrepaired OCP and 28 noncleft normal controls were enrolled. Both the SMCP and OCP groups were significantly different from the normal controls in sagittal maxillary length, jaw relationship, facial profile angle, nasal base and nasal tip prominence, upper lip position, and lower lip protrusion. S-N-A angle in the control group (82.25 ± 2.74°) was significantly greater than in the SMCP (77.96 ± 4.05°, p<0.001) and OCP (78.55 ± 2.93°, p<0.001) groups. Nasolabial angle in the control group (99.18 ± 8.76°) was significantly greater than in the SMCP (91.75 ± 8.93°, p = 0.002) and OCP (93.69 ± 7.24°, p = 0.020) groups. No significant difference was detected between the SMCP and the OCP group in other measurements except upper facial height. Within the limitations of the study it seems that craniofacial growth is impaired in patients with submucous clefts to the same extent as in patients with a conventional cleft palate.

Development and accuracy of artificial intelligence-generated prediction of facial changes in orthodontic treatment: a scoping review

Artificial intelligence (AI) has been utilized in soft-tissue analysis and prediction in orthodontic treatment planning, although its reliability has not been systematically assessed. This scoping review was conducted to outline the development of AI in terms of predicting soft-tissue changes after orthodontic treatment, as well as to comprehensively evaluate its prediction accuracy. Six electronic databases (PubMed, EBSCOhost, Web of Science, Embase, Cochrane Library, and Scopus) were searched up to March 14, 2023. Clinical studies investigating the performance of AI-based systems in predicting post-orthodontic soft-tissue alterations were included. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and Joanna Briggs Institute (JBI) appraisal checklist for diagnostic test accuracy studies were applied to assess risk of bias, while the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) assessment was conducted to evaluate the certainty of outcomes. After screening 2500 studies, four non-randomized clinical trials were finally included for full-text evaluation. We found a low level of evidence indicating an estimated high overall accuracy of AI-generated prediction, whereas the lower lip and chin seemed to be the least predictable regions. Furthermore, the facial morphology simulated by AI via the fusion of multimodality images was considered to be reasonably true. Since all of the included studies that were not randomized clinical trials (non-RCTs) showed a moderate to high risk of bias, more well-designed clinical trials with sufficient sample size are needed in future work.

Prediction of condylar movement envelope surface based on facial morphology

The present study aimed to predict the envelope surfaces from facial morphology. Condylar envelope surfaces for 34 healthy adults were formed and simplified as sagittal section curves. Cephalometric and maximum mandibular moving distances measurement were performed on the participants. There was no statistically significant difference (p = 0.763) between the left and right maximum lateral movements. There was a statistically significant difference in the mandibular body length between the sexes. The envelope surfaces were divided into type 1 with H_p2 ≥ 1/3 H_p1 and type 2 with H_p2 < 1/3 × H_p1. SNA and SNB for type 2 were significantly greater than those for type 1 (p < 0.001). Therefore, the participants were divided into four groups based on gender and envelope surface morphology. The curves could be fitted using the second-order Fourier function (R-square ≥0.95). Six facial parameters were selected and a matrix was used to map facial morphology to the envelope surface. Individual sagittal curves were predicted using the matrix and facial parameters, and the envelope surface was predicted using the curve and the condyle model. Deviation analysis for the predicted envelope surface using the actual envelope as a reference was carried out (root mean square = 0.9970 mm ± 0.2918 mm). This method may lay a foundation for the geometric design of artificial fossa components of temporomandibular joint replacement systems. It may improve prosthesis design without flexible tissue repair and guide the movement of the artificial joint head.

Rediscovering the value of images in supporting personal identification of missing migrants

The crisis concerning the identification of dead migrants is forcing forensic scientists to deal with the unavailability of classical antemortem (AM) data such as radiological information and DNA. However many times there is abundant AM photographic data of which the availability and quality is underestimated. Independently of when facial image comparison can be used as a valid identification method, description of the unexpected quality and quantity of images in the scenario of unidentified migrant decedents is given in this observational study. It focuses on the overall characteristics of the AM images available for a group of 74 missing migrants related to the disaster of October 3rd, 2013. 394 images were collected: an average of 6 for each missing person. 18% are original pictures, 47.5% scans of original images, 9.9% scans of printed images while 9.4% downloaded from social networks such as Facebook. 42.7% of images resulted in focus. Among all the images, about the 10% has been used in the personal identification process to ascertain the identity of 22 persons, because of the visibility of identifying details (facial, dental and body features). The importance of such a finding should not be diminished by its simplicity. Today, those involved in collecting AM information from relatives of dead migrants are underestimating the possible presence of images, even in sub-Saharan populations, where, contrary to belief and data, technology, though simple, is available and images may turn out to be abundant and useful (and at times the only resort) for identification.

Morphological description and evolutionary significance of 300 ka hominin facial bones from Hualongdong, China

Late Middle Pleistocene hominins in Africa displaying key modern morphologies by 315 ka are claimed as the earliest Homo sapiens. Evolutionary relationships among East Asian hominins appear complex due to a growing fossil record of late Middle Pleistocene hominins from the region, reflecting mosaic morphologies that contribute to a lack of consensus on when and how the transition to modern humans transpired. Newly discovered 300 ka hominin fossils from Hualongdong, China, provide further evidence to clarify these relationships in the region. In this study, facial morphology of the juvenile partial cranium (HLD 6) is described and qualitatively and quantitatively compared with that of other key Early, Middle, and Late Pleistocene hominins from East Asia, Africa, West Asia, and Europe and with a sample of modern humans. Qualitatively, facial morphology of HLD 6 resembles that of Early and Middle Pleistocene hominins from Zhoukoudian, Nanjing, Dali, and Jinniushan in China, as well as others from Java, Africa, and Europe in some of these features (e.g., supraorbital and malar regions), and Late Pleistocene hominins and modern humans from East Asia, Africa, and Europe in other features (e.g., weak prognathism, flat face and features in nasal and hard plate regions). Comparisons of HLD 6 measurements to group means and multivariate analyses support close affinities of HLD 6 to Late Pleistocene hominins and modern humans. Expression of a mosaic morphological pattern in the HLD 6 facial skeleton further complicates evolutionary interpretations of regional morphological diversity in East Asia. The prevalence of modern features in HLD 6 suggests that the hominin population to which HLD 6 belonged may represent the earliest pre-modern humans in East Asia. Thus, the transition from archaic to modern morphology in East Asian hominins may have occurred at least by 300 ka, which is 80,000 to 100,000 years earlier than previously recognized.

A genome-wide association study of facial morphology identifies novel genetic loci in Han Chinese

The human face is a heritable surface with many complex sensory organs. In recent years, many genetic loci associated with facial features have been reported in different populations, yet there is a lack of studies on the Han Chinese population. Here, we report a genome-wide association study of 3D normal human faces of 2,659 Han Chinese with autosegment phenotypes of facial morphology. We identify single-nucleotide polymorphisms (SNPs) encompassing four genomic regions showing significant associations with different facial regions, including SNPs in DENND1B associated with the chin, SNPs among PISRT1 associated with eyes, SNPs between DCHS2 and SFRP2 associated with the nose, and SNPs in VPS13B associated with the nose. We replicate 24 SNPs from previously reported genetic loci in different populations, whose candidate genes are DCHS2, SUPT3H, HOXD1, SOX9, PAX3, and EDAR. These results provide a more comprehensive understanding of the genetic basis of variation in human facial morphology.

Esthetic outcome after nasal reconstruction with paramedian forehead flap and bilobed flap

The incidence of skin cancer, which often affects the facial skin, has risen worldwide. After resecting such facial lesions, plastic reconstruction is necessary in most cases. The paramedian forehead flap (PFF) and the bilobed flap (BF) are commonly used for nasal reconstruction, but whether patients and physicians are satisfied with the esthetics is undetermined? In this study, scar questionnaires (Manchester Scar Scale, Vancouver Scar Scale, and Patient and Observer Scar Assessment Scale) and optical three-dimensional (3D) imaging were used for subjective and objective evaluation of esthetical outcomes after plastic reconstruction of the nose in 30 patients. The distances between landmarks and changes in volume between the treated and both the mirrored, healthy side of the face as well as an untreated, matched control group were measured using the optical (3D) scans. The questionnaires ascertained whether the patient was content with the esthetical outcome of both flaps. In the opinion of the observer, the esthetical outcome of both flaps was sufficient; only a few of the measured distances differed significantly between the patients and the control group. However, the measured volume differences of the donor site of the flap differed significantly between the PFF group and the control group (p = 0.0078). The BF was used for smaller defects, while the PFF was used for major defects. Besides a greater donor-side morbidity for the PFF, both flaps led to esthetically sufficient results and could be used for the reconstruction of the nose depending on the defect size and localization.

A preliminary investigation of the effects of prenatal alcohol exposure on facial morphology in children with Autism Spectrum Disorder

Alcohol exposure during pregnancy has been associated with altered brain development and facial dysmorphology. While Autism Spectrum Disorder (ASD) is not specifically related to distinct facial phenotypes, recent studies have suggested certain facial characteristics such as increased facial masculinity and asymmetry may be associated with ASD and its clinical presentations. In the present study, we conducted a preliminary investigation to examine facial morphology in autistic children with (n = 37; mean age = 8.21 years, SD = 2.72) and without (n = 100; mean age = 8.37 years, SD = 2.47) prenatal alcohol exposure. Using three-dimensional facial scans and principal component analysis, we identified a facial shape associated with prenatal alcohol exposure in autistic children. However, variations in the alcohol-related facial shape were generally not associated with behavioral and cognitive outcomes. These findings suggest that while early exposure to alcohol may influence the development of facial structures, it does not appear to be associated with ASD phenotypic variability. Importantly, although these findings do not implicate a role for prenatal alcohol exposure in the etiology of ASD, further research is warranted to investigate the link between prenatal alcohol exposure and facial morphology differences among neurodevelopmental conditions.

Morphological changes of the human face after massive weight-loss due to bariatric surgery

The aim of this study was to evaluate the morphological changes in the face of obese patients during massive weight loss using a more reliable method than two dimensional photographs or tape measures. The faces of 23 patients were recorded prior to and six months after bariatric surgery. Distances between important anatomical landmarks of the face were calculated and the volume of the neck was compared. The distance between the Tragion and Subnasale (132.7 ± 6.804 mm to 131.5 ± 6.866 mm; p = 0.0003), and the distance between Tragion and Stomion became significantly longer 136.0 ± 8.016 mm to 134.3 ± 7.698 mm; p = 0.0031), while distances between the Tragion and Pogonion (150.2 ± 8.216 mm to 148.3 ± 8.383 mm; p < 0.0001), Tragion and Menton (152.3 ± 9.037 mm to 148.9 ± 9.623 mm; p < 0.0001), and Tragion and tip of the nose (144.9 ± 7.273 mm to 144.0 ± 7.416 mm; p = 0.0023) were significantly reduced. The mean volume loss of the neck was 75.218 ± 40.197 ml. No significant correlation was found between total weight loss and cervical volume loss (r = 0.3447; p = 0.1072). The morphological changes of the face after massive weight loss vary in different areas of the face. Patients and their attending physicians must be aware of the face's morphology change after massive weight loss in an extent that does not correlate with the total weight loss of the patient.

An Exploration of the Relationships Among Facial Dimensions, Age, Sex, Dominance Status, and Personality in Rhesus Macaques (Macaca mulatta)

Aspects of personality in nonhuman primates have been linked to health, social relationships, and life history outcomes. In humans as well as nonhuman primates, facial morphology is associated with assertiveness, aggression, and measures of dominance status. In this study we aimed to examine the relationship among facial morphology, age, sex, dominance status, and ratings on the personality dimensions Confidence, Openness, Assertiveness, Friendliness, Activity, and Anxiety in rhesus macaques (Macaca mulatta). We measured facial width-to-height ratio (fWHR) and lower-height/full-height ratio (fLHFH) using photographs from 109 captive rhesus macaques, which observers also assessed for dominance status and personality, and explored the associations among facial morphology, age, sex, dominance status, and personality. fWHR and fLHFH personality associations depended on age category: Assertiveness was associated with higher fWHR and fLHFH, and Confidence was associated with lower fWHR and fLHFH, but all these associations were consistent only in individuals <8 yr. of age. We found fWHR and fLHFH to not be consistently associated with sex or dominance status; compared to younger individuals, we found few associations with fWHR and fLHFH for individuals older than 8 yr., which may be due to limited sample size. Our results indicate that in macaques <8 yr. old, facial morphology is associated with the Assertiveness and Confidence personality dimensions, which is consistent with results suggesting a relationship between fWHR and trait aggression in humans and assertiveness in brown capuchins, all of which implies that fWHR might be a cue to assertive and aggressive traits.

A comparison between 2D and 3D methods of quantifying facial morphology

Objectives

Currently, two & three-dimensional (2D & 3D) imaging techniques have largely replaced the direct anthropometric method in the assessment of facial morphology, but the difference between the two techniques was not quantified. Therefore, the aim of this study was to compare and quantify (the difference between) the two techniques.

Materials and methods

The faces of 150 subjects (75 males, 75 females) of northern Nigeria, predominantly Hausa ethnic group, were photographed (using digital camera) and scanned (using a 3D surface laser scanner). Facial dimensions were generated from the resulting virtual 2D and 3D models. Data were analyzed using R-statistic software & Paired sample t-test/Pearson correlation were conducted to compare the two methods and to quantify the level of closeness between the two measurements.

Results

Intraclass correlation coefficient (ICC) was very low (0.26) for the 3D and 2D measurements indicating the level of differences between the methods. Measurements taken with laser scanner were higher relative to the one taken by camera. The mean differences between the 3D and the 2D methods of quantifying facial morphology indicated a statistically significant positive difference. CONCLUSION: 2D and 3D anthropometry cannot be used interchangeably since there exists statistically significant variation between the two methods.

Cone beam computed tomography evaluation of the relationship between atlantodental interval and skeletal facial morphology in adolescents

Introduction

In the pediatric population, computed tomography examination of the upper cervical spine plays an important role in the diagnosis of neurological injuries involving that region. Due to the interconnected nature of the craniofacial structures, a structural change in one is expected to also cause changes in the other structures.

Objective

The aim of this study was to evaluate relationships between atlantodental interval, cervical vertebral morphology, and facial structure in healthy adolescents using cone beam computed tomography.

Methods

Thirty subjects aged 14–20 years (10 males, mean age: 17.2 years; 20 females, mean age: 17.9 years) were included in the study. The anterior, lateral and posterior atlantodental intervals, and vertical and anteroposterior dimensions of the first and second cervical vertebrae were evaluated from cone beam computed tomography images. Facial morphology was evaluated using 7 parameters on lateral cephalometric cone beam computed tomography images and 6 parameters on posteroanterior images. The Mann–Whitney U test and Wilcoxon test were used for statistical analyses.

Results

Comparisons between males and females showed that most parameters were larger in males, with significant differences in vertical facial dimensions (anterior lower face height: p = 0.05; anterior upper face height: p = 0.001), (distance between the most internal point of the frontozygomatic suture and midsagittal reference plane; p = 0.01), (the distance between the deepest point of the right alveolar maxillar process and midsagittal reference plane; p = 0.001), and C2 vertebral dimensions. The anterior and lateral atlantodental interval values correlated with maxilla position relative to the mandible angle, and the anterior atlantodental interval correlated with lower anterior facial height (p = 0.05). Dimensional measurements of the C1 and C2 vertebrae were correlated with both anterior facial heights and some posteroanterior parameters.

Conclusion

Sagittal, vertical, and transverse facial dimensions and positions were strongly associated with C1 and C2 vertebral dimensions, and the maxillomandibular relationship may affect atlantodental interval. Therefore, including craniofacial features in assessment of the atlantodental area and vertebral distances in adolescents may be beneficial.

Prenatal alcohol exposure and facial morphology in a UK cohort

BACKGROUND

High levels of prenatal alcohol exposure are known to cause an array of adverse outcomes including fetal alcohol syndrome (FAS); however, the effects of low to moderate exposure are less-well characterized. Previous findings suggest that differences in normal-range facial morphology may be a marker for alcohol exposure and related adverse effects.

METHODS

In the Avon Longitudinal Study of Parents and Children, we tested for an association between maternal alcohol consumption and six FAS-related facial phenotypes in their offspring, using both self-report questionnaires and the maternal genotype at rs1229984 in ADH1B as measures of maternal alcohol consumption.

RESULTS

In both self-reported alcohol consumption (N = 4233) and rs1229984 genotype (N = 3139) analyses, we found no strong statistical evidence for an association between maternal alcohol consumption and facial phenotypes tested. The directions of effect estimates were compatible with the known effects of heavy alcohol exposure, but confidence intervals were largely centered around zero.

CONCLUSIONS

There is no strong evidence, in a sample representative of the general population, for an effect of prenatal alcohol exposure on normal-range variation in facial morphology.

The Facial Width-to-Height Ratio Predicts Sex Drive, Sociosexuality, and Intended Infidelity

Previous research has linked the facial width-to-height ratio (FWHR) to a host of psychological and behavioral characteristics, primarily in men. In two studies, we examined novel links between FWHR and sex drive. In Study 1, a sample of 145 undergraduate students revealed that FWHR positively predicted sex drive. There were no significant FWHR × sex interactions, suggesting that FWHR is linked to sexuality among both men and women. Study 2 replicated and extended these findings in a sample of 314 students collected from a different Canadian city, which again demonstrated links between the FWHR and sex drive (also in both men and women), as well as sociosexuality and intended infidelity (men only). Internal meta-analytic results confirm the link between FWHR and sex drive among both men and women. These results suggest that FWHR may be an important morphological index of human sexuality.

Analysis of facial morphology of UK and US general election candidates: Does the 'power face' exist?

AIMS

To determine the frequency of recognised morphologic facial phenotypes among the UK and US election candidates and to assess whether there is a relationship between facial morphology and success in general elections.

METHODS

Facial morphology analysis of prime ministerial and presidential candidates in the UK and US elections was performed. Direct facial measurements were made from frontal images and facial morphological indices calculated for all candidates. Anthropometric facial phenotype was determined and comparisons made between the elected leaders and unelected runner-up candidates. Paired candidates who had different facial types were analysed as a subgroup, with the probabilities of electoral success calculated.

RESULTS

Data were available for 45 subjects: 22 election winners and 23 unelected runner-ups. Our data showed some variation in facial morphology between the groups. The predominant facial phenotype in both groups was leptoprosopic (long and/or narrow face), accounting for 40% (n = 18). Mesoprosopic (average dimension) and euryprosopic (short and/or broad) facial type represented 31% (n = 14) and 18% (n = 8), respectively. A majority of the sample (n = 36) demonstrated a malar width to mandibular angle width ratio consistent with the modern 'power face' proportion. Subgroup analysis showed a significant association with success in an election when leptoprosopic candidates were paired against candidates of another facial phenotype (p < 0.05).

CONCLUSION

Leptoprosopic (long and/or narrow) facial phenotype with a wide mandibular angle width is predominant in the UK and US election candidates. Moreover, this facial phenotype appears to be associated with greater electoral success, supporting the concept of a modern political 'power face'.

Morphological impact on patients of maxillomandibular advancement surgery for the treatment of obstructive sleep apnea-hypopnea syndrome

INTRODUCTION

The aim of this study is to evaluate the experience of patients who have benefited from maxillomandibular advancement surgery for the treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS), and also the morphological modifications measured on pre- and postoperative lateral headfilms.

PATIENTS AND METHODS

Twenty-three patients aged 24 to 64 (M=46.8) who had undergone bimaxillary advancement osteotomy for the treatment of OSAHS filled in a questionnaire concerning their overall satisfaction following surgery, the modification of their facial appearance as perceived by themselves and their family and friends, the change in their smile, and the slimmer and more youthful appearance of their face. Measurements of bone and skin points were also performed on lateral cephalograms before and after surgery so as to assess the advancement of the bony bases (maxillary, mandibular and chin advancement) and the impact on soft tissue by analysis of the skin profile.

RESULTS

A total of 91.3% of the patients were satisfied overall following the surgical procedure; 78.3% considered that their faces were improved or unchanged; 39.1% found their faces slimmer and 34.8% thought they looked more youthful. Average maxillary, mandibular and chin advancements with respect to the base of the skull were, respectively, 7.4mm, 11.1mm and 14.1mm. Advancement of the stomion point with respect to the Frankfurt plane was 8.3mm on average, reflecting a significant forward movement of the upper and lower lips.

CONCLUSION

Despite greater maxillary and mandibular advancements than in traditional orthognathic surgery, patients reacted positively to these morphological changes, considering in more than a third of cases that their faces looked slimmer or more youthful. It can thus be concluded that overall satisfaction is high, with a morphological impact that is satisfactory and well-accepted by patients postoperatively.

The effect of adenoid hypertrophy on maxillofacial development: an objective photographic analysis

Background

Deformity in the dental arc and facial skeleton by adenoid hypertrophy due to chronic mouth breathing is a well-known process. Most of the related studies have been based on cephalometric analyses. The aim of this study is to detect the presence of skeletal deformities on the soft tissue by analyzing distances and angles on photographs.

Methods

Ninety-seven children having between 25 and 100 % of adenoids, ages 4–12 years (48 boys, 49 girls), and 90 cases having 0–25 % adenoid tissue, ages 4–12 years (54 boys, 36 girls), were studied by clinical history, physical examination (including endoscopy), and standardized clinical photographs. The children and parents were asked if any of the following were present in the children: snoring, sleep apnea, daytime sleepiness, poor school performance, mouth breathing during sleep, smoking parents, and restlessness during sleep.

Results

The assessment of linear and angular measurements on the clinical photographs showed, in the group having thicker adenoids compared with controls, a statistically significant increase in the distance between nasion and tip and nasion and subnasale and in the angle between Frankfort horizontal plane-gnathion-angulus mandible; there was also a statistically significant decrease in the distance between endocanthion and exocanthion and the angles between tragion-angulus mandible and gnathion and between nasion-angulus mandible and gnathion.

Conclusions

The analyses showed a significant increase in the anterior face height and increase in the angle between Frankfort horizontal plane-gnathion-angulus mandible and a retropositioned and posterior-rotated mandible due to thicker adenoids.

Trial registration

2010/140 Date: 04 January 2010.

Face morphology: Can it tell us something about body weight and fat?

This paper proposes a method for an automatic extraction of geometric features, related to weight parameters, from 3D facial data acquired with low-cost depth scanners. The novelty of the method relies both on the processing of the 3D facial data and on the definition of the geometric features which are conceptually simple, robust against noise and pose estimation errors, computationally efficient, invariant with respect to rotation, translation, and scale changes. Experimental results show that these measurements are highly correlated with weight, BMI, and neck circumference, and well correlated with waist and hip circumference, which are markers of central obesity. Therefore the proposed method strongly supports the development of interactive, non obtrusive systems able to provide a support for the detection of weight-related problems.

Association between facial growth pattern and facial muscle activity: A prospective cross-sectional study

OBJECTIVE

To evaluate the relationship between facial growth pattern and electromyography (EMG) of facial muscles: anterior temporalis, masseter, buccinators, orbicularis oris, mentalis and anterior digastric.

PATIENTS AND METHODS

The sample consisted of 77 subjects aged between 18-28 years (mean age 21.10±2.03), with dental Class I relationship, normal overjet and overbite, balanced facial profile, no signs of temporomandibular disorders, and no previous orthodontic treatment. Facial growth pattern was determined on the lateral cephalograms according to the Björk sum (sum of the N-S-Ar, S-Ar-Go, and Ar-Go-Me angles) dividing the sample into three groups: horizontal facial pattern group (24 subjects), normal facial pattern group (41 subjects), and vertical facial pattern group (12 subjects). The EMG of anterior temporalis, masseter, buccinator, orbicularis oris, mentalis and anterior digastric muscles were examined for each patient in the rest position and in functional positions (central maximum intercuspation, chewing on right side, chewing on left side and swallowing). Mean values and standard deviation of EMG were obtained and compared between the three groups.

RESULTS

At rest, the EMG of the masseter, orbicularis oris and anterior digastric were higher in the vertical facial pattern group compared with the other two groups, with a moderate positive correlation between the EMG of these muscles and the Björk sum (P<.01). In contrast, during central maximum intercuspation, the activity of the anterior temporalis, masseter and buccinator was significantly lower in the vertical facial pattern group compared with the two other groups, with a moderate negative correlation between the Björk sum and EMG in the maximum central intercuspation position of these muscles (P<.01).

CONCLUSIONS

A significant relationship was found between facial muscle activity and facial growth pattern. The findings suggest that the activity of masticatory and perioral muscles could play a role in the direction of the facial growth.

A 3D analysis of Caucasian and African American facial morphologies in a US population

INTRODUCTION

This study aimed to compare facial morphologies of an adult African-American population to an adult Caucasian-American population using three-dimensional (3D) surface imaging.

MATERIALS AND METHODS

The images were captured using a stereophotogrammetric system (3dMDface(TM) system). Subjects were aged 19-30 years, with normal body mass index and no gross craniofacial anomalies. Images were aligned and combined using RF6 Plus Pack 2 software to produce a male and female facial average for each population. The averages were superimposed and the differences were assessed.

RESULTS

The most distinct differences were in the forehead, alar base and perioricular regions. The average difference between African-American and Caucasian-American females was 1·18±0·98 mm. The African-American females had a broader face, wider alar base and more protrusive lips. The Caucasian-American females had a more prominent chin, malar region and lower forehead. The average difference between African-American and Caucasian-American males was 1·11±1·04 mm. The African-American males had a more prominent upper forehead and periocular region, wider alar base and more protrusive lips. No notable difference occurred between chin points of the two male populations.

CONCLUSIONS

Average faces were created from 3D photographs, and the facial morphological differences between populations and genders were compared. African-American males had a more prominent upper forehead and periocular region, wider alar base and more protrusive lips. Caucasian-American males showed a more prominent nasal tip and malar area. African-American females had broader face, wider alar base and more protrusive lips. Caucasian-American females showed a more prominent chin point, malar region and lower forehead.

Toward DNA-based facial composites: preliminary results and validation

The potential of constructing useful DNA-based facial composites is forensically of great interest. Given the significant identity information coded in the human face these predictions could help investigations out of an impasse. Although, there is substantial evidence that much of the total variation in facial features is genetically mediated, the discovery of which genes and gene variants underlie normal facial variation has been hampered primarily by the multipartite nature of facial variation. Traditionally, such physical complexity is simplified by simple scalar measurements defined a priori, such as nose or mouth width or alternatively using dimensionality reduction techniques such as principal component analysis where each principal coordinate is then treated as a scalar trait. However, as shown in previous and related work, a more impartial and systematic approach to modeling facial morphology is available and can facilitate both the gene discovery steps, as we recently showed, and DNA-based facial composite construction, as we show here. We first use genomic ancestry and sex to create a base-face, which is simply an average sex and ancestry matched face. Subsequently, the effects of 24 individual SNPs that have been shown to have significant effects on facial variation are overlaid on the base-face forming the predicted-face in a process akin to a photomontage or image blending. We next evaluate the accuracy of predicted faces using cross-validation. Physical accuracy of the facial predictions either locally in particular parts of the face or in terms of overall similarity is mainly determined by sex and genomic ancestry. The SNP-effects maintain the physical accuracy while significantly increasing the distinctiveness of the facial predictions, which would be expected to reduce false positives in perceptual identification tasks. To the best of our knowledge this is the first effort at generating facial composites from DNA and the results are preliminary but certainly promising, especially considering the limited amount of genetic information about the face contained in these 24 SNPs. This approach can incorporate additional SNPs as these are discovered and their effects documented. In this context we discuss three main avenues of research: expanding our knowledge of the genetic architecture of facial morphology, improving the predictive modeling of facial morphology by exploring and incorporating alternative prediction models, and increasing the value of the results through the weighted encoding of physical measurements in terms of human perception of faces.

Three-dimensional quantitative evaluation of facial morphology in adults with unilateral cleft lip and palate, and patients without clefts

The aims of this study were to assess the quantitative values of measurements using proportion indices in the craniofacial region in patients with repaired, non-syndromic, complete unilateral cleft lip and palate (UCLP), and compare them with a control group who did not have clefts using the non-invasive systems of 3-dimensional technology. Three-dimensional measurements of the facial surfaces of 15 Malay patients who had UCLP repaired and 100 Malay control patients aged 18-25 years were analysed. The 3-dimensional images of the respondents' faces were captured using the VECTRA-3D Stereophotogrammetry System. Eleven craniofacial proportions were assessed using a combination of 18 linear measurements obtained from 21 anthropometric soft tissue landmarks. These measurements were used to produce proportion indices to find the differences in the morphological features between the groups, and assessed using the independent sample t test and z scores. There were significant differences between the groups in 7 out of 11 craniofacial proportion indices (p=0.001-0.044). Z scores of 2 indices were disproportionate. They were nasal index (which was severely supernormal) and upper lip index (which was moderately supernormal). Patients with UCLP had higher mean z scores, indicating that patients with UCLP tended to have larger faces than the control group. There were clinically important differences mainly in the nasolabial area, where the nose and the upper lip were wider, larger, or flatter in patients with UCLP.