The effect of sex and age on facial shape directional asymmetry in adults: A 3D landmarks-based method study

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.

Applying 3D scanning to evaluate facial symmetry in Asian populations

BACKGROUND

Facial symmetry enhances attractiveness, with various therapies available to improve it. However, trends in facial asymmetry remain unclear. This study evaluates the differences between specific facial regions using 3D scanning to guide clinical treatment.

METHOD

The 3dMD face™ system (3dMD Ltd, USA) scanned the faces of 88 participants. Geomagic Wrap 2021 analyzed the left and right sides. Differences in the eyebrow peaks, eyebrow tails, eye ends, and mouth corners were evaluated.

RESULTS

Several participants showed a drooping right side of the face in the eyebrow peaks, eyebrow tails, eye ends, mouth corners, tubercula mentale, and mandibular margin positions. A higher proportion had deeper left nasolabial folds and marionette lines, whereas several others had deeper right tear ducts and lateral chin depressions. Several participants exhibited prominent right forehead and parotid masseter region, with prominent left temporal and cheek regions.

CONCLUSION

3D scanning effectively assesses facial asymmetry in clinical practice. Research indicates significant differences in asymmetry between the facial regions. Evaluating these differences pre-treatment can guide the selection of therapeutic methods to improve facial asymmetry.

LEVEL OF EVIDENCE

3 (Diagnostic).

Sex classification of 3D skull images using deep neural networks

Determining the fundamental characteristics that define a face as "feminine" or "masculine" has long fascinated anatomists and plastic surgeons, particularly those involved in aesthetic and gender-affirming surgery. Previous studies in this area have relied on manual measurements, comparative anatomy, and heuristic landmark-based feature extraction. In this study, we collected retrospectively at Cedars Sinai Medical Center (CSMC) a dataset of 98 skull samples, which is the first dataset of this kind of 3D medical imaging. We then evaluated the accuracy of multiple deep learning neural network architectures on sex classification with this dataset. Specifically, we evaluated methods representing three different 3D data modeling approaches: Resnet3D, PointNet++, and MeshNet. Despite the limited number of imaging samples, our testing results show that all three approaches achieve AUC scores above 0.9 after convergence. PointNet++ exhibits the highest accuracy, while MeshNet has the lowest. Our findings suggest that accuracy is not solely dependent on the sparsity of data representation but also on the architecture design, with MeshNet's lower accuracy likely due to the lack of a hierarchical structure for progressive data abstraction. Furthermore, we studied a problem related to sex determination, which is the analysis of the various morphological features that affect sex classification. We proposed and developed a new method based on morphological gradients to visualize features that influence model decision making. The method based on morphological gradients is an alternative to the standard saliency map, and the new method provides better visualization of feature importance. Our study is the first to develop and evaluate deep learning models for analyzing 3D facial skull images to identify imaging feature differences between individuals assigned male or female at birth. These findings may be useful for planning and evaluating craniofacial surgery, particularly gender-affirming procedures, such as facial feminization surgery.

Correction: The effect of sex and age on facial shape directional asymmetry in adults: A 3D landmarks-based method study

[This corrects the article DOI: 10.1371/journal.pone.0288702.].

Three-dimensional imaging evaluation of facial swelling after orthognathic surgery with compression and Kinesio taping therapy: a randomized clinical trial

Background

Postoperative swelling is a common complication of orthognathic surgery. The authors used three-dimensional (3D) image analysis and body surface temperature to determine the effects of compression taping (CT) and Kinesio taping (KT) by the epidermis, dermis, and fascia method (EDF-KT) on postoperative swelling.

Materials and methods

The authors conducted a prospective, parallel-group, randomized controlled trial. Among the 162 patients diagnosed with jaw deformity and who underwent orthognathic surgery from August 2020 to October 2022, 105 patients (men: 36, women: 69, mean age: 28.27±8.92) underwent Le Fort type I + sagittal split ramus osteotomy (SSRO) or SSRO and were included in this study. Patients were randomly divided into three groups: EDF-KT group (n=31), CT group (n=41), and no tape group (control group, n=30). All taping was performed immediately postoperatively and removed on postoperative day (POD) 5. Three-dimensional images of the participants' faces were obtained preoperatively and at PODs 3, 7, 30, and 90 using a hand-held 3D imaging system and infrared thermography.

Results

No significant difference was observed in postoperative swelling and postoperative body surface temperature between the groups at each time point. The CT group showed a trend towards reduced swelling on PODs 3 and 7 and a trend toward residual swelling on POD 90. The EDF-KT group showed a trend towards an increase in postoperative body surface temperature.

Conclusion

CT taping may not be appropriate for postoperative swelling control, suggesting that EDF-KT may affect body surface temperature. Further validation of the efficacy of KT for jaw deformities is needed.

Preoperative Eyelid and Eyebrow Asymmetry: A Potential Pre-Operation Inform Consent Option: A Descriptive Cross-Sectional Study

Background

We aimed to determine the prevalence of pre-existing asymmetry in our patients and investigate the impact of age and sex on upper facial asymmetry.

Methods

We collected images from 155 patients who were undergoing upper eyelid blepharoplasty and MRD1 (marginal reflex distance 1), TPS (tarsal plate show), and BFS (brow fat span) measurements were extracted by ImageJ software. The relationship between asymmetry and age and gender was assessed by comparing the mean differences of these metrics. A generalized linear model (GLM) was used to compare the outcomes of the study. P-value < 0.05 was considered significantly different in all tests.

Results

Pre-operative asymmetry was present in 112 (72%) patients. Among the cases, 61 (39%), 40 (26%), and 24 (15.5%) patients had more than 1mm of asymmetry in BFS, TPS, and MRD1, respectively. Males under 50 years old had the most asymmetry in the preorbital area. Comparing men under 50 years old with the other groups showed that the mean ± SD of absolute differences of TPS was significantly higher in this group (all P< 0.00), but pairwise comparison for MRD1 and BFS indicated no significant correlation between age, gender, and the mean asymmetry of these parameters (overall test P = 0.70 for MDR1 and P = 0.45 for BFS).

Conclusion

Most patients have asymmetry before surgery without being aware of it. Awareness of this asymmetry and the relationship between facial asymmetry and age and gender is essential to prevent dissatisfaction due to the probable post-operative asymmetry and unrealistic expectations.