Evaluation of the relationship between malar projection and lower facial convexity in terms of perceived attractiveness in 3-dimensional reconstructed images

Assessment of Malar Prominence in Adolescents: Evaluating the Diagnostic Accuracy of a New Angle for Vector Profile Classification

INTRODUCTION

The prominence of the malar region plays a crucial role in facial aesthetics; however, standardized diagnostic parameters for assessing midfacial deficiencies remain limited. This study introduced and evaluated a novel cephalometric parameter, the double W-key ridge (DWK) angle (formed between the double W plane and the key ridge point), in comparison with the established sella-nasion-orbitale (SNO) angle for assessing malar prominence. This study aimed to present a novel perspective for evaluating malar prominence, referred to as the DWK angle. The objectives of this study were to compare the mean SNO and DWK angles between positive and negative vector profiles, assess their correlation, evaluate their diagnostic accuracy using receiver operating characteristic (ROC) analysis, and examine the influence of sex on these parameters.

MATERIALS AND METHODS

This retrospective study analyzed the lateral cephalograms and profile photographs of 60 young adolescents (aged 11-14 years) from the Department of Orthodontics, Yogita Dental College. Based on clinical photographs, records were classified into positive and negative vector profile groups (n=30 each). The same observer obtained cephalometric measurements of the SNO and DWK angles. Reliability testing was conducted using the intraclass correlation coefficient. Statistical analyses, including Mann-Whitney U tests, Spearman's rank correlation, mixed-model analysis, and ROC curve analysis using the area under the curve (AUC), were performed to assess the relationship, diagnostic accuracy, and potential sex differences in these measurements.

RESULTS

Mean SNO and DWK angles were significantly higher in the positive vector group (SNO, 53.97°; DWK, 104.2°) than in the negative vector group (SNO, 44.1°; DWK, 94.6°) (p<0.001). A strong positive correlation (r=0.74, p=0.001) was observed between these two angles. ROC analysis demonstrated high diagnostic accuracy for both angles (AUC: 0.947 for SNO and 0.961 for DWK), with a sensitivity and specificity of 90%. No significant sex-based differences were found in either of the vector groups.

CONCLUSION

DWK angle is a stable and reliable cephalometric parameter for differentiating between adolescents' positive and negative vector profiles. The strong correlation and high diagnostic accuracy suggest that both SNO and DWK angles can effectively be utilized in orthodontics and maxillofacial planning to assess malar prominence.

Smartphone-generated 3D facial images: reliable for routine assessment of the oronasal region of patients with cleft or mere convenience? A validation study

OBJECTIVES

To evaluate the validity and reliability of smartphone-generated three-dimensional (3D) facial images for routine evaluation of the oronasal region of patients with cleft by comparing their accuracy to that of direct anthropometry (DA) and 3dMD.

MATERIALS AND METHODS

Eighteen soft-tissue facial landmarks were manually labelled on each of the 17 (9 males and 8 females; mean age 23.3 ± 5.4 years) cleft lip and palate (CLP) patients' faces. Two surface imaging systems, 3dMDface and Bellus3D FaceApp, were used to perform two imaging operations on each labelled face. Subsequently, 32 inter-landmark facial measurements were directly measured on the labelled faces and digitally measured on the 3D facial images. Statistical comparisons were made between smartphone-generated 3D facial images (SGI), DA, and 3dMD measurements.

RESULTS

The SGI measurements were slightly higher than those from DA and 3dMD, but the mean differences between inter-landmark measurements were not statistically significant across all three methods. In terms of clinical acceptability, 16% and 59% of measures showed differences of ≤ 3 mm or ≤ 5º, with good agreement between DA and SGI and 3dMD and SGI, respectively. A small systematic bias of ± 0.2 mm was observed generally among the three methods. Additionally, the mean absolute difference between the DA and SGI methods was the highest for linear measurements (1.31 ± 0.34 mm) and angular measurements (4.11 ± 0.76º).

CONCLUSIONS

SGI displayed fair trueness compared to DA and 3dMD. It exhibited high accuracy in the orolabial area and specific central and flat areas within the oronasal region. Notwithstanding this, it has limited clinical applicability for assessing the entire oronasal region of patients with CLP. From a clinical application perspective, SGI should accurately encompass the entire oronasal region for optimal clinical use.

CLINICAL RELEVANCE

SGI can be considered for macroscopic oronasal analysis or for patient education where accuracy within 3 mm and 5º may not be critical.

Truth Lies in the Depths: Novel Insights into Facial Aesthetic Measurements from a U.S. Survey Panel

BACKGROUND

Aesthetic facial bone surgery and facial implantology expand the boundaries of conventional facial surgery that focus on facial soft tissue. This study aimed to reveal novel aesthetic facial measurements to provide tailored treatment concepts and advance patient care.

METHODS

A total of n=101 study participants (46 females and 55 males) were presented with 120 patient portraits (frontal images in natural head posture; 60 females and 60 males) and asked to assess the facial attractiveness (scale 0-10; "How attractive do you find the person in the image?") and the model capability score (MCS; scale 0-10; "How likely do you think the person in the image could pursue a modelling career?"). For each frontal photograph, defined facial measurements and ratios were taken to analyse their relationship with the perception of facial attractiveness and MCS.

RESULTS

The overall attractiveness rating was 4.3 ± 1.1, while the mean MCS was 3.4 ± 1.1. In young males, there was a significant correlation between attractiveness and the zygoma-mandible angle (ZMA)2 (r= - 0.553; p= 0.011). In young and middle-aged females, MCS was significantly correlated with facial width (FW)1-FW2 ratio (r= 0.475; p= 0.034). For all male individuals, a ZMA1 value of 171.79 degrees (Y= 0.313; p= 0.024) was the most robust cut-off to determine facial attractiveness. The majority of human evaluators (n=62; 51.7%) considered facial implants a potential treatment to improve the patient's facial attractiveness.

CONCLUSION

This study introduced novel metrics of facial attractiveness, focusing on the facial skeleton. Our findings emphasized the significance of zygomatic measurements and mandibular projections for facial aesthetics, with FI representing a promising surgical approach to optimize facial aesthetics.

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 .

Influence of facial width on the perception of lip protrusion and its differences between profile and 3-dimensional video clip

INTRODUCTION

This study evaluated the influence of facial width on the perception of lip protrusion and investigated the concordance between 2-dimensional (2D) profile images and 3-dimensional (3D) video clips in assessing lip protrusion.

METHODS

An Asian female standard head model was created using 3D modeling software. Eight head models were constructed by modifying the standard head model in terms of facial width (broad, neutral, and slim) and lip protrusion (retrusive, straight, and protrusive). Overall, 97 Asian raters rated the lip protrusion from the 2D profiles and 3D rotation video clips of the 9 models.

RESULTS

No significant differences were found in the perception of lip protrusion in terms of sex, age, or occupation. Compared with the 2D profiles, the 3D video clips were rated as more protrusive in 8 of the 9 head models, with the retrusive broad, retrusive neutral, straight broad, and straight slim faces showing statistical significance (P <0.01). The rating is significantly higher in slim faces than in broad faces across the 3 groups of 2D profiles (P <0.01). For 3D video clips, the rating was higher in slim faces than in broad faces in all 3 groups, whereas differences were significant in the straight and protrusive groups only (P <0.01).

CONCLUSIONS

In this study, 3D video clips were more sensitive to the perception of lip protrusion than were 2D profiles to some extent. The lips were rated relatively more protrusive in a slim face than in a broad face. Therefore, the relationship between facial width and lip protrusion should be considered in orthodontic treatment goals and treatment plans.

Improvement in facial aesthetics of orthognathic patients after surgery-first approach

Facial appearance significantly affects psychosocial wellbeing, and an improvement in facial aesthetics is considered an essential outcome of orthognathic treatment. The surgery-first approach (SFA) has emerged as a promising alternative to the conventional orthodontics-first approach (OFA) due to its potential advantages in reducing treatment duration and cost, delivering early aesthetic improvement, and increasing patient satisfaction. However, its impact on final facial aesthetics and how it compares with the OFA has, to our knowledge, not yet been investigated. This retrospective study aimed to compare the improvement in facial aesthetics after orthognathic surgery in an SFA and an OFA group. Preoperative and postoperative 3-dimensional stereophotogrammetry facial images of 40 patients were evaluated by five professional assessors using the Global Aesthetic Improvement Scale (GAIS). Similar aesthetic improvement outcomes were found in both the SFA and OFA groups. The GAIS score significantly correlated with the following facial variables: upper lip projection, chin prominence, facial proportions, paranasal hollowing, lip competence, mandibular projection, and facial profile. No significant correlation was found between a change in aesthetic score and the surgical variables. There was a positive association between overall GAIS score and the gender and experience level of the individual assessors. This study suggests that aesthetic facial improvement achieved with the SFA is satisfactory and comparable to that of the OFA.

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.

The reliability of analytical reference lines for determining esthetically pleasing lip position: An assessment of consistency, sensitivity, and specificity

INTRODUCTION

This study aimed to identify a simple yet reliable soft-tissue parameter for the clinical determination of esthetic lip position by investigating the most consistent reference lines and assessing their sensitivity and specificity.

METHODS

A total of 5745 records from Chinese patients aged >18 years were screened. In part I of the study, lateral view photographs of 96 subjects (33 males, 63 females) with esthetic facial profiles were selected. The profile esthetics of each photograph was first scored by 52 dental students, followed by 97 laypeople on a 5-point attractiveness scale. For the top 25% of photographs with the highest score for each sex (8 males, 16 females), the consistency of 6 commonly used reference lines were assessed to determine the esthetic lip position. In part II of the study, lip positions relative to Steiner's (S) and Ricketts' (E) lines in the profile photographs of 86 patients (43 males, 43 females) deemed to have an esthetically unpleasing profile were compared with those in 86 Chinese movie star idols (43 males, 43 females).

RESULTS

In part I of the study, the S, E, and Burstone's (B) lines exhibited the lowest standard deviations for the upper and lower lips. B line was excluded from further analysis because of its higher mean absolute values, and S and E lines were used for the subjective assessment in part II of the study. In part II, the S line showed a sensitivity of 86.0% and 86.0% and a specificity of 81.4% and 83.7% for males and females, respectively. In contrast, the E line presented a sensitivity of 88.4% and 93.0% and a specificity of 79.1% and 74.4% for males and females, respectively.

CONCLUSIONS

S, E, and B lines were the most consistent soft-tissue parameters among both sexes; however, because of the smaller absolute values, the S line would be more convenient among the 3 for a quick clinical assessment of lip position. Moreover, the performance of both S and E lines was similar among both sexes, which supports using these lines in assessing the esthetic lip position.

Skeletal Contouring Techniques in the Ethnic Patient

The zygomaticomaxillary complex and mandible play a significant role in facial beauty. The projection of these bones drapes and conforms the overlying soft tissues, resulting in the light reflections and shadows that define a face. The size, contour, and projection of these bones of beauty are sexually dimorphic and ethnically defined. Excessive projection of these bones in any dimension can lead to undesirable esthetic appearance. Reduction malarplasty and mandibuloplasty are effective techniques that can be used to reshape the facial skeleton to a more desirable shape.

Reduction malarplasty using a simulated surgical guide for asymmetric/prominent zygoma

Background

The present study introduces a reduction malarplasty using a three-dimensional (3D)-printed surgical guide and evaluates the guide’s technical applicability.

Methods

Twenty malarplasties were performed for 12 subjects with zygomatic asymmetry/prominency using the current method. 3D reconstruction of the craniomaxillofacial region and fine dental occlusion was made with image data from computed tomograpy and dental scanning. A computer-assisted surgical simulation was performed for reduction malarplasty and a surgical guide was designed for later 3D printing. The manufactured surgical guide was introduced to the operation field to guide the surgery; its surgical accuracy was confirmed by comparing five corresponding points from preoperative simulation and postoperative data.

Results

We successfully performed the reduction malarplasty with the surgical guide. The accuracy level of surgery fell to 0.93 mm of total median difference for the corresponding zygoma points of preoperative simulations and postoperative zygoma. The anterior and upper points showed less error level (0.59 and 0.73 mm difference, respectively) than did other points.

Conclusions

We developed a computer-assisted surgical technique using a surgical guide for asymmetrical/prominent zygoma which proved to be simple, practical, and accurate; it is expected to help surgeons perform reduction malarplasty with ease and accuracy.