Sources of variation in the 3dMDface and Vectra H1 3D facial imaging systems

Morphometric Assessment of Facial Morphology in Infants with Orofacial Clefts up to two Years of Age: A Three-Dimensional Cross-Sectional Study

OBJECTIVE

To assess modelled facial development of infants with unilateral cleft lip (CL) and cleft lip and palate (UCLP) compared to controls up to two years of age.

DESIGN AND PARTICIPANTS

A total of 209 facial images of children (CL: n = 37; UCLP: n = 39; controls: n = 137) were obtained in four age categories (T0 = 0.2-0.5; T1 = 0.6-1.0; T2 = 1.1-1.5; T3 = 1.6-2.0 years) and were evaluated using stereophotogrammetry and geometric morphometry. All patients underwent lip surgery before T0, patients with UCLP underwent palatoplasty (T0, T1 before palatoplasty; T2, T3 after palatoplasty).

RESULTS

In patients with CL, the forehead was significantly retracted (p ≤ 0.001), while the supraorbital and ocular regions were prominent (p ≤ 0.001). The oronasal region appeared convex (p ≤ 0.001). The lower lip and chin were non-significantly protruded. In patients with UCLP, a significantly retracted forehead and prominent supraorbital region were apparent (p ≤ 0.001). A retrusive oronasal region (p ≤ 0.001) was observed in the middle face. The chin was anteriorly protruded (p ≤ 0.01). No progression of deviations was found with increasing age. After the first year, a slight improvement in the morphological features became apparent. The shape variability of the clefts and controls overlapped, suggesting a comparable modelled facial development.

CONCLUSIONS

The facial morphology of individuals with cleft was comparable to the norm. Shape deviation was apparent in the oronasal region, forehead, and chin, which minimised with increasing age even in complete clefts.

Frontiers in Three-Dimensional Surface Imaging Systems for 3D Face Acquisition in Craniofacial Research and Practice: An Updated Literature Review

Digitalizing all aspects of dental care is a contemporary approach to ensuring the best possible clinical outcomes. Ongoing advancements in 3D face acquisition have been driven by continuous research on craniofacial structures and treatment effects. An array of 3D surface-imaging systems are currently available for generating photorealistic 3D facial images. However, choosing a purpose-specific system is challenging for clinicians due to variations in accuracy, reliability, resolution, and portability. Therefore, this review aims to provide clinicians and researchers with an overview of currently used or potential 3D surface imaging technologies and systems for 3D face acquisition in craniofacial research and daily practice. Through a comprehensive literature search, 71 articles meeting the inclusion criteria were included in the qualitative analysis, investigating the hardware, software, and operational aspects of these systems. The review offers updated information on 3D surface imaging technologies and systems to guide clinicians in selecting an optimal 3D face acquisition system. While some of these systems have already been implemented in clinical settings, others hold promise. Furthermore, driven by technological advances, novel devices will become cost-effective and portable, and will also enable accurate quantitative assessments, rapid treatment simulations, and improved outcomes.

Can smartphones be used for routine dental clinical application? A validation study for using smartphone-generated 3D facial images

OBJECTIVES

To compare the accuracy of smartphone-generated three-dimensional (3D) facial images to that of direct anthropometry (DA) and 3dMD with the aim of assessing the validity and reliability of smartphone-generated 3D facial images for routine clinical applications.

MATERIALS AND METHODS

Twenty-five anthropometric soft-tissue facial landmarks were labelled manually on 22 orthognathic surgery patients (11 males and 11 females; mean age 26.2 ± 5.3 years). For each labelled face, two imaging operations were performed using two different surface imaging systems: 3dMDface and Bellus3D FaceApp. Next, 42 inter-landmark facial measurements amongst the identified facial landmarks were measured directly on each labelled face and also digitally on 3D facial images. The measurements obtained from smartphone-generated 3D facial images (SGI) were statistically compared with those from DA and 3dMD.

RESULTS

SGI had slightly higher measurement values than DA and 3dMD, but there was no statistically significant difference between the mean values of inter-landmark measures across the three methods. Clinically acceptable differences (≤3 mm or ≤5°) were observed for 67 % and 74 % of measurements with good agreement between DA and SGI, and 3dMD and SGI, respectively. An overall small systematic bias of ± 0.2 mm was observed between the three methods. Furthermore, the mean absolute difference between DA and SGI methods was highest for linear (1.41 ± 0.33 mm) as well as angular measurements (3.07 ± 0.73°).

CONCLUSIONS

SGI demonstrated fair trueness compared to DA and 3dMD. The central region and flat areas of the face in SGI are more accurate. Despite this, SGI have limited clinical application, and the panfacial accuracy of the SGI would be more desirable from a clinical application standpoint.

CLINICAL SIGNIFICANCE

The usage of SGI in clinical practice for region-specific macro-proportional facial assessment involving central and flat regions of the face or for patient education purposes, which does not require accuracy within 3 mm and 5° can be considered.

Geometric learning and statistical modeling for surgical outcomes evaluation in craniosynostosis using 3D photogrammetry

BACKGROUND AND OBJECTIVE

Accurate and repeatable detection of craniofacial landmarks is crucial for automated quantitative evaluation of head development anomalies. Since traditional imaging modalities are discouraged in pediatric patients, 3D photogrammetry has emerged as a popular and safe imaging alternative to evaluate craniofacial anomalies. However, traditional image analysis methods are not designed to operate on unstructured image data representations such as 3D photogrammetry.

METHODS

We present a fully automated pipeline to identify craniofacial landmarks in real time, and we use it to assess the head shape of patients with craniosynostosis using 3D photogrammetry. To detect craniofacial landmarks, we propose a novel geometric convolutional neural network based on Chebyshev polynomials to exploit the point connectivity information in 3D photogrammetry and quantify multi-resolution spatial features. We propose a landmark-specific trainable scheme that aggregates the multi-resolution geometric and texture features quantified at every vertex of a 3D photogram. Then, we embed a new probabilistic distance regressor module that leverages the integrated features at every point to predict landmark locations without assuming correspondences with specific vertices in the original 3D photogram. Finally, we use the detected landmarks to segment the calvaria from the 3D photograms of children with craniosynostosis, and we derive a new statistical index of head shape anomaly to quantify head shape improvements after surgical treatment.

RESULTS

We achieved an average error of 2.74 ± 2.70 mm identifying Bookstein Type I craniofacial landmarks, which is a significant improvement compared to other state-of-the-art methods. Our experiments also demonstrated a high robustness to spatial resolution variability in the 3D photograms. Finally, our head shape anomaly index quantified a significant reduction of head shape anomalies as a consequence of surgical treatment.

CONCLUSION

Our fully automated framework provides real-time craniofacial landmark detection from 3D photogrammetry with state-of-the-art accuracy. In addition, our new head shape anomaly index can quantify significant head phenotype changes and can be used to quantitatively evaluate surgical treatment in patients with craniosynostosis.

Validation of low-cost mobile phone applications and comparison with professional imaging systems for three-dimensional facial imaging: A pilot study

PURPOSE

The objective of this study was to investigate the accuracies of three-dimensional (3D) facial scanning mobile phone applications as compared to professional 3D facial imaging systems.

MATERIALS AND METHODS

A manikin head model was used as the subject for comparing six 3D facial imaging systems which comprised three professional 3D scanners (3dMDface, Artec Eva and Vectra H2) and three mobile phone applications (Bellus3D, ScandyPro and Hedges). For each system, five scans were taken to analyse (1) linear accuracy using 9 measurements (2) global and (3) regional 3D accuracy of the scanned surface by root mean square (RMS) and colour map analysis. Another set of five scans was repeated by a second operator to evaluate the inter-operator reproducibility for each system.

RESULTS

All the facial imaging systems had absolute errors lesser than 1.0 mm for the linear measurements. The technical error of measurement (TEM) for inter-examiner and intra-examiner linear measurements were within acceptable limits. Artec Eva, Vectra H2 and Scandy Pro had poor global 3D trueness (RMS > 1.0 mm) but good 3D regional trueness (RMS < 1.0 mm). 3dMDface, Bellus3D Face App and Heges had good global and regional 3D trueness. All the facial imaging systems had good global and regional 3D precision and reproducibility (RMS < 1.0 mm).

CONCLUSION

This study demonstrated that mobile phone 3D scanning applications had comparable trueness, precision and reproducibility to professional systems. Colour map analysis supplemented the use of the RMS value to demonstrate facial regions of significant deviation. Clinicians should also consider the specific area or region of inaccuracies for each system to determine whether the chosen system is appropriate for the clinical condition or procedure.

CLINICAL SIGNIFICANCE

Mobile phone 3D facial imaging applications may be as accurate as 3D professional facial scanning systems for craniomaxillofacial purposes. However, the choice of the system may vary depending on the specific area of interest.

Applications of three-dimensional imaging techniques in craniomaxillofacial surgery: A literature review

Three-dimensional (3D) imaging technologies are increasingly used in craniomaxillofacial (CMF) surgery, especially to enable clinicians to get an effective approach and obtain better treatment results during different preoperative and postoperative phases, namely during image acquisition and diagnosis, virtual surgical planning (VSP), actual surgery, and treatment outcome assessment. The article presents an overview of 3D imaging technologies used in the aforementioned phases of the most common CMF surgery. We searched for relevant studies on 3D imaging applications in CMF surgery published over the past 10 years in the PubMed, ProQuest (Medline), Web of Science, Science Direct, Clinical Key, and Embase databases. A total of 2094 articles were found, of which 712 were relevant. An additional 26 manually searched articles were included in the analysis. The findings of the review demonstrated that 3D imaging technology is becoming increasingly popular in clinical practice and an essential tool for plastic surgeons. This review provides information that will help researchers and clinicians consider the use of 3D imaging techniques in CMF surgery to improve the quality of surgical procedures and achieve satisfactory treatment outcomes.

Age- and sex-related differences in 3D facial shape and muscle pressure in subjects with normal occlusion

BACKGROUND AND OBJECTIVE(S): (1) To derive descriptive statistics of three-dimensional (3D) facial shape, lip and cheek muscle pressure in subjects of European descent with normal dental occlusion. (2) To analyse the effect of age and sex on 3D-facial soft tissue morphology and muscle pressure in the same sample. (3) To assess the independent effect of muscle pressure on face shape.

METHOD

129 subjects with normal occlusion were cross-sectionally recruited and divided into: children (mixed dentition), adolescents and adults (permanent dentition, < and ≥18 years respectively). Muscle pressure was recorded using the Iowa Oral Performance Instrument. MeshLab, MeVisLab and Meshmonk tool box were used to clean, annotate landmarks and generate the 3D images. Two-way analysis of variance and post-hoc tests were used to analyse age and sex differences in face shape and muscle pressure. The effect of muscle pressure on face shape was analysed by Pearson correlation and Partial Least Square regression.

RESULTS

Significant facial differences were observed between adults and adolescents and adults and children in both sexes, showing flattening of cheeks and lips and protrusion of nose and chin. Significant cheek protrusion and retrusion of the vertical midface were found in adult women compared to men. Lip and cheek pressure increased with age, but their effect on face shape was not significant.

CONCLUSIONS

This study provides 3D age- and sex-specific facial models and muscle pressure of subjects without malocclusion. These can be used as a reference for clinicians focused on facial assessment in treatment planning and follow-up.

Facial scanning technologies in the era of digital workflow: A systematic review and network meta-analysis

PURPOSE

The aim of this network meta-analysis is to evaluate the accuracy of various face-scanning technologies in the market, with respect to the different dimensions of space (x, y, and z axes). Furthermore, attention will be paid to the type of technologies currently used and to the best practices for high-quality scan acquisition.

MATERIAL AND METHODS

The review was conducted following the PRISMA guidelines and its updates. A thorough search was performed using the digital databases MEDLINE, PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials by entering research lines or various combinations of free words. The main keywords used during the search process were "photogrammetry", "laser scanner", "optical scanner", "3D, and "face".

RESULTS

None of the included technologies significantly deviated from direct anthropometry. The obtained mean differences in the distances between the considered landmarks range from 1.10 to -1.74 mm.

CONCLUSION

Limiting the movements of the patient and scanner allows for more accurate facial scans with all the technologies involved. Active technologies such as laser scanners (LS), structured light (SL), and infrared structured light (ISL) have accuracy comparable to that of static stereophotogrammetry while being more cost-effective and less time-consuming.

Quantification of Facial Allograft Edema During Acute Rejection: A Software-Based 3-Dimensional Analysis

BACKGROUND

Acute rejection (AR) is a common complication in facial transplant (FT) patients associated with allograft edema and erythema. Our study aims to demonstrate the feasibility of using software-based 3-dimensional (3D) facial analysis to quantify edema as it resolves during/after AR treatment in an FT patient.

METHODS

Our patient is a 23-year-old man who underwent a face and bilateral hand allotransplant in August 2020. The Vectra H1 (Canfield, Fairfield, NJ) portable scanner was used to capture 3D facial images at 8 time points between postoperative day (POD) 392 and 539. The images were analyzed with the Vectra Software using a rejection-free image (POD 539) as a control.

RESULTS

Edema increased in the periorbital, lower third, and submandibular regions before AR treatment (POD 392-415). At POD 448, total facial edema was reduced to near baseline values in response to plasmapheresis and thymoglobulin (+156.94 to +28.2 mL). The fastest and most notable response to treatment was seen in the periorbital region, while some edema remained in the submandibular (+19.79 mL) and right lower third (+8.65 mL) regions. On POD 465, after the initial improvement, the edema increased but was resolved with steroid use. Facial edema did not correlate with the histopathological evaluation in our patient.

CONCLUSIONS

We demonstrated the feasibility of analyzing 3D facial images to quantify edema during/after AR treatment in an FT patient. Our analysis detected edema changes consistent with AR followed by an improvement after treatment. This technology shows promise for noninvasive monitoring of FT patients.

Validation of Vectra 3D Imaging Systems: A Review

Aim: Three-dimensional facial imaging systems are a useful tool that is gradually replacing two-dimensional imaging and traditional anthropometry with calipers. In this varied and growing landscape of new devices, Canfield (Canfield Scientific, Parsippany, NJ, USA) has proposed a series of static and portable 3D imaging systems. The aim of this systematic review was to evaluate the current literature regarding the validation of Canfield’s Vectra imaging systems. Materials and Methods: A search strategy was developed on electronic databases including PubMed, Web of Science and Scopus by using specific keywords. After the study selection phase, a total of 10 articles were included in the present review. Results: A total of 10 articles were finally included in the present review. For six articles, we conducted a validation of the Vectra static devices, focusing especially on the Vectra M5, Vectra M3 and Vectra XT. For four articles, we validated the Vectra H1 portable system. Conclusions: All of the reviewed articles concluded that Canfield’s Vectra 3D imaging systems are capable of capturing accurate and reproducible stereophotogrammetric images. Minor errors were reported, particularly in the acquisition of the perioral region, but all the evaluated devices are considered to be valid and accurate tools for clinicians.

Decoding the Human Face: Challenges and Progress in Understanding the Genetics of Craniofacial Morphology

Variations in the form of the human face, which plays a role in our individual identities and societal interactions, have fascinated scientists and artists alike. Here, we review our current understanding of the genetics underlying variation in craniofacial morphology and disease-associated dysmorphology, synthesizing decades of progress on Mendelian syndromes in addition to more recent results from genome-wide association studies of human facial shape and disease risk. We also discuss the various approaches used to phenotype and quantify facial shape, which are of particular importance due to the complex, multipartite nature of the craniofacial form. We close by discussing how experimental studies have contributed and will further contribute to our understanding of human genetic variation and then proposing future directions and applications for the field.

Static and Motion Facial Analysis for Craniofacial Assessment and Diagnosing Diseases

Deviation from a normal facial shape and symmetry can arise from numerous sources, including physical injury and congenital birth defects. Such abnormalities can have important aesthetic and functional consequences. Furthermore, in clinical genetics distinctive facial appearances are often associated with clinical or genetic diagnoses; the recognition of a characteristic facial appearance can substantially narrow the search space of potential diagnoses for the clinician. Unusual patterns of facial movement and expression can indicate disturbances to normal mechanical functioning or emotional affect. Computational analyses of static and moving 2D and 3D images can serve clinicians and researchers by detecting and describing facial structural, mechanical, and affective abnormalities objectively. In this review we survey traditional and emerging methods of facial analysis, including statistical shape modeling, syndrome classification, modeling clinical face phenotype spaces, and analysis of facial motion and affect. Expected final online publication date for the Annual Review of Biomedical Data Science, Volume 5 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Reproducibility of Novel Soft-Tissue Landmarks on Three-Dimensional Human Facial Scan Images in Caucasian and Asian

Background

Three-dimensional surface imaging is established in many disciplines for objective facial acquisition regarding anthropometry. Former studies addressed the validation of landmark-based measurements for single race. In order to distinguish racial difference, the reproducibility of the landmark measurements must first be validated.

Objectives

Our purpose is to validate the reproducibility of 46 facial soft-tissue landmarks on x, y, z axes to prove their reliability as 3D reference points.

Methods

The study included 80 European Caucasian and 80 Chinese volunteers. Standardized 3D surface imaging was performed using Vectra 3D system. Two raters identified and defined 46 landmarks (138 coordinates), then repeatedly 3D-imaged volunteers' facial region in separate sessions. Coordinates' reproducibility of landmarks is divided into three categories (< 0.5 mm, < 1 mm, and >1 mm) for intra- and inter-rater reproducibility assessments.

Results

Coordinates' reproducibility of 160 samples was distributed as follows: Intra-rater: < 0.5 mm (45%), < 1 mm (42%), >1 mm (13%); inter-rater: < 0.5 mm (31.2%), < 1 mm (42%), > 1 mm (26.8%). The reproducibility of landmarks in nasal tip region differs slightly between Caucasians and Asians. Compared to females, males typically have higher landmark reproducibility in lip and chin region. However, there were no differences in the reproducibility ranking of landmarks by gender.

Conclusion

The majority of the 46 landmarks in the 3D plane are reproducible to 1 mm, which is clinically acceptable. All selected landmarks showed strong consistency across race and gender, suggesting their potential use as reference points in prospective clinical practice.

Level of Evidence IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00266-021-02642-4.

Accuracy of 3-dimensional stereophotogrammetry: Comparison of the 3dMD and Bellus3D facial scanning systems with one another and with direct anthropometry

INTRODUCTION

The objective of this study was to compare the accuracy of 3-dimensional (3D) digital facial photographs taken by the Bellus3D Face Camera Pro (Bellus3D) (Bellus3D Inc, Los Gatos, Calif) and the 3dMDface system (3dMD) (3dMD Inc, Atlanta, Ga) with one another and with direct anthropometry (DA).

METHODS

A mannequin head was selected as the research object. Twenty facial landmarks were labeled on the basis of the 8 interlandmark distances and 5 angles that were defined. A 150-mm digital Vernier caliper (Mitutoyo Inc, Tokyo, Japan) with an accuracy of 0.02 mm was applied to directly measure the interlandmark distances, and the angles were calculated according to the law of cosines. All the measurements were conducted 3 times by each operator under identical conditions. Then, each scanner was used to acquire 3D photographs 5 times, generating 10 digital stereophotographs. Linear distances and angles were measured on the 3D facial photographs reconstructed with open-source MeshLab software (ISTI [Italian National Research Council], Rome, Italy). Each linear distance and angle were measured 3 times by 1 operator, and 3 examiners conducted the measurements independently. To obtain the trueness, equivalence tests were applied to compare the measurements of the 2 scanners and DA. In addition, the average absolute deviations were calculated to directly compare the trueness of 3 methods (Bellus3D vs 3dMD vs DA). Finally, the intraclass correlation coefficient was used to assess the interobserver agreement and the precision of 2 scanners.

RESULTS

As for the trueness, 7 out of 8 of the linear distance measurements (N-Pn, Sn-Pog, ORE-IRE, OLE-ILE, RLC-RMC, LLC-LMC, and CR-CL) and 3 out of 5 of the angular measurements (MLA, NFA, and INI) obtained by 3dMD were equivalent to those obtained by DA. Five out of 8 measurements (N-Pn, Sn-Pog, RLC-RMC, LLC-LMC, and CR-CL) and 1 out of 5 of the angular measurements (MLA) obtained by Bellus3D were equivalent to the measurements obtained with DA. All but 3 of the measurements (ORE-IRE, NFA, and INI) obtained with Bellus3D were equivalent to 3dMD. The mean absolute difference between 3dMD and DA was 0.36 ± 0.20 mm and 0.45° ± 0.56°; the deviation between Bellus3D and DA was 0.61 ± 0.47 mm and 0.99° ± 0.61°; and the deviation between Bellus3D and 3dMD was 0.38 ± 0.37 mm and 0.62° ± 0.39°. Regarding the precision of the 2 scanners, the intraclass correlation coefficient value of 3dMD was approximately 1.00, and that of Bellus3D was 0.99. The interobserver agreement for each linear and angular measurement was 0.99.

CONCLUSIONS

The trueness of each scanner was clinically acceptable for diagnosis and treatment planning. The precision of 3D photographs obtained by 3dMD and Bellus3D showed good scanning repeatability. The interobserver agreement between the 3 operators was rated as excellent (0.99).

Vectra 3D Simulation in Lower Eyelid Blepharoplasty: How Accurate is it?

BACKGROUND

Estimating the volume of fat to be resected during lower lid blepharoplasty can be challenging. While the excess fat is clearly visible in the upright position, it retracts into the orbital cavity when the patient is in decubitus. Several tools have been developed to predict the volume required for adequate outcomes and to reduce the risk of complications. Among these, 3D photography, in addition to being noninvasive, radiation-free, portable and relatively inexpensive, can be used to make simulations.

OBJECTIVE

To assess the level of agreement between Vectra H1 camera simulations and the outcome of lower eyelid blepharoplasties with volume removal based on these simulations.

METHODS

Preoperatively, a 3D camera and simulation software (Vectra H1, Canfield Imaging Systems) was used to estimate the fat pad volume to be resected from the lower eyelids in a sample of 35 patients (female n = 34) aged 55 years on average. Following the procedure, the patients were photographed at 1, 3 and 6 months and the outcome was compared to the simulation.

RESULTS

The agreement between the simulated volume and the intraoperative volume was high. While the difference between the postoperative volume and the simulated volume decreased over time, at 6 months the actual volume was still 0.30 mL (right eye) and 0.24 mL (left eye) larger than the simulated volume.

CONCLUSIONS

A systematic and significant difference was found between the simulation volume and the postoperative volume. The low level of agreement observed suggests that the accuracy of the tested software is insufficient for reliable simulations.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Large-scale open-source three-dimensional growth curves for clinical facial assessment and objective description of facial dysmorphism

Craniofacial dysmorphism is associated with thousands of genetic and environmental disorders. Delineation of salient facial characteristics can guide clinicians towards a correct clinical diagnosis and understanding the pathogenesis of the disorder. Abnormal facial shape might require craniofacial surgical intervention, with the restoration of normal shape an important surgical outcome. Facial anthropometric growth curves or standards of single inter-landmark measurements have traditionally supported assessments of normal and abnormal facial shape, for both clinical and research applications. However, these fail to capture the full complexity of facial shape. With the increasing availability of 3D photographs, methods of assessment that take advantage of the rich information contained in such images are needed. In this article we derive and present open-source three-dimensional (3D) growth curves of the human face. These are sequences of age and sex-specific expected 3D facial shapes and statistical models of the variation around the expected shape, derived from 5443 3D images. We demonstrate the use of these growth curves for assessing patients and show that they identify normal and abnormal facial morphology independent from age-specific facial features. 3D growth curves can facilitate use of state-of-the-art 3D facial shape assessment by the broader clinical and biomedical research community. This advance in phenotype description will support clinical diagnosis and the understanding of disease pathogenesis including genotype–phenotype relations.

3D facial phenotyping by biometric sibling matching used in contemporary genomic methodologies

The analysis of contemporary genomic data typically operates on one-dimensional phenotypic measurements (e.g. standing height). Here we report on a data-driven, family-informed strategy to facial phenotyping that searches for biologically relevant traits and reduces multivariate 3D facial shape variability into amendable univariate measurements, while preserving its structurally complex nature. We performed a biometric identification of siblings in a sample of 424 children, defining 1,048 sib-shared facial traits. Subsequent quantification and analyses in an independent European cohort (n = 8,246) demonstrated significant heritability for a subset of traits (0.17-0.53) and highlighted 218 genome-wide significant loci (38 also study-wide) associated with facial variation shared by siblings. These loci showed preferential enrichment for active chromatin marks in cranial neural crest cells and embryonic craniofacial tissues and several regions harbor putative craniofacial genes, thereby enhancing our knowledge on the genetic architecture of normal-range facial variation.

The Intersection of the Genetic Architectures of Orofacial Clefts and Normal Facial Variation

Unaffected relatives of individuals with non-syndromic cleft lip with or without cleft palate (NSCL/P) show distinctive facial features. The presence of this facial endophenotype is potentially an expression of underlying genetic susceptibility to NSCL/P in the larger unselected population. To explore this hypothesis, we first partitioned the face into 63 partially overlapping regions representing global-to-local facial morphology and then defined endophenotypic traits by contrasting the 3D facial images from 264 unaffected parents of individuals with NSCL/P versus 3,171 controls. We observed distinct facial features between parents and controls across 59 global-to-local facial segments at nominal significance (p ≤ 0.05) and 52 segments at Bonferroni corrected significance (p < 1.2 × 10-3), respectively. Next, we quantified these distinct facial features as univariate traits in another dataset of 8,246 unaffected European individuals and performed a genome-wide association study. We identified 29 independent genetic loci that were associated (p < 5 × 10-8) with at least one of the tested endophenotypic traits, and nine genetic loci also passed the study-wide threshold (p < 8.47 × 10-10). Of the 29 loci, 22 were in proximity of loci previously associated with normal facial variation, 18 were near genes that show strong evidence in orofacial clefting (OFC), and another 10 showed some evidence in OFC. Additionally, polygenic risk scores for NSCL/P showed associations with the endophenotypic traits. This study thus supports the hypothesis of a shared genetic architecture of normal facial development and OFC.

Accuracy of Portable Face-Scanning Devices for Obtaining Three-Dimensional Face Models: A Systematic Review and Meta-Analysis

The use of three-dimensional face-scanning systems to obtain facial models is of increasing interest, however, systematic assessments of the reliability of portable face-scan devices have not been widely conducted. Therefore, a systematic review and meta-analysis were performed considering the accuracy of facial models obtained by portable face-scanners in comparison with that of those obtained by stationary face-scanning systems. A systematic literature search was conducted in electronic databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for articles published from 1 January 2009 to 18 March 2020. A total of 2806 articles were identified, with 21 articles available for the narrative review and nine studies available for meta-analysis. The meta-analysis revealed that the accuracy of the digital face models generated by the portable scanners was not significantly different from that of the stationary face-scanning systems (standard mean difference (95% confidence interval) = -0.325 mm (-1.186 to 0.536); z = -0.74; p = 0.459). Within the comparison of the portable systems, no statistically significant difference was found concerning the accuracy of the facial models among scanning methods (p = 0.063). Overall, portable face-scan devices can be considered reliable for obtaining facial models. However, caution is needed when applying face-scanners with respect to scanning device settings, control of involuntary facial movements, landmark and facial region identifications, and scanning protocols.