Quantitative analysis of 3-dimensional facial soft tissue photographic images: technical methods and clinical application

The Treatment of Alar Base Depression in Rhinoplasty with Diced Autologous Cartilage or Mass Cartilage: A Systematic Review

BACKGROUND

Alar base is the basal part where the two sides of the nose and the upper lip are connected. Alar base depression affects the overall facial contour by making the nasolabial folds deepen, the nasolabial angle smaller, the center of the face flat, etc. Despite the rapid development of rhinoplasty, controversy still exists regarding the treatment of alar base depression. This systematic review aims to evaluate the efficacy and safety of two prevalent techniques-diced autologous cartilage and mass cartilage-for addressing alar base depression.

METHODS

A systematic review was conducted by searching the literature published in PubMed, Embase and Web of Science, Cochrane from January 2000 to April 2023 with the key words 'alar base depression or depressed alar base' and 'alar base augmentation,' and 2 investigators independently screened the retrieved literature according to inclusion and exclusion criteria.

RESULTS

A total of 269 articles were obtained through database search. After removing duplicates, reading titles and abstracts, and finally reviewing the full text, 6 articles were included in the final study, including 165 patients.

CONCLUSIONS

The results demonstrate that both diced autologous cartilage and mass cartilage techniques exhibit favorable outcomes in correcting alar base depression. Diced autologous cartilage offers better malleability, lighter border contours, and a more natural appearance. On the other hand, diced autologous cartilage seems to offer superior long-term effects, while mass cartilage presents certain surgical procedural advantages. Also, compared to diced cartilage, mass cartilage may have a lower rate of long-term resorption and a lower risk of displacement. This review emphasizes the need for personalized treatment selection based on individual patient characteristics.

LEVEL OF EVIDENCE III

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 .

Application of Auricular Cartilage-Skin Graft in the Reconstruction of Unilateral Cleft Lip Nasal Deformity

BACKGROUND

Autologous cartilage grafts are increasingly used in the treatment of cleft lip nasal deformity, but nasal alar retraction caused by lining defects often occurs after surgery. We designed a new graft to treat unilateral cleft lip nasal deformity while avoiding nasal alar retraction.

METHODS

Nineteen patients in our hospital underwent unilateral cleft lip nasal deformity repair surgery with an auricular cartilage-skin graft. The effect of surgery was evaluated in four aspects: satisfaction with postoperative appearance, nasal aesthetic subunit indices, position of the nasal alar rim and three-dimensional spatial difference.

RESULTS

Overall satisfaction with each index was above 90%. The nasal tip angle and nasolabial angle of patients were significantly smaller after surgery than before surgery (P < 0.01). The height of the nostril on the affected side and the length of the nasal columella were greater after surgery than before surgery (P < 0.01). The spatial differences in soft tissue between the unaffected side and the affected side after surgery were significantly smaller than before surgery (P < 0.01). According to the follow-up results of 1-2 years, there were no significant retraction of the nasal alar rim (P > 0.05) and no obvious auricular deformity. All patients had a noticeable improvement in their nasal appearance.

CONCLUSION

The auricular cartilage-skin graft, which can not only improve the appearance of the nose but also avoid nasal alar retraction, is an ideal graft to cure unilateral cleft lip nasal deformity.

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 .

Association between adiposity and facial aging: results from a Mendelian randomization study

BACKGROUND

Skin, as a sociologically meaningful interface, has psychological implications different from other organs, particularly in the context of the global population aging. Growing evidence suggests that facial aging is associated with an increased risk of adiposity. Existing research, however, were observational, and while they may find some correlations, it is difficult to simply disentangle non-causal or reverse-causal links because these associations may be confounded or fail to accurately reflect true causative linkages.

OBJECTIVES

We conducted a 2-sample Mendelian randomization (MR) study to examine the potential effect of facial aging on the risk of broad obesity and its three major adiposity indicators, including body mass index (BMI), body fat percentage (BF%) and waist circumference (WC).

METHODS

Genetic instruments from IEU OpenGWAS project, one of the largest available genome-wide association studies (GWAS) for facial aging (423,999 samples) were used to investigate the relation to broad obesity (32,858 cases, 65,839 controls). Using the inverse-variance weighted (IVW) technique, single nucleotide polymorphisms (SNPs) associated with adiposity indicators (BMI (461,460 samples), BF% (454,633 samples), and WC (462,166 samples)) were investigated in relationship to facial aging. Further sensitivity analyses were performed, including Mendelian randomization-Egger (MR-Egger), weighted median estimates, and leave-one-out analysis, to evaluate the consistency of the results and related potential issues in MR studies.

RESULTS

We identified strong and significant correlations between adiposity and facial aging in the 17 broad obesity-associated SNPs (IVW estimate of odds ratio OR = 1.020, 95% CI 1.010-1.029, P = 7.303e - 05), 458 BMI-associated SNPs (IVW estimate of odds ratio OR = 1.047, 95% CI 1.0357-1.058, P = 1.154e - 16),for the 395 BF%-associated SNPs (OR = 1.056, 95%CI 1.040-1.072,P = 7.617e - 12), or for the 374 WC-associated SNPs (OR = 1.072, 95% CI 1057-1.087,P = 1.229e - 23). A range of complementary methodologies have been employed to evaluate horizontal pleiotropy and related potential caveats occurring in MR research.

CONCLUSIONS

Using Mendelian randomization as an alternative approach to investigate causality, we found a causal relationship between adiposity and facial aging, which was statistically strong and significant.

Developing a three-dimensional statistical shape model of normal dentition using an automated algorithm and normal samples

OBJECTIVES

The statistical shape model (SSM) is a model of geometric properties of a set of shapes based on statistical shape analysis. The SSM develops an average model of several objects using an automated algorithm that excludes the operator's subjectivity. The aim of this study was to develop a three-dimensional (3D) SSM of normal dentition to provide virtual templates for efficient treatment.

MATERIALS AND METHODS

Dental casts were obtained from participants with normal dentition. After acquiring the 3D models, the SSMs of the individual teeth and whole dental arch were generated by an iterative closest point (ICP)-based rigid registration and point correspondences, respectively. Then, the individual tooth SSM was aligned to the whole dental arch SSM using ICP-based registration to generate an average model of normal dentition.

RESULTS

The generated 3D SSM showed specific morphological features of normal dentition similar to those previously reported. Moreover, on measuring the arch dimensions, all values in this study were similar to those previously reported using normal dentition.

CONCLUSIONS

The 3D SSM of normal dentition may increase the diagnostic efficiency of orthodontic treatments by providing a visual objective. It can be also used as a 3D template in various fields of dentistry.

CLINICAL RELEVANCE

Our SSM of normal dentition provides both quantitative and qualitative information on the 3D morphology of teeth and dental arches, which may provide valuable information on 3D virtual-setup, bracket fabrication, and aligner treatment.

Assessing the Influence of Chin Asymmetry on Perceived Facial Esthetics With 3-Dimensional Images

PURPOSE

We used 3-dimensinonal (3D) images to assess the influence of chin asymmetry on perceived facial esthetics, investigate the cognitive boundaries of chin asymmetry among orthodontists, general dentists, and laypersons, and provide quantitative reference for clinical treatment.

MATERIALS AND METHODS

A 3D facial image was obtained using the 3dMD imaging system (3dMD, Atlanta, GA). The chin was altered in 2-mm increments from 0 to 12 mm and to the left and right using the software program. These images were rated by 66 orthodontists, 89 general dentists, and 66 laypersons as 1) chin symmetry; 2) slight chin asymmetry but acceptable; and 3) serious asymmetry and treatment needed. Multivariate mixed linear regression and multivariate mixed logistic regression analyses were used for statistical data analysis. Descriptive and bivariate statistics were calculated, and statistical significance was considered present at P = .05.

RESULTS

The observers progressively increased the grade ratings and the desire for surgery for greater asymmetries (P < .001). Orthodontists and general dentists could perceive a chin deviation of 4 mm to the right and 2 mm to the left, with 8-mm deviation considered to require treatment. Laypersons had a clear perception of a 4-mm chin deviation, with 8 mm to the right and 10 mm to the left considered to require treatment. The right chin deflection was more easily perceived than was the left (P < .05).

CONCLUSIONS

Chin asymmetry has a great influence on facial esthetics. We found a statistically significant difference between clinicians (orthodontists and general dentists) and laypersons in the cognition of chin asymmetry and the recommendations for treatment.

Perspective Morphometric Criteria for Facial Beauty and Proportion Assessment

Common sense usually considers the assessment of female human attractiveness to be subjective. Nevertheless, in the past decades, several studies and experiments showed that an objective component in beauty assessment exists and can be strictly related, even if it does not match, with proportions of features. Proportions can be studied through analysis of the face, which relies on landmarks, i.e., specific points on the facial surface, which are shared by everyone, and measurements between them. In this work, several measures have been gathered from studies in the literature considering datasets of beautiful women to build a set of measures that can be defined as suggestive of female attractiveness. The resulting set consists of 29 measures applied to a public dataset, the Bosphorus database, whose faces have been both analyzed by the developed methodology based on the expanded set of measures and judged by human observers. Results show that the set of chosen measures is significant in terms of attractiveness evaluation, confirming the key role of proportions in beauty assessment; furthermore, the sorting of identified measures has been performed to identify the most significant canons involved in the evaluation.

Three-Dimensional Territory and Depth of the Corrugator Supercilii: Application to Botulinum Neurotoxin Injection

This study aimed to determine the three-dimensional (3D) territory and depth of the corrugator supercilii muscle (CSM) using a 3D structured-light scanner. Thirty-two hemifaces from Korean and Thai embalmed cadavers were used in this study, and 35 healthy young Korean subjects also participated. A 3D analysis of the CSM territory and depth was performed using a structured-light 3D scanner. The most frequently observed locations of the CSM identified in the cadaver were confirmed in healthy young subjects using a real-time two-dimensional B-mode ultrasonography system. The CSM was present in all of the cadavers and healthy young subjects at the intersection point between the vertical line passing through the medial canthus and the horizontal line passing through the glabella (Point #6). The CSM was located on the medial side of the lateral limbus in most cases. The most-medial and most-lateral origin points were at depths of 5.7 ± 1.4 mm (mean ± SD) and 6.6 ± 1.4 mm, respectively; the corresponding depths of the insertion points were 5.4 ± 1.4 mm and 5.6 ± 2.1 mm, respectively. The origin and insertion points of the CSM were at similar depths. The injection depth should be around 4 mm for botulinum neurotoxin (BoNT) injections into the CSM. Point #6 could be regarded as an effective target point for managing the glabellar frown line and preventing palpebral ptosis when injecting BoNT into the CSM. Clin. Anat., 33:795-803, 2020. © 2019 Wiley Periodicals, Inc.

The Esthetic Difference of Chinese Beauty Evaluated by Two Different Human Races Based on Three-Dimensional Average Face Analysis

Supplemental Digital Content is available in the text

Purpose:

The aim of this study was to establish a new method of facial soft tissue analysis based on 3dMDface system and to find the different esthetic preferences of Chinese beauties from the Chinese and Indian evaluators perspective.

Methods:

Three-dimensional facial images of 242 females and 168 males were evaluated and ranked by 8 Chinese and nine Indians using a 10-point visual analog scale (VAS). Total 120 subjects in 2 panels (from Chinese perspective and Indian perspective) including 30 male and 30 female faces with top 30 scores were analyzed with the “average face” method respectively. Then 17 linear measurements, 13 curve measurements and 14 ratios of 4 average faces were calculated and compared with the divine proportion.

Results:

Distinct differences were founded based on the average face analysis. Similar total facial types were preferred by both Chinese and Indian evaluators, while Indian evaluators preferred a wider male face with a protrusive lower lip. Delicate noses with lower nose ridge but protrusive lower lips in females were more acceptable by Indian evaluators. The differences of linear measurements were limited in 2.0 mm except the facial width, lower facial width, upper facial height and forehead height while curve measurements differ distinctly as the table shows. No ratios equal to the divine proportion were founded.

Conclusion:

The 3D Average face based on stereophotogrammetry is a feasible method to analyze the facial characters and discrepancy of esthetic preferences. Chinese and Indian evaluators have some certain differences when judging beauties. Attractive faces have some certain ratios but not the divine proportion.

Volumetric Analysis of Fat Injection by Computerized Tomography in Orthognathic Surgery: Preliminary Report on a Novel Volumetric Analysis Process for the Quantification of Aesthetic Results

BACKGROUND

Integrated approaches to orthognathic surgery should include accurate volumetric evaluation of the skull and soft tissues. In patients with dentofacial deformities, the most frequent aesthetic deficits are attributable to an underdevelopment of hard and soft tissues. Traditional osteotomic procedures often fail to guarantee a stability of soft tissues over time. For this reason, in selecting a surgical strategy, the surgeon should consider not only traditional osteotomies, but also soft-tissue improving procedures, such as lipofilling. Preoperative surgical planning systems, such as the Virtual surgical planning (VSP) protocol, are based mainly on skeletal movement prediction. Quantitative estimation of soft-tissue modifications is not part of common clinical practice. Most commonly, the evaluation of soft-tissue modifications after orthognathic procedures is instead performed by clinical qualitative means.The purpose of this study was to describe a novel computed tomography (CT)-based volumetric analysis process for the quantification of injected autologous adipose tissue in patients who have undergone simultaneous orthognathic and lipofilling procedures.

METHODS

This was a retrospective review of consecutive patients who underwent combined orthognathic surgery and lipofilling from June 2016 to May 2017 for malocclusion with functional and aesthetic impairments. Preoperative planning included clinical evaluation and virtual osteotomy planning according to the VSP protocol. The volume of fat to be injected was estimated clinically by comparing virtual renderings with preoperative clinical photographs. The surgical technique involved Le Fort I and sagittal split mandibular osteotomies, combined with autologous fat injection in the malar and perioral regions. Postoperative evaluation was performed with a novel imaging process based on CT image segmentation to quantify the exact volume of injected fat. Skeletal stability was also evaluated at 3 months.

RESULTS

Sixteen patients were enrolled in the study, all females, with a mean age of 24.5 years (range, 18-36 years). The mean difference between the fat tissue injected and that quantified postoperatively was 6.01 cm. All patients had clinically satisfactory facial convexity, with complete restoration of the cheekbone contour, at 3 months.

CONCLUSION

This study introduces a novel CT-image based technique to quantitatively assess the contribution of injected fat to the postoperative soft-tissue volume increase after combined orthognathic surgery with autologous lipofilling. In the future, this CT-based volumetric analysis technique could be the gold standard for evaluating facial lipofilling outcomes, and for assessing clinical aesthetic outcomes based on the injected volume of fat.

Three-dimensional soft tissue analysis of the face following micro-implant-supported maxillary skeletal expansion

Background

Skeletal maxillary expander (MSE) is one of the more recent expander designs being utilized for skeletal expansion by splitting the midpalatal sutures applying forces through palatal micro-implants. Its effects on the soft tissue remain a question asked by both patients and clinicians. The aim of this study was to analyze and quantify soft tissue facial changes induced by MSE.

Methods

3D facial images (3dMD) were used to capture face scans of 25 patients generating 3D soft tissue meshes before expansion (T0), right after expansion (T1), and 1 year in retention (T2). MATLAB was then used, utilizing non-rigid iterative closest point algorithm, to align all samples in vertex correspondence and generate averages. Surface mapping of each average, along with its variance, allows for quantification of changes between the three pools of samples in 3D space.

Results

The generated 3D p-maps between T0 and T1 demonstrate that statistically significant changes (p < 0.05 and p < 0.01) are localized in the circummaxillary area (paranasal, lips, and both cheeks). Vector map shows a mean displacement of 1.5 mm in the paranasal area. The right cheek showing a mean displacement magnitude of 2.5 mm while the left cheek has a mean of 2.9 mm. Direction of vectors are latero-anterior with more dominant anterior direction.

Conclusions

There are significant changes in paranasal, upper lip, and at both cheeks following expansion using MSE with greater magnitude at the cheeks area. Those changes do not relapse after 1 year (p < 0.05).

Esthetic evaluation of facial cheek volume: A study using 3D stereophotogrammetry

OBJECTIVES

To investigate the influence of cheek volume on facial esthetics judged by orthodontists and non-specialists.

MATERIALS AND METHODS

A 25-year-old female's natural and smiling face was captured by 3D stereophotogrammetry. Cheek volume of the 3D image was altered to different degrees three-dimensionally. For the natural and smiling face, seven groups of facial images were created: decreased grade I/II/III, increased grade I/II/III, and the original one. Thirty orthodontists and 30 nonspecialists were invited to perform esthetic evaluation of the original and transformed images using a questionnaire. Data were calculated with one-way analysis of variance (least significant difference test) and independent samples t test.

RESULTS

Compared to nonspecialists, orthodontists gave lower esthetic scores to the decreased grade III facial images (maximum deformation degree: 7.500 mm and 7.327 mm in natural and smiling face-oriented image groups, respectively). The decreased grade III facial images also received the highest age ranks. However, the increased grade III facial images received the lowest scores and highest age ranks from nonspecialists (maximum deformation degree: 6.994 mm and 5.300 mm in natural and smiling face-oriented image groups, respectively) ( P < .01).

CONCLUSIONS

Orthodontists and nonspecialists showed different esthetic evaluation of varied cheek volume. The influence of cheek volume in orthodontic diagnostic analysis needs further consideration.

Comparison of two- and three-dimensional assessment methods of nasolabial appearance in cleft lip and palate patients: Do the assessment methods measure the same outcome?

OBJECTIVE

For the assessment of the nasolabial appearance in cleft patients, a widely accepted, reliable scoring system is not available. In this study four different methods of assessment are compared, including 2D and 3D asymmetry and aesthetic assessments.

METHODS

The data and ratings from an earlier study using the Asher-McDade aesthetic index on 3D photographs and the outcomes of 3D facial distance mapping were compared to a 2D aesthetic assessment, the Cleft Aesthetic Rating Scale, and to SymNose, a computerized 2D asymmetry assessment technique. The reliability and correlation between the four assessment techniques were tested using a sample of 79 patients.

RESULTS

The 3D asymmetry assessment had the highest reliability and could be performed by just one observer (Intraclass correlation coefficient (ICC): 0.99). The 2D asymmetry assessment of the nose was highly reliable when performed by just one observer (ICC: 0.89). However, for the 2D asymmetry assessment of the lip more observers were needed. For the 2D aesthetic assessments 3 observers were needed. The 3D aesthetic assessment had the lowest single-observer reliability (ICC: 0.38-0.56) of all four techniques. The agreement between the different assessment methods is poor to very poor. The highest correlation (R: 0.48) was found between 2D and 3D aesthetic assessments. Remarkably, the lowest correlations were found between 2D and 3D asymmetry assessments (0.08-0.17).

CONCLUSION

Different assessment methods are not in agreement and seem to measure different nasolabial aspects. More research is needed to establish exactly what each assessment technique measures and which measurements or outcomes are relevant for the patients.

Three-Dimensional Anthropometric Database of Attractive Caucasian Women: Standards and Comparisons

The aim of this paper is to develop a database to determine a new biomorphometric standard of attractiveness. Sampling was carried out using noninvasive three-dimensional relief methods to measure the soft tissues of the face. These anthropometric measurements were analyzed to verify the existence of any canons with respect to shape, size, and measurement proportions which proved to be significant with regard to the aesthetics of the face. Finally, the anthropometric parameters obtained were compared with findings described in the international literature.

The study sample was made up competitors in the Miss Italy 2010 and 2009 beauty contest. The three-dimensional (3D) scanning of soft tissue surfaces allowed 3D digital models of the faces and the spatial 3D coordinates of 25 anthropometric landmarks to be obtained and used to calculate linear and angular measurements. A paired Student t test for the analysis of the means allowed 3 key questions in the study of biomorphometric parameters of the face to be addressed through comparison with the data available in the literature.

The question of statistical evidence for the samples analyzed being members of the populations samples reported in literature was also addressed.

The critical analysis of the data helped to identify the anthropometric measurements of the upper, middle, and lower thirds of the face, variations in which have a major influence on the attractiveness of the face. These changes involve facial width, height, and depth. Changes in measurements of length, angles, and proportions found in the sample considered were also analyzed.

Facial asymmetry assessment in adults using three-dimensional surface imaging

Background

The use of three-dimensional (3D) surface imaging is becoming more popular and accepted in the fields of Medicine and Dentistry. The present study aims to develop a technique to automatically localise and quantify soft-tissue asymmetry in adults using 3D facial scans. This may be applied as a diagnostic tool to monitor growth and dynamic changes and to evaluate treatment outcomes.

Methods

3D facial surface data were captured from 55 adults comprising 28 symmetrical faces and 27 asymmetrical faces using a 3dMDface system. A landmark-independent method, which compared the original and the mirrored 3D facial data, was developed to quantify the asymmetry. A Weibull distribution-based probabilistic model was generated from the root-mean-square (RMS) error data for the symmetrical group to designate a level of asymmetry which represented a normal range.

Results

Statistically significant (p < 0.0001) differences in the RMS error values were found when comparing symmetrical with asymmetrical groups and a similarly significant difference was identified between the lower and the upper face of the asymmetrical group.

Conclusions

The proposed 3D imaging-based method of identifying and quantifying facial soft-tissue asymmetry was fast and effective. The Weibull distribution-based comparison of a person’s asymmetry with respect to a large sample of symmetrical faces may also be used to evaluate growth, soft-tissue compensations and surgical outcomes.