Analysis of Facial Asymmetry

Integra's legacy unveiled: expert panel recommendations summarizing 25 years of experience in head and neck reconstruction

Background

Integra® Dermal Regeneration Template (IDRT) is used for its ability to facilitate wound closure and mimic various skin functions, marking a breakthrough in medical technology.

Methods

Through a synthesis of expert opinions, clinical experiences, and published evidence, this review sheds light on current applications of IDRT in head and neck wound care.

Results

This review covers the application of IDRT for post-oncological surgery reconstructions, trauma-induced injuries, and scar corrections. It focuses on the use of IDRT in specific anatomical regions (scalp, temporal, orbital, nasal areas, neck, and ears) and in pediatric and older patients. The economic aspects, including cost-effectiveness and value in the healthcare system, are also examined.

Conclusions

The insights presented aim to inform clinicians and encourage the broader integration of IDRT into clinical practice, enhancing patient outcomes in wound management.

Exploring craniofacial fluctuating asymmetry in a South African sample

Biological anthropologists have extensively investigated the relationship between fluctuating asymmetry (FA) and its association with population history and health. However, in South Africa, few studies have been done on skeletal asymmetry and its potential impact on anthropological analyses. The study aimed to examine craniofacial asymmetry within a contemporary South African population, specifically focusing on the association between FA, sex, and population affinity. The sample consisted of cranial micro-focus X-ray computed tomography scans (micro-XCT) from 115 adult individuals. Craniometric landmarks were placed and used to calculate inter-landmark distances (ILDs) to assess size variation, and geometric morphometric methods (GMMs) were performed to assess asymmetrical shape variation. Additionally, two indices assessing FA (FA8 and FA17) were calculated from the left and right ILDs to further explore patterns of asymmetry for various regions of the cranium. Asymmetry was particularly apparent in females and black South Africans, which is consistent with reports in the literature. Significant levels of FA were noted in the nasal and temporal regions, more so for shape than size. While asymmetry potentially may have a minimal influence on biological profile estimations based on craniometry, biological anthropologists should have an understanding of the consequences asymmetry may have on skeletal elements or traits being employed on an individual basis.

Comparison of Mirroring and Overlapping Analysis and Three-Dimensional Soft Tissue Spatial Angle Wireframe Template in Evaluating Facial Asymmetry

AIM

The purpose of this study was to evaluate the accuracy and efficacy of a new wireframe template methodology in analyzing three-dimensional facial soft tissue asymmetry.

MATERIALS AND METHODS

Three-dimensional facial soft tissue data were obtained for 24 patients. The wireframe template was established by identifying 34 facial landmarks and then forming a template on the face with the MeshLab 2020 software. The angle asymmetry index was automatically scored using the template. The mirroring and overlapping technique is accepted as the golden standard method to diagnose facial asymmetry by acquiring deviation values of one's face. Consistency rates between the two methodologies were determined through a statistical comparison of the angle asymmetry index and deviation values.

RESULTS

Overall consistency rates in the labial, mandibular angle, cheek, chin, and articular regions were 87.5%, 95.8%, 87.5%, 91.7%, and 100%, respectively. Regions with consistency rates in three dimensions of more than 85% are the x-axis and the z-axis of all regions and the y-axis of the mandibular angle, chin, and articular region.

CONCLUSIONS

Soft tissue facial asymmetry can be diagnosed accurately and effectively by using a three-dimensional soft tissue spatial angle wireframe template. Precise localization of asymmetry can be offered, and indiscernible tiny asymmetry can be identified.

Automatic soft-tissue analysis on orthodontic frontal and lateral facial photographs based on deep learning

BACKGROUND

To establish the automatic soft-tissue analysis model based on deep learning that performs landmark detection and measurement calculations on orthodontic facial photographs to achieve a more comprehensive quantitative evaluation of soft tissues.

METHODS

A total of 578 frontal photographs and 450 lateral photographs of orthodontic patients were collected to construct datasets. All images were manually annotated by two orthodontists with 43 frontal-image landmarks and 17 lateral-image landmarks. Automatic landmark detection models were established, which consisted of a high-resolution network, a feature fusion module based on depthwise separable convolution, and a prediction model based on pixel shuffle. Ten measurements for frontal images and eight measurements for lateral images were defined. Test sets were used to evaluate the model performance, respectively. The mean radial error of landmarks and measurement error were calculated and statistically analysed to evaluate their reliability.

RESULTS

The mean radial error was 14.44 ± 17.20 pixels for the landmarks in the frontal images and 13.48 ± 17.12 pixels for the landmarks in the lateral images. There was no statistically significant difference between the model prediction and manual annotation measurements except for the mid facial-lower facial height index. A total of 14 measurements had a high consistency.

CONCLUSION

Based on deep learning, we established automatic soft-tissue analysis models for orthodontic facial photographs that can automatically detect 43 frontal-image landmarks and 17 lateral-image landmarks while performing comprehensive soft-tissue measurements. The models can assist orthodontists in efficient and accurate quantitative soft-tissue evaluation for clinical application.

Comparison of Different 3D Surface Registration-Based Methods to Assess Facial Asymmetry

BACKGROUND/OBJECTIVES

Facial asymmetry is gaining an increasing diagnostic interest in many clinical contexts. Several three-dimensional surface-based methods have been proposed for its assessment; however, they might provide non-equivalent data. Since there is a lack of comparative studies in these terms, this study aims to compare three methods for assessing the asymmetry of the face and facial thirds, thus addressing whether the potential differences can be considered clinically acceptable or not.

METHODS

Two 'maxillofacial' methods based on the trigeminal nerve distribution and one 'orthodontic' method based on reference horizontal planes were used to identify the facial thirds on 3D facial models of 80 Italian healthy adults to calculate the asymmetry of the face, and the upper, middle, and lower thirds of the face differently selected by each method. As a measure of asymmetry, the Root Mean Square value was calculated through a mirroring surface-based registration. Intra- and inter-operator reliability was verified for each method. Differences and interchangeability between the methods were tested, respectively, by two-way repeated measures ANOVA (Analysis of Variance) and Bland-Altman and Similarity Percentage model analysis. Additionally, the time required to perform each method was assessed.

RESULTS

All methods demonstrated excellent intra- and inter-operator reliability. While the ANOVA analysis found significant differences (p < 0.001) for the majority of facial Regions of Interest between each method, the Bland-Altman analysis revealed that the differences were clinically acceptable (<0.50 mm) for all facial regions between the trigeminal methods, and for the face and the upper third of the face between the orthodontic method, which was revealed to be faster, and the trigeminal ones. The additional similarity percentage model provided visual support for the complete interchangeability of the two trigeminal methods, as evidenced by the lower Coefficient of Variation value.

CONCLUSIONS

There is no best method for assessing facial asymmetry that applies to all types of clinical settings, as we have shown that different methods may not be completely interchangeable. However, we suggest that the methods based on the trigeminal subdivision can be used interchangeably in contexts where the morpho-functional analysis of maxillofacial regions with different embryological origins is considered. Thus, the clinical setting imposes the choice of one method over another and, as we have pointed out, the consequent comparison of data with those obtained with methods whose interchangeability has been demonstrated.

Influence of dental midline deviation with respect to facial flow line on smile esthetics-A cross-sectional study

BACKGROUND/OBJECTIVE

A contemporary concept states that dental midline deviation towards the direction of facial flow line (FFL) can mask the compromised smile esthetics. This study aimed to identify a range of midline deviations that can be perceived towards or away from the FFL influencing smile esthetics.

MATERIALS AND METHODS

A cross-sectional study was conducted using a frontal smile photograph of an adult female. The photograph was altered on Adobe Photoshop software into six different photographs by deviating the dental midlines towards and away from the FFL. A constant deviation of chin towards the left side was incorporated in all the photographs. Forty-three laypersons (LP) and dental professionals (DPs) evaluated those photographs. Independent t-test was used to compare the perception of dental midline deviation between LP and DPs. Simple linear regression was run to identify the factors associated with the scoring.

RESULTS

A statistically significant difference was observed for picture two with 4 mm towards FFL in the perception of midline deviation between LP and DPs. LP could not perceive the midline deviations up to 4 mm while DPs were able to perceive deviations above 2 mm. The greater the age the better the scores were and female raters had a greater inclination towards poor scores.

CONCLUSIONS

From 2 to 4 mm of midline deviation towards the FFL can be tolerated by LP and DPs.

CLINICAL SIGNIFICANCE

These findings underscore the importance of considering facial symmetry in orthodontic and cosmetic dental treatments to optimize smile esthetics.

Accuracy of the Conventional Facial Impression Method and Three-Dimensional Auricular Shape Data Obtained Using Extra- and Intraoral Optical Scanners

Background: Facial impression methods have been used to fabricate auricular prostheses; however, deformation due to the weight of the impression material remains. This study aimed to investigate the accuracy of auricular three-dimensional (3D) data obtained using a 3D optical extraoral scanner and an intraoral scanner compared with that of a conventional facial impression method. Methods: Six auricles were digitized using an extraoral scanner with and without a reference board around the auricle and an intraoral scanner. Auricle casts fabricated using auricle impressions were scanned using a laboratory scanner. All obtained data were superimposed, and the 3D deformations of the different methods were evaluated using measurement mapping and root mean square (RMS) values. The length, width, and height of the auricular casts and scanned data were measured and compared with the sizes of the original auricles measured using a caliper. Results: Large displacements of the back and margins of the ears were observed, and the RMS values ranged from 0.5-2.4 mm. Larger widths and smaller heights of the scanned and impression data were observed compared to the anthropometric ear data. Conclusions: The study concluded that the fabrication of auricular prostheses using optical scanning is clinically acceptable. All examined scanning techniques demonstrated discrepancies within acceptable limits when compared to the conventional facial impression method.

Measuring the esthetic outcome using a three-dimensional facial scanner after parotidectomy and application of vascularized fat flaps

BACKGROUND

Parotidectomy can affect facial symmetry. Our study evaluated the symmetry of different facial areas and upper neck after total parotidectomy and filling the area with vascularized fat flap (VFF).

METHODS

Facial symmetry was evaluated in eight patients and a control group matched in terms of gender and age, using a three-dimensional (3D) facial scanner. The operated side was compared with the non-operated side and the symmetry compared with that of the control group. Scanning was performed either within the first year (group 1; n = 5) or after 3 years (group 2; n = 3) postoperatively.

RESULTS

The patients' cheek and neck areas were found to be significantly more asymmetric, but the cheek area in group 2 was significantly more symmetrical when compared with group 1.

CONCLUSION

VFF appeared to achieve similar facial symmetry to the matched non-operated group. Time had a positive impact on the facial symmetry. The neck area was the most asymmetric, and proved to be unreliable, regardless of whether any procedure was performed or not.

A method for accuracy of placement analysis on radiolucent polyether-ether-keton facial implants: A case series

Facial asymmetry is defined as a bilateral difference between facial components. Correction, often desired by the patient, can be performed with the aim of bone born patient-specific solid implants designed using 3D CAD software. This treatment is embedded in the daily practice of today's healthcare. However, an analysis of the implant's accuracy of placement has not been reported. This case series describes the accuracy analysis of bone born aesthetic facial implants manufactured out of polyether-ether-ketone (PEEK). The accuracy analysis was based on postoperative (cone beam) computed tomography ((CB)CT) data and preoperative 3D planning. The analysis showed a median entry point error of 0.7 mm (min: 0.1, max: 3.3, interquartile range: 0.78). The median maximal orientation error was 5.5° (min: 0.1, max: 36.8, interquartile range: 7.13). Both parameters showed an excellent intraobserver and interobserver agreement with an ICC above 0.84. The described cases show that the analysis method is an objective approach for determining the accuracy of PSI placement and indicates that these implants can be placed accurately on the osseous face.

Cranial fluctuating asymmetry and its relationship with non-specific physiological stress indicators in a contemporary South African cadaveric skeletal sample

OBJECTIVES

Biological anthropologists frequently explore skeletal asymmetry, together with population health and disease. Given the conflicting findings in existing literature, this study aimed to clarify whether an association exists in a South African sample.

MATERIALS

Dry bone and cranial micro-focus X-ray Computed Tomography (micro-XCT) scans of 115 South African individuals were assessed.

METHODS

Fluctuating asymmetry (FA) indices were calculated from interlandmark distances, and the frequency of four types of non-specific signs of physiological stress were documented to explore the relationship between FA and disease.

RESULTS

Black South Africans did not exhibit a high FA index; however, they had the highest prevalence of non-specific signs of physiological stress. However, no significant correlations were detected between FA indices and pathological lesions.

CONCLUSION

No correlation was observed between FA and populations from different socio-economic backgrounds. However, individuals of lower socio-economic status (SES) demonstrated a greater prevalence of non-specific signs of physiological stress.

SIGNIFICANCE

This research suggests that skeletal indicators of stress may be a suitable biological marker for assessing differences in SES among population groups, while indicating that levels of cranial FA is an inadequate biological marker.

LIMITATIONS

Possible limitations may include measurement error, and the lack of information on the life history and medical records of individuals in this sample.

SUGGESTIONS FOR FURTHER RESEARCH

Future research should include a larger sample with more South African groups, and should evaluate the potential association among age, FA, and expression of skeletal markers of disease.

Digital Planning to Enhance Diagnosis and Precision in Correcting Excessive Gingival Display in the Presence of Asymmetrical Maxillary Position: A Case Report

This case report addresses the treatment of excessive gingival display (EGD) in the context of maxillary asymmetry, zenith irregularities, and occlusal plane inclination. Digital planning was pivotal in formulating a precise treatment strategy by incorporating facial photographs, digital models, and cone-beam computed tomography data. Parameters, including occlusal plane inclination, teeth position, and lip-to-gingival margin relationships, were considered to ensure treatment alignment with the patient's facial characteristics. Notably, during the planning phase, it was evident that the conventional approach using the cementoenamel junction as the apical limit for incisions would result in asymmetry. Consequently, the gingival margin position was defined in accordance with facial and lip features. The chosen treatment, flapless crown lengthening, was tailored to the patient's thin phenotype and guided by measurements derived from digital planning. Postsurgery, the patient experienced a swift and painless recovery. A harmonious smile with a stable gingival margin position was achieved at the 1-year follow-up, seamlessly complementing the patient's facial attributes. This case underscores the importance of personalized EGD treatment and the value of digital planning in enhancing diagnostic accuracy and precise treatment planning, ultimately facilitating optimal treatment strategies.

The Asymmetry Within: A Renewed Look at Cupids Bow in Unilateral Cleft Lip

The purpose of this study is to analyze the angular variations within Cupid's bow in patients with unoperated unilateral cleft lip (UCL). Angular features of Cupid's bow were quantified in standardized presurgical photographs of children with UCL by 5 medical professionals specializing in craniofacial anomalies. The peaks and valley of Cupid's bow were identified. A cleft side (CSA) and a noncleft side angle (NCSA) were delineated and measured by each expert. The data was pooled, and the angles were analyzed for symmetry. Cupid's bow asymmetry was defined as a difference between NCSA and CSA ≥3°. Of the 37 patients studied, 29 were found to have asymmetry of Cupid's bow with an average angle difference of 8.0° (95% CI: 6.6°-9.5°). Within this group,15 patients were found with acute asymmetry and 14 with obtuse asymmetry. Geometric analysis was performed on an example of a patient with acute asymmetry to demonstrate how correction of asymmetry can be considered during surgical repair. There is an asymmetry that exists in the Cupid's bow of a significant number of patients with unoperated UCL. This finding not only adds to our understanding of UCL but may also have important implications when selecting the method/technique of surgical repair.

3D facial mask for facial asymmetry diagnosis

Objectives

Facial asymmetry is a common problem seen in orthodontic clinics that may affect patient esthetics. In some instances, severe asymmetry that affects patient esthetics may cause psychological issues. An objective method is therefore required to help orthodontists identify asymmetry issues.

Materials and methods

We used three-dimensional (3D) facial images and landmark-based anthropometric analysis to construct a 3D facial mask to evaluate asymmetry. The landmark coordinates were transformed using a symmetric 3D face model to evaluate the efficacy of this method. Patients with facial asymmetry were recruited to conduct mirror and overlap analysis to form color maps, which were used to verify the utility of the novel soft tissue landmark-based method.

Results

The preliminary results demonstrated that the asymmetry evaluation method had a similar response rate compared to diagnosis using mirror and overlap 3D images, and could therefore identify 3D asymmetry problems.

Conclusions

By using 3D facial scans and 3D anthropometric analysis, we developed a preliminary evaluation method that provides objective parameters to clinically evaluate patient facial asymmetry and aid in the diagnosis of asymmetric areas.

Clinical relevance

This study presents a novel facial asymmetry diagnostic method that has the potential to aid clinical decisions during problem identification, treatment planning, and efficacy evaluation.

Are Craniofacial Asymmetries Related to Trunk Asymmetries?

OBJECTIVE

The aim of this study was to investigate whether craniofacial asymmetries could be a predictor of spine asymmetries or not.

METHODS

Female individuals aged between 18 and 25 years participated in this cross-sectional descriptive-analytic study. The angle of trunk rotation was measured by a scoliometer in conjunction with the Adams forward-bending test. Individuals in the control group (n = 57) had spinal curvature of 0 to 3 degrees, and individuals in the study group (n = 53) had spinal curvature of between 4 and 6 degrees. Facial anthropometric measurements of individuals were evaluated by referencing anatomical landmarks determined on the face with 2-dimensional photogrammetry using ImageJ (Version 1.53q) program.

RESULTS

Both groups were similar in terms of facial measurements (P > 0.05). Axial trunk rotation values of the mid-thoracic and thoraco-lumbar regions were significantly higher on both sides of the asymmetry group (P < 0.05). The distances between facial landmarks are not associated with asymmetries of spine regions (P > 0.05).

CONCLUSION

Although the sensitivity and predictive value of facial asymmetries in determining trunk asymmetries and sagittal spinal posture were low, it was concluded that comparative studies are needed, especially in individuals with asymmetry at the level of scoliosis, as the asymmetries of the individuals in our study were not at the level of scoliosis.

Effects of the Mandibular Functional Units and Soft Tissue on Facial Asymmetry

Mandibular asymmetry has a variety of patterns because they are affected the position and the shape of mandible in addition to the overlying soft tissue. This study aimed to assess the factor in mandibular asymmetry, focusing on each mandibular functional units and the soft tissue thickness in the mandibular angle area. Forty patients who were diagnosed with facial asymmetry and undergone the orthognathic surgery without genioplasty were enrolled in this study. The skeletal patterns of the patients were analyzed by using cone-beam computed tomography data and 3D virtual images divided into 2 categories; the mandibular functional unit length and the soft tissue depth. All difference in bilateral mandibular functional unit lengths had a statistically significant with chin top deviation ( P <0.05). The greatest correlation was the condylar unit length compared with other functional units. The soft tissue thickness in the mandibular angle area was not statistically related to chin top deviation ( P >0.05), and the soft tissue did not change remarkably after orthognathic surgery ( P >0.05). This study suggests that the considerations of a surgical plan for treatment based on the mandibular asymmetry.

The Accuracy and Stability of Intentional Change of Frontal-Ramal Inclination in Orthognathic Surgery for Facial Asymmetry Patients

Facial asymmetry can be defined as differences in the left and right sides of the face, and most of the patients with facial asymmetry have different left and right frontal-ramal inclinations (FRIs). Restoring the symmetry of both FRIs is important in the surgery of facial asymmetry patients, but it is very difficult to achieve perfect symmetry through conventional orthognathic surgery. However, by using 3-dimensional (3D) virtual planning and CAD/CAM technolo gies, intentional change of FRIs can be possible so the symmetry can be improved. The purpose of this study is to evaluate the surgical accuracy and long-term stability of intentional change of FRIs by 3D virtual surgery, CAD/CAM-assisted orthognathic surgery for patients with facial asymmetry. The study included 20 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2019 to December 2021. To evaluate the accuracy of surgery, 3D facial cone beam computed tomography (CBCT) taken immediately after surgery (T1) and virtual surgery data (Tv) were measured and the difference values were calculated. The evaluation of the long-term stability of intentional change of FRI was performed by measuring T1 and T2 (3D facial cone beam computed tomography images taken 6 mo after surgery) and the difference values were calculated. The difference values of FRIs in the left and right proximal segments of each patient were calculated. And then, for comparison depending on the direction of rotation, increased FRI groups (n=20, medial rotation) and decreased FRI groups (n=20, lateral rotation) were analyzed separately. As a result, all difference values at both (ΔT1-Tv) and (ΔT2-T1) were <1 degree. As a result of analyzing the entire FRI by dividing it into decreasing and increasing groups, the mean value of (ΔT1-Tv) was 0.225 degrees for the decreasing group and 0.275 degrees for the increasing group. It means that the proximal segment moved less than the movement implemented by the virtual surgery through actual surgery but it shows a very small error, which means that the overall operation almost accurately implements the virtual surgical planning. Compared with (ΔT1-Tv), the mean value of (ΔT2-T1) showed a much smaller error value, and no specific tendency was observed. This indicates that the stability after surgery is very good. Based on this study, using 3D virtual surgery planning and CAD/CAM technologies for treating patients with facial asymmetry was very useful, and surgery could be performed accurately and predictably. In particular, left-right symmetry was almost perfectly achieved through virtual simulation and could be implemented through actual surgery. Therefore, it can be said that the use of these 3D technologies is recommended for the surgical approach of facial asymmetry.

A Face to Love or Trust

This article demonstrates the use of a card sorting game that is suitable for field studies. Subjective judgment in face perception is studied by sorting faces based on attractiveness or trustworthiness. Are beautiful people also trustworthy, or does beauty come with a price? Our first hypothesis is that the two conditions like and trust are different. We investigate this using a sorting game, where participants are asked to sort 27 semi-artificial portraits according to how much they like or trust the faces. The faces are in two different conditions: prototypes and individualized prototypes. Our participants were consistent in their judgments. Participants claim to have reacted to small inconsistencies in facial expressions in the trust condition, and we investigate the relation to anatomical features using a model and Correspondence Analysis.

Development of a Cranial Suture Traction Therapy Program for Facial Asymmetry Correction Using the New Delphi Technique

Background and Objectives: We aimed to develop a cranial suture traction therapy program, a non-surgical therapeutic method for facial asymmetry correction. Materials and Methods: Six experts, including rehabilitation medicine specialists, oriental medical doctors, dentistry specialists, five experts, including Master’s or doctoral degree holders in skin care and cosmetology with more than 10 years of experience in the field, 4 experts including educators in the field of skin care, a total of 15 people participated in the validation of the development of the cranial suture traction therapy program in stages 1 to 3. Open questions were used in the primary survey. In the second survey, the results of the first survey were summarized and the degree of agreement regarding the questions in each category was presented. In the third survey, the degree of agreement for each item in the questionnaire was analyzed statistically. Results: Most of the questions attained a certain level of consensus by the experts (average of ≥ 4.0). The difference between the mean values was the highest for the third survey at 0.33 and was the lowest between the second and third surveys at 0.47. The results regarding the perceived degree of importance for each point of the evaluation in both the second and third stages of the cranial suture traction therapy program were verified using the content validity ratio. The ratio for the 13 evaluation points was within the range of 0.40−1.00; thus, the Delphi program for cranial suture traction therapy verified that the content was valid. Conclusions: As most questions attained a certain level of consensus by the experts, it can be concluded that these questions are suitable, relevant, and important. The commercialization of the cranial suture traction treatment program will contribute to the correction and prevention of facial dislocations or asymmetry, and the developed treatment will be referred to as cranial suture traction therapy (CSTT).

Reinforcement learning coupled with finite element modeling for facial motion learning

BACKGROUND AND OBJECTIVE

Facial palsy patients or patients with facial transplantation have abnormal facial motion due to altered facial muscle functions and nerve damage. Computer-aided system and physics-based models have been developed to provide objective and quantitative information. However, the predictive capacity of these solutions is still limited to explore the facial motion patterns with emerging properties. The present study aims to couple the reinforcement learning and the finite element modeling for facial motion learning and prediction.

METHODS

A novel modeling workflow for learning facial motion was developed. A physically-based model of the face within the Artisynth modeling platform was used. Information exchange protocol was proposed to link reinforcement learning and rigid multi-bodies dynamics outcomes. Two reinforcement learning algorithms (deep deterministic policy gradient (DDPG) and Twin-delayed DDPG (TD3)) were used and implemented to drive the simulations of symmetry-oriented and smile movements. Numerical outcomes were compared to experimental observations (Bosphorus database) for evaluation and validation purposes.

RESULTS

As result, after more than 100 episodes of exploring the environment, the agent starts to learn from previous trials and can find the optimal policy after more than 300 episodes of training. Regarding the symmetry-oriented motion, the muscle excitations predicted by the trained agent help to increase the value of reward from R = -2.06 to R = -0.23, which counts for ∼89% improvement of the symmetry value of the face. For smile-oriented motion, two points at the edge of the mouth move up 0.35 cm, which is within the range of movements estimated from the Bosphorus database (0.4 ± 0.32 cm).

CONCLUSIONS

The present study explored the muscle excitation patterns by coupling reinforcement learning with a detailed finite element model of the face. We developed, for the first time, a novel coupling scheme to integrate the finite element simulation into the reinforcement learning process for facial motion learning. As perspectives, this present workflow will be applied for facial palsy and facial transplantation patients to guide and optimize the functional rehabilitation program.

Facial Asymmetry: A Narrative Review of the Most Common Neurological Causes

Symmetry of the face is one of the most important features for the perception of attractiveness. Asymmetry of the face means that the right and left sides of the face are not identical. Subclinical facial asymmetry is very common in the general population. Most people have some slight facial asymmetry, and this is the normal biological situation in humans. Abnormalities from soft tissue, dental, and skeletal elements lead to facial asymmetry. Asymmetry has many causal factors, and its aetiology includes both congenital and acquired conditions. Neurological facial asymmetry is scarcely addressed in the dental literature. In this narrative review, we focus on the most common neurological causes of facial asymmetry. From a neurological point of view, facial asymmetry can result from disturbances of the cranial nerves, developmental disorders, or myopathies. In the broad range of differential diagnostics of facial asymmetry, neurological abnormalities should be taken into consideration. The treatment must be related to the underlying cause. Complete knowledge of the aetiological factors and the character of the asymmetry plays a crucial role in formulating a treatment plan.

Three-dimensional assessment of facial asymmetry in Class III subjects. Part 1: a retrospective study evaluating postsurgical outcomes

OBJECTIVE

The present study aimed to determine the site and severity of maxillomandibular asymmetry before and after orthognathic surgery in asymmetric patients.

MATERIALS AND METHODS

Presurgery and postsurgery cone beam computed tomography (CBCT) data of 21 facial asymmetry patients (7 males and 14 females, mean age: 23.0 ± 3.36 years) with soft tissue chin deviation ≥ 3 mm who had undergone bimaxillary surgery were evaluated. Seven midline and twenty bilateral hard tissue landmarks were identified for the evaluation of facial asymmetry and outcomes were assessed against age- and gender-matched control subjects.

RESULTS

In the asymmetry group, bilateral landmarks exhibited significant deviation in the mandible and midface regions. Before surgery, asymmetry was more severe at the mandibular midline and sites close to it, in the asymmetry group. Bimaxillary surgery proved to be highly effective, with a significant correction of the menton to a clinically normal value (2.90 mm, p < 0.001). After surgery, significant residual asymmetry was observed at the mental foramen (p = 0.001) in the R-L direction. Moreover, significant asymmetry persisted at the sigmoid notch (p = 0.001) in the S-I direction.

CONCLUSIONS

Mandibular midline landmarks and chin peripheral regions contribute significantly to overall facial asymmetry characteristics. Despite significant correction after bimaxillary surgery, asymmetry persisted at several sites, thereby requiring secondary correction. Comprehensive 3D presurgical planning is central for asymmetry correction in a single surgery.

CLINICAL RELEVANCE

The present study specifies the location of residual asymmetry sites and advocates the correction of those sites during initial surgery.

The Vectra M3 3-dimensional digital stereophotogrammetry system: A reliable technique for detecting chin asymmetry

Purpose

The aim of this study was to evaluate the reliability of the Vectra M3 (3D Imaging System; Canfield Scientific, Parsippany, NJ, USA) in detecting chin asymmetry, and to assess whether the automatic markerless tracking function is reliable compared to manually plotting landmarks.

Materials and Methods

Twenty subjects (18 females and 2 males) with a mean age of 42.5±10.5 years were included. Three-dimensional image acquisition was carried out on all subjects with simulated chin deviation in 4 stages (1-4 mm). The images were analyzed by 2 independent observers through manually plotting landmarks and by Vectra software auto-tracking mode. Repeated-measures analysis of variance and the Tukey post-hoc test were performed to evaluate the differences in mean measurements between the 2 operators and the software for measuring chin deviation in 4 stages. The intraclass correlation coefficient (ICC) was calculated to estimate the intra- and inter-examiner reliability.

Results

No significant difference was found between the accuracy of manually plotting landmarks between observers 1 and 2 and the auto-tracking mode (P=0.783 and P=0.999, respectively). The mean difference in detecting the degree of deviation according to the stage was <0.5 mm for all landmarks.

Conclusion

The auto-tracking mode could be considered as reliable as manually plotted landmarks in detecting small chin deviations with the Vectra® M3. The effect on the soft tissue when constructing a known dental movement yielded a small overestimation of the soft tissue movement compared to the dental movement (mean value<0.5 mm), which can be considered clinically non-significant.

[Preliminary clinical application verification of complete digital workflow of design lips symmetry reference plane based on posed smile]

OBJECTIVE

To automatically construct lips symmetry reference plane (SRP) based on posed smile, and to evaluate its advantages over conventional digital aesthetic design.

METHODS

Eighteen subjects' three-dimensional facial and dentition data were gathered in this study. The lips SRP of experimental groups were used with the standard weighted Procrustes analysis (WPA) algorithm and iterative closest point (ICP), respectively. A reference plane defined by experts based on regional ICP algorithm, served as the truth plane. The angle error values between the lips SRP of WPA algorithm in the experimental groups and the truth plane were evaluated in this study, and the lips SRP of ICP algorithm of the experimental groups was calculated in the same way. The lips SRP based on posed smile as a reference for aesthetic design and evaluate preliminary clinical application.

RESULTS

The average angle error between the lips SRP of WPA algorithm and the truth plane was 1.78°±1.24°, which was smaller than that between the lips SRP of ICP and the truth plane 7.41°±4.31°. There were significant differences in the angle errors among the groups (P < 0.05). In the aesthetic design of anterior teeth, automatically constructing the lips SRP of WPA algorithm based on posed smile and the original symmetry plane by re-ference compared with the prosthetic design, the subjects' scores on the lips SRP of WPA algorithm based on posed smile (8.48±0.57) were higher than those on the original symmetry plane (5.20±1.31).

CONCLUSION

Automatically constructing the lips SRP of WPA algorithm based on posed smile was more accurate than ICP algorithm, which was consistent with the truth plane. Moreover, it can provide an important reference for oral aesthetic diagnosis and aesthetic analysis of the restoration effect. In the aesthetic design of anterior teeth, automatically constructing the lips SRP of WPA algorithm based on posed smile can improve the patients' satisfaction in esthetic rehabilitation.

[Preliminary clinical application verification of complete digital workflow of design lips symmetry reference plane based on posed smile]

OBJECTIVE

To automatically construct lips symmetry reference plane (SRP) based on posed smile, and to evaluate its advantages over conventional digital aesthetic design.

METHODS

Eighteen subjects' three-dimensional facial and dentition data were gathered in this study. The lips SRP of experimental groups were used with the standard weighted Procrustes analysis (WPA) algorithm and iterative closest point (ICP), respectively. A reference plane defined by experts based on regional ICP algorithm, served as the truth plane. The angle error values between the lips SRP of WPA algorithm in the experimental groups and the truth plane were evaluated in this study, and the lips SRP of ICP algorithm of the experimental groups was calculated in the same way. The lips SRP based on posed smile as a reference for aesthetic design and evaluate preliminary clinical application.

RESULTS

The average angle error between the lips SRP of WPA algorithm and the truth plane was 1.78°±1.24°, which was smaller than that between the lips SRP of ICP and the truth plane 7.41°±4.31°. There were significant differences in the angle errors among the groups (P < 0.05). In the aesthetic design of anterior teeth, automatically constructing the lips SRP of WPA algorithm based on posed smile and the original symmetry plane by re-ference compared with the prosthetic design, the subjects' scores on the lips SRP of WPA algorithm based on posed smile (8.48±0.57) were higher than those on the original symmetry plane (5.20±1.31).

CONCLUSION

Automatically constructing the lips SRP of WPA algorithm based on posed smile was more accurate than ICP algorithm, which was consistent with the truth plane. Moreover, it can provide an important reference for oral aesthetic diagnosis and aesthetic analysis of the restoration effect. In the aesthetic design of anterior teeth, automatically constructing the lips SRP of WPA algorithm based on posed smile can improve the patients' satisfaction in esthetic rehabilitation.

[Diagnostic and treatment alternatives for the correction of facial asymmetries: a literature review]

Facial symmetry refers to a complete coincidence of each facial component on the sagittal plane, while asymmetry refers to the bilateral difference between these components. The presence of perfect bilateral symmetry is almost never present in human, so it is more common for individuals to predominate facial asymmetry. However, this condition can result from functional and esthetic problems. This research seeks to determine the alternatives, diagnosis and ideal treatment plan for the correction of each type of facial asymmetry through orthognathic surgery. For this purpose, a review of articles published between 2015 to date was carried out. Selecting those that were focused on describing or evaluating facial and dentofacial symmetry and asymmetry, type of diagnosis or treatment plan, including clinical cases. The Google search engine, SciELO and databases of medical interest, such as PubMed, PMC and Medigraphic were used. According to the research and treatments carried out during the last few years in the dental clinic, it has been proven that orthognathic treatment accompanied by previous planning is the best option for the management of skeletal facial asymmetries.

The Effect of Orthognathic Surgery on Changes in Masticatory Muscle Volume in Patients With Facial Asymmetry

ABSTRACT

The masseter muscle changes remarkably with orthognathic surgery and has a marked influence on the contours of the lower face. If the postoperative volume change of masticatory muscles, including the masseter muscles, can be predicted, it will facilitate preoperative planning and outcome prediction. This study investigated the association of masticatory muscle volume according to the presence or absence of facial asymmetry, and evaluated whether the volume of masticatory muscles, including that of the masseter muscle, changes after orthognathic surgery in facial asymmetry patients.Twenty patients who underwent LeFort I osteotomy and bilateral sagittal segmentation ramus osteotomy (BSSRO) with facial asymmetry between 2011 and 2017 were assigned to the asymmetric group. Additionally, 207 patients with a simple nasal fracture between 2016 and 2019 were included as the common group. Three-dimensional computed tomography images were retrospectively analyzed and compared between the asymmetric group and common group.The volume of both temporal and masseter muscles differed according to facial asymmetry, with the asymmetry in the muscle volume increasing in proportion to the degree of facial asymmetry. The difference in masseter volume on the shortened and lengthened sides was significantly reduced after orthognathic surgery, but a difference of about 1 cm3 remained. Additionally, the masticatory muscle volume on the lengthened side tended to be decreased more than that on the shortened side.Consideration of the postoperative change in the volume of the masticatory muscles may be helpful in planning orthognathic surgery in facial asymmetry patients.

Evaluation of an automated approach for facial midline detection and asymmetry assessment: A preliminary study

OBJECTIVE

To examine the level of agreement between the conventional method and a machine-learning approach to facial midline determination and asymmetry assessment.

SETTINGS AND SAMPLE POPULATION

The study included a total of 90 samples (53 females; 37 males) with different levels of mandibular asymmetry.

MATERIALS AND METHODS

Two researchers placed predefined soft tissue landmarks individually on selected facial frontal photographs and created 10 reference lines. The midsagittal line was determined as perpendicular to the midpoint of the bipupillary line, and the same two reference lines and facial landmarks were automatically determined by the software using machine-learning algorithms, and researchers created the other 8 reference lines using the facial landmarks that were determined automatically by the software. In the following stage, 2 linear and 10 angular measurements were made by a single researcher on 270 photographs, and the consistency and differences between the measurements were evaluated with a one-sample t test, an intraclass correlation coefficient (ICC) and Bland-Altman Plots.

RESULTS

The level of agreement of measurements between the researchers and the software was low for eight parameters (ICC˂0.70). The one-sample t test revealed that differences between the software and researcher measurements of lip canting and pronasale deviation were not statistically significantly different (P > .05). Aside from the body inclination difference in Group 3 (samples with a mandibular body inclination difference >6°), there was no clinically significant difference (˂3°) between the measurements of the two methods.

CONCLUSIONS

Machine-learning algorithms have the potential for clinical use in asymmetry assessment and midline determination and can help clinicians in a manual approach.

Studying factors influencing facial developmental instability

BACKGROUND

Developmental instability is a component of non-genetic variation that results from random variation in developmental processes. It is considered a sensitive indicator of the physiological state of individuals. It is reflected in various ways, but in this study we focussed on its reflection in fluctuating asymmetry (FA) and morphological integration.

AIM

To assess how, if at all, variations of facial morphology mirror developmental instability across childhood with respect to sex, growth rate and socioeconomic/environmental factors.

SUBJECTS AND METHODS

A set of 210 three-dimensional facial models (of children aged between 6.3 and 14.3 years) originating from the FIDENTIS 3D Face Database was subjected to landmark-based methods of geometric morphometrics to quantify the degree of facial asymmetry and facial morphological integration. In addition, the association with age, sex, and socioeconomic factors was assessed.

RESULTS

Our results showed a nonlinear increase of FA with age up to the age of 14 years. The pattern of sex-related variants in facial FA differed in relation to age, as girls exhibited higher values of FA than boys up to the age of 9 years. We found that a signal of modularity based on functional demands and organisation of the face is of particular importance. Here, girls exhibited higher morphological covariation among modules. During more rapid adolescence-related growth, however, covariation among modules at the asymmetrical level decreased in both sexes.

CONCLUSION

We can conclude that facial morphology was shown to be strongly integrated, particularly until adolescence. This covariation can facilitate an increase of FA. In addition, the results of this study indicate there is a weak association between socioeconomic stress and facial asymmetries. In contrast, sex and growth rate are reflected in developmental instability.

Expert consensus on the facial rejuvenation using the Mint Lift® in Koreans: Perspectives of plastic surgeons

BACKGROUND

It would be mandatory for plastic surgeons to consider anthropometric and anatomical differences between Asians and Caucasians in performing facial rejuvenation procedures using absorbable threadlifts in Asians.

METHODS

A consensus meeting was convened to discuss indications, treatment procedures, possible combination treatments, clinical outcomes, and safety of an absorbable polydioxanone (PDO) monofilament threadlift (Mint Lift® ; HansBiomed Co. Ltd., Seoul, Korea), for which the "Mint Aesthetics Expert Group" was organized with four Korean board-certified specialists in plastic and reconstructive surgery.

RESULTS

Our recommendations are as follows: First, the entry and exit points should be determined considering anatomical characteristics of the face (Level of evidence III). Second, treatment procedures may vary depending on indications (Level of evidence III). Third, short-term efficacy and safety of facial rejuvenation using the Mint Lift® have been well documented (Level of evidence I and III). Third, facial rejuvenation using the Mint Lift® may be combined with a liposuction (Level of evidence III).

CONCLUSIONS

Here, we propose expert consensus on facial rejuvenation using a novel absorbable PDO monofilament threadlift in Koreans. Of note, this is the only expert consensus prepared by board-certified specialists in plastic surgery in Korea. But more evidence-based efforts should be made to update and to expand the current recommendations.

Analysis of hard tissue facial symmetry after unilateral mandibular reconstruction

Background

This study aimed to determine how successful reconstruction of the mandible can recover the symmetry.

Materials and methods

All patients who underwent surgical treatment for unilateral mandibular reconstruction in 4 years were retrospectively examined. Bilateral differences of gonion (GO) positions were measured in 3 dimensions based on immediate postoperative computed tomography. The data collected was analyzed in 3 ways: First, the comparison of bilateral differences of GO in 3 dimensions. Second, the mean Asymmetry Index in control subjects was used to divide all cases into three groups: “Symmetry,” “Asymmetry,” and “Marked asymmetry.” Third, “maximum normal asymmetry” was calculated, and all cases were categorized as below and above maximum normal asymmetry. The difference between two gonial angles was used to determine the amount of asymmetry.

Results

Forty-seven patients and 47 normal adults were enrolled. The mean bilateral GO difference in the control group was higher than in the study group patients, but it was not statistically significant. The mean Asymmetry Index for the control group was not also significantly higher than the study cases. The study group was “Symmetric” in 78.7% of the cases whereas the control group in 91.4%, 19.1% of the study group and 8.5% of controls were “Asymmetric,” and 2.1% of study cases and 0% of controls were “Markedly Asymmetric.” Maximum normal asymmetry was 82.9% in the study group and 97.8% in the control group. The mean differences between the right and left gonial angles were higher in the study group, but it was not significant (P = 0.1).

Conclusions

Our study’s results showed that bilateral symmetry in mandibular reconstruction patients was satisfactory and similar to the normal individuals.

Tomographic similarity scan with a computed modified absolute mandibular midsagittal plane for precise and objective localization of mandibular asymmetry

The application of 3D imaging is at its cusp in craniofacial diagnosis and treatment planning. However, most applications are limited to simple subjective superimposition-based analysis. As the diagnostic accuracy dictates the precision in operability, we propose a novel method that enables objective clinical decision making for patients with mandibular asymmetry. We analyzed cone-beam computed tomography (CBCT) scans of 34 patients who underwent surgical correction for mandibular asymmetry using a high-throughput computing algorithm. Radiomic segmentation of quantitative features of surface and volume followed by exploration resulted in identification of a computed modified absolute mandibular midsagittal plane (cmAMP). Tomographic similarity scan (ToSS) curves were generated via bilateral equidistant scanning in an antero-posterior direction with cmAMP as the reference. ToSS comprised of a comprehensive similarity index (SI) score curve and a segment-wise volume curve. The SI score was computed using the Sørensen-Dice similarity coefficient ranging from 0 to 1. The volumetric analysis was represented as the non-overlapping volume (NOV) and overlapping volume (OV) for each segment, with two segmentation lines, at the mental foramen anteriorly and the intraoral vertical ramus osteotomy region posteriorly. Statistical analysis showed strong negative correlation between the NOV and SI scores for the anterior, middle, and total mandible (P < 0.001). Additionally, a significant correlation was observed between the change in the SI scores for anterior (P = 0.044) and middle segments (P < 0.001) to the total mandible when comparing the data before and after the surgery. This work demonstrated the potential of incorporating ToSS curves in surgical simulation software to improve precision in the clinical decision-making process.

Ideal Nasal Radix Position in Fluctuating Facial Asymmetry

BACKGROUND

Augmentation rhinoplasty had become increasingly popular among Asians. Failure to recognize nasal deviation before surgery may engender unsatisfactory outcomes because the deviation becomes prominently visible after surgery due to the central position of the nose. Ideal nasal radix positioning has yet to be addressed. The head position affects facial asymmetry judgements; however, its effect on rhinoplasty has never been studied. This study determined the ideal nasal radix position in facial fluctuating asymmetry and investigated the effects of the natural head position (NHP) on nasal deviation perceptions.

METHODS

A survey was conducted to compare different head and nasal radix horizontal positions using images of patients who underwent augmentation rhinoplasty. Images were retouched using editing software to adjust the head and nasal radix positions. The survey was performed using questionnaires involving 3 plastic surgeons and 3 laypersons, who were asked to determine the presence of nasal deviation and select the ideal nasal radix position among the retouched images.

RESULTS

Twenty patients who underwent primary rhinoplasty were included in this study. The recognition of nasal deviation was significantly higher in the NHP than in the compensatory head position. The surgeons and the laypersons considered the midsagittal line the most appropriate position of the nasal radix.

CONCLUSIONS

Facial analysis for augmentation rhinoplasty should be performed with the patient's head in the NHP to prevent nasal deviation masking. The preferred nasal radix position in facial fluctuating asymmetry is the midsagittal line.Level of Evidence: Level V, descriptive study.

Diagnostic analysis of vertical orbital dystopia and canthal tilt for surgical correction

Objectives

We sought to identify a clinically useful method of analyzing orbital dystopia to aid in diagnosis and treatment planning and to quantify vertical discrepancies in eye level and variations in canthal tilt in Koreans.

Patients and Methods

In 76 Korean patients with a mean age of 23.12 years, mean differences in the level of the pupils, lateral canthi, medial canthi, and canthal tilt were measured. The difference in pupil level was calculated from the perpendicular lines drawn from the midpupil area of each eye to the midline of the face to determine the amount of skeletal discrepancy of the eye. Soft tissue discrepancies were determined according to the vertical difference between the lines drawn from the lateral or medial canthus of each eye perpendicular to the midline of the face. The canthal tilt was determined from the inclination of a line connecting the lateral and medial canthi, then classified as class I, II, or III.

Results

Mean differences in pupil level, medial canthi, and lateral canthi were 1.57±1.10 mm, 1.14±1.07 mm, and 2.03±1.64 mm, respectively. The mean degree of canthal tilt were 8.45°±3.53° for the right side and 8.42°±3.81° for the left side. No study participants presented with class III canthal tilt. The mean canthal tilt values for those with class I tilt were 3.21°±1.68° for the right side and 3.18°±1.63° for the left side, while, for those who had class II tilt, the values were 9.60°±3.66° for the right side and 9.54°±2.99° for the left side.

Conclusion

The presented diagnostic method of orbital dystopia can be used to effectively establish a treatment plan that takes into consideration the patient's skeletal and soft-tissue discrepancies.

Effects of Changes in the Frankfort Horizontal Plane Definition on the Three-Dimensional Cephalometric Evaluation of Symmetry

The plane formed by the intersection of bilateral porions (PoR and PoL) and left orbitale (OrL) is conventionally defined as the Frankfort horizontal (FH) plane. We aim to test the influence of the FH plane definition on a 3D cephalometric assessment. We selected 38 adult patients (20 males, 18 females; average age: 22.87 ± 5.17 years) without any gross asymmetry from retrospective records and traced and analyzed their cone-beam computed tomographic images. The findings were categorized into the following four groups: FH1: conventional; FH2: PoR, PoL, right orbitale (OrR); FH3: OrR, OrL, PoL; FH4: OrR, OrL, PoR. The average menton (Me) deviation from the MSP was statistically significant for the FH1 group (0.56 ± 0.27 mm; p < 0.001), compared to the FH3 (1.37 ± 1.23 mm) and FH4 (1.33 ± 1.16 mm) groups. The spatial orientation level (SOL) of the FH plane showed a marked difference (p < 0.05) between the FH2 (0.602° ± 0.503°) and FH4 (0.944° ± 0.778°) groups. The SOL of the MSP was comparatively small (p < 0.001) for FH2 (0.015° ± 0.023°) in comparison to both FH 3 (0.644° ± 0.546°) and FH 4 (0.627° ± 0.516°). Therefore, the FH plane definition can significantly influence the interpretation of cephalometric findings. Future studies should focus on standardization to improve the reliability and reproducibility of 3D cephalometry.

Nasal Floor Asymmetry Is Associated With Nasal Obstruction

PURPOSE

The role of morphologic characteristics of the nasal cavity in nasal obstruction is not yet sufficiently understood. The aim of this study was to determine which morphometric parameters of the nasal cavity severely impair nasal breathing and when.

PATIENTS AND METHODS

In a hospital-based, computed tomography-morphometric cross-sectional study, we evaluated computed tomography coronal scans of patients with known nasal obstruction scheduled to undergo functional nasal surgical procedures (cases) and trauma patients without facial involvement or known nasal obstruction (controls). The primary predictor variable was case versus control. In both groups, we measured and compared the piriform aperture width; nasal floor canting; piriform aperture vertical height, height-width ratio, and total cross-sectional area; height difference between the right and left nasal floors; and nasal septal thickness; as well as age and gender differences. Metric data means, standard deviations, and 95% confidence intervals were calculated and analyzed.

RESULTS

The sample was composed of 60 patients evenly divided between cases and controls. Of these, 30 were men. The average age of the cases and controls was 27.4 ± 7.8 years and 38.5 ± 18.6 years, respectively (P < .001). The differences in piriform aperture width were not statistically significant between cases and controls (23.3 ± 1.9 mm and 23.8 ± 1.7 mm, respectively; P > .2). In contrast, we noted statistically significant differences between cases and controls in nasal floor canting (5.4° ± 4.6° and 1.8° ± 1.5°, respectively; P < .001) and height difference between the right and left nasal floors (1.8 ± 1.2 mm and 1.0 ± 0.7 mm, respectively; P = .002).

CONCLUSIONS

Nasal floor canting of 3° or greater and a height difference between the right and left nasal floors of 1.5 mm or greater may contribute to the etiology of clinically relevant nasal obstruction. A piriform aperture width of 22 mm or less may be considered narrow. Future studies can determine when and how exactly to surgically address a clinically relevant narrow piriform aperture and nasal floor canting.

Skeletal Deformity in Patients With Unilateral Coronal Craniosynostosis: Perceptions of the General Public

Study Design

A two-alternative forced choice design was used to gather perceptual data regarding unicoronal synostosis (UCS).

Objective

Cranial vault remodeling aims at improving the aesthetic appearance of infants with UCS by reshaping the forehead and reducing the potential for psychosocial discrimination. People's perception of craniofacial deformity plays a role in the stigma of deformity. The purpose of this study is to examine the relationship between objective skull deformity in UCS patients and laypersons' perception of skull normality.

Methods

Forty layperson skull raters were recruited from the general public. Skull raters were asked to categorize 45 infant skull images as normal or abnormal. Twenty-one of the images were UCS skulls, and 24 were normal skulls. Skulls were displayed briefly on a computer to simulate a first impression scenario and generate a perceptual response. A χ ² analysis and mixed-effects regression model were used to analyze the response data.

Results

Members of the general public were good at distinguishing between skull groups, χ ² (1) = 281.97, P < .001. In addition, skull raters' responses were predicted by the severity of deformity in the UCS skulls (b = -0.10, z = -2.6, P = .010, CI: -0.18, -0.02). A skull with a deformity value of 2.8 mm (CI: 1.8, 4.1) was equally likely to be rated normal or abnormal.

Conclusions

This is the first study to investigate the relationship between objective skull deformity in UCS and public perception. Laypersons were good at distinguishing the difference between normal and UCS skulls, and their perceptions of normality were predicted by the degree of skull deformity.

Facial Contouring by Using Dermal Fillers and Botulinum Toxin A: A Practical Approach

BACKGROUND

The perception of an attractive face is largely subjective. The purpose of this paper is to provide an insight and a practical approach to facial contouring management with hyaluronic acid (HA) implants and botulinum toxin A.

METHODS

This study is presenting the clinical experience of the authors regarding facial contouring. After a careful medical history, patients underwent an exhaustive aesthetic assessment that includes photographs and videos. Realistic treatment goals were discussed and agreed with the patient. Comprehensive treatment strategies for facial contouring, including HA implants and/or botulinum toxin A injections, were selected according to the patient needs.

RESULTS

Based on the MD codes^®, developed by Mauricio de Maio, these treatment strategies have been adapted to six different basic categories of facial shapes, namely round, square, triangular, inverted triangle, rectangle, oval and oblong faces. The incidence of complications was low and, in all the cases, was mild (edema, erythema and local ecchymosis), of limited duration, and was resolved without sequela.

CONCLUSIONS

The current article presented the personal experiences of the authors on a specific subject, and this fact should be considered when interpreting data from this paper. As other aesthetic treatments, facial contouring should be focused on the patient needs and to select a specific aesthetic approach according to different facial shapes. Finally, it is essential to have a good understanding of the potential associated complications, because it will help the specialist to take the necessary precautions to prevent them, and if they ever arise, to be able to deal with them effectively.

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 .

Cone-beam computed tomography analysis of transverse dental compensation in patients with skeletal Class III malocclusion and facial asymmetry

Objective

The purpose of this study was to analyze the transverse dental compensation in reference to the maxillary and mandibular basal bones using cone-beam computed tomography (CBCT) and evaluate the correlations between transverse dental compensation and skeletal asymmetry variables in patients with skeletal Class III malocclusion and facial asymmetry.

Methods

Thirty patients with skeletal Class I (control group; 15 men, 15 women) and 30 patients with skeletal Class III with menton deviation (asymmetry group; 16 men, 14 women) were included. Skeletal and dental measurements were acquired from reconstructed CBCT images using OnDemand3D 1.0 software. All measurements were compared between groups and between the deviated and nondeviated sides of the asymmetry group. Correlation coefficients for the association between skeletal and dental measurements were calculated.

Results

Differences in the ramus inclination (p < 0.001), maxillary canine and first molar inclinations (p < 0.001), and distances from the canine and first molar cusp tips to the midmaxillary or midmandibular planes (p < 0.01) between the right and left sides were significantly greater in the asymmetry group than in the control group. In the asymmetry group, the ramus inclination difference (p < 0.05) and mandibular canting (p < 0.05) were correlated with the amount of menton deviation. In addition, dental measurements were positively correlated with the amount of menton deviation (p < 0.05).

Conclusions

Transverse dental compensation was correlated with the maxillary and mandibular asymmetry patterns. These results would be helpful in understanding the pattern of transverse dental compensation and planning surgical procedure for patients with skeletal Class III malocclusion and facial asymmetry.

Landmark-based midsagittal plane analysis in patients with facial symmetry and asymmetry based on CBCT analysis tomography

PURPOSE

Reconstruction of the facial midplane is relevant in anthropometry, orthodontics, maxillofacial surgery, and the accurate measurement of symmetry deviation is relevant in many fields of medicine especially when planning surgical treatment. In the literature, three different means of midplane generation have been published; however, there is currently no consensus regarding the approach to use. Morphometric methods are used to determine the true midsagittal plane (MSP), but its use in clinical practice is difficult. A regression plane based on N‑ANS-PNS landmarks reportedly approximates the morphometric MSP. As these points are vulnerable, we investigated which combination of landmarks can be substituted in symmetric and asymmetric faces.

PATIENTS AND METHODS

Thirty symmetric and 30 asymmetric faces were analyzed on cone-beam computed tomography scans. A total of 50 regression planes were generated based on three unpaired landmarks and 35 regression planes were generated based the midpoints of paired landmarks. The Na-ANS-PNS plane was used as reference plane, and the mean angle between it and each generated MSP was calculated. The differences from the reference plane were compared by t‑test between the groups.

RESULTS

In the symmetric group, 86% of angles deviated by <5° using unpaired points, whereby 74% of angles deviated by <5° for paired points. Between the two groups 50% of planes from midline points, and 77% of planes from paired points were significantly different. All planes deviated more in the asymmetric group.

CONCLUSIONS

The N‑ANS-PNS reference plane can be substituted with the following combinations: ANS-G-Ba, ANS-G-S, ANS-S-De, PNS-G-Ba, PNS-S-Ba, PNS-ANS-G, and PNS-N-Ba.

Analyzing Menton Deviation in Posteroanterior Cephalogram in Early Detection of Temporomandibular Disorder

INTRODUCTION

Some clinicians believed that mandibular deviation leads to facial asymmetry and it also had a correlation with temporomandibular disorders (TMDs). Posteroanterior (PA) cephalogram was widely reported as a regular record in treating facial asymmetry and craniofacial anomalies. The objective of this study was to analyze the relationship of menton deviation in PA cephalogram with temporomandibular disorders (TMDs) symptoms.

MATERIALS AND METHODS

TMJ function was initially screened based on TMD-DI questionnaire. PA cephalogram of volunteer subjects with TMDs (n = 37) and without TMDs (n = 33) with mean age of 21.61 ± 2.08 years was taken. The menton deviation was measured by the distance (mm) from menton point to midsagittal reference (MSR) horizontally, using software digitized measurement, and categorized as asymmetric if the value is greater than 3 mm. The prevalence and difference of menton deviation in both groups were evaluated by unpaired t-test.

RESULT

The prevalence of symmetry group showed that 65.9% had no TMDs with mean of 1,815 ± 0,71 mm; in contrast, the prevalence of asymmetry group showed that 95.5% reported TMDs with mean of 3,159 ± 1,053 mm. There was a significant difference of menton deviation to TMDs (p = 0.000) in subjects with and without TMDs.

CONCLUSION

There was a significant relationship of menton deviation in PA cephalogram with TMDs based on TMD-DI index.