Accuracy and precision of a 3D anthropometric facial analysis with and without landmark labeling before image acquisition

Three-Dimensional Anthropometric Facial Analysis and Fitting Discrepancies Between Stereophotogrammetry and CT

BACKGROUND

The reliability and repeatability of stereophotogrammetry and CT in 3-dimensional anthropometric facial analysis were investigated in this study, which also explored the clinical application of supine CT.

METHOD

In this study, 3D CT and 3dMD stereophotogrammetry were used on 20 healthy volunteers. The fitting distance between stereophotogrammetry and CT scans at landmark points was measured, along with facial feature measurements (Al-Al) face width (Go-Go, Zy-Zy, Ex-Ex), and hemi-face height (Sn-Gn). The intraclass correlation coefficient (ICC) was employed to assess interrater agreement and to verify the reliability of the measurement methods. Paired t -analysis was utilized for analyzing intramethod displacement.

RESULTS

The alare, nasion, and pronasale points were found to be minimally influenced by different positions and are more recommended as landmark points for registration. CT demonstrated good interrater reliability on all indicators. In stereophotogrammetry, measurements for Go-Go and Zy-Zy displayed an interclass correlation coefficient (ICC) of less than 0.75. Significant differences between the 2 methods were observed for En-En, Ex-Ex, and Go-Go ( P < 0.05). Specifically, CT analysis for Go-Go showed a measurement 2.34 mm larger than that obtained with the 3dMD method.

CONCLUSION

Both CT and stereophotogrammetry were found to be reliable methods for evaluating facial soft tissue. It is speculated that Go-Go measurement is primarily influenced by factors such as different positions, facial expressions, and gravity. These variables should be carefully considered during the evaluation of the mandibular angle region.

Accuracy of Smartphone-Based Three-Dimensional Facial Scanning System: A Systematic Review

BACKGROUND

Recently, the integration of 3D face scanning into smartphones has raised vast interest in plastic surgery. With the release of smartphones featuring 3D face scanning technology, users now can capture detailed 3D models of their faces using their smartphones. However, trueness and precision of this system is less well established.

METHODS

PubMed, Cochrane Library, Embase, ScienceDirect, Scopus, and Web of Science databases were searched for studies evaluating 3D scanning of smartphone devices and conventional 3D imaging systems from January 1, 2017, to June 1, 2023. A qualitative systematic review was conducted by two review authors after independently selecting studies, extracting data, and assessing the risk of bias of included studies.

RESULTS

A total of 11 studies were included, all focusing on the accuracy of smartphone 3D facial scanning. The results show that although smartphones perform poorly on deep and irregular surfaces, they are accurate enough for clinical applications and have the advantage of being economical and portable.

CONCLUSIONS

Smartphone-based 3D facial scanning has been basically validated for clinical application, showing broad clinical application prospects in plastic surgery.

LEVEL OF EVIDENCE II

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 .

Intra-rater and inter-rater reliability of 3D facial measurements

Three-dimensional (3D) body scanning technology has applications for obtaining anthropometric data in human-centered and product development fields. The reliability of 3D measurements gathered from 3D scans must be assessed to understand the degree to which this technology is appropriate for use in place of manual anthropometric methods. The intra- and inter-rater reliabilities of 3D facial measurements were assessed among four novice raters using 3D landmarking. Intraclass correlation coefficient (ICC) statistics were calculated for the 3D measurement data collected in three phases to assess baseline reliabilities and improvements in reliabilities as the result of additional training and experience. Based on the results of this study, the researchers found that the collection of 3D measurement data, by multiple raters and using 3D landmarking methods, yielded a high percentage of ICC statistics in the good to excellent (>0.75 ICC) reliability range. Rater training and experience were important considerations in improving intra- and inter-rater reliabilities.

A comprehensive evaluation of the phenotype-first and data-driven approaches in analyzing facial morphological traits

The phenotype-first approach (PFA) and data-driven approach (DDA) have both greatly facilitated anthropological studies and the mapping of trait-associated genes. However, the pros and cons of the two approaches are poorly understood. Here, we systematically evaluated the two approaches and analyzed 14,838 facial traits in 2,379 Han Chinese individuals. Interestingly, the PFA explained more facial variation than the DDA in the top 100 and 1,000 except in the top 10 phenotypes. Accordingly, the ratio of heterogeneous traits extracted from the PFA was much greater, while more homogenous traits were found using the DDA for different sex, age, and BMI groups. Notably, our results demonstrated that the sex factor accounted for 30% of phenotypic variation in all traits extracted. Furthermore, we linked DDA phenotypes to PFA phenotypes with explicit biological explanations. These findings provide new insights into the analysis of multidimensional phenotypes and expand the understanding of phenotyping approaches.

"Utility of Smartphone-based Three-dimensional Surface Imaging for Digital Facial Anthropometry"

Background

The utilization of three-dimensional (3D) surface imaging for facial anthropometry is a significant asset for patients undergoing maxillofacial surgery. Notably, there have been recent advancements in smartphone technology that enable 3D surface imaging.In this study, anthropometric assessments of the face were performed using a smartphone and a sophisticated 3D surface imaging system.

Methods

30 healthy volunteers (15 females and 15 males) were included in the study. An iPhone 14 Pro (Apple Inc., USA) using the application 3D Scanner App (Laan Consulting Corp., USA) and the Vectra M5 (Canfield Scientific, USA) were employed to create 3D surface models. For each participant, 19 anthropometric measurements were conducted on the 3D surface models. Subsequently, the anthropometric measurements generated by the two approaches were compared. The statistical techniques employed included the paired t-test, paired Wilcoxon signed-rank test, Bland-Altman analysis, and calculation of the intraclass correlation coefficient (ICC).

Results

All measurements showed excellent agreement between smartphone-based and Vectra M5-based measurements (ICC between 0.85 and 0.97). Statistical analysis revealed no statistically significant differences in the central tendencies for 17 of the 19 linear measurements. Despite the excellent agreement found, Bland-Altman analysis revealed that the 95% limits of agreement between the two methods exceeded ±3 mm for the majority of measurements.

Conclusion

Digital facial anthropometry using smartphones can serve as a valuable supplementary tool for surgeons, enhancing their communication with patients. However, the proposed data suggest that digital facial anthropometry using smartphones may not yet be suitable for certain diagnostic purposes that require high accuracy.

De Novo Dissecting the Three-Dimensional Facial Morphology of 2379 Han Chinese Individuals

Phenotypic diversity, especially that of facial morphology, has not been fully investigated in the Han Chinese, which is the largest ethnic group in the world. In this study, we systematically analyzed a total of 14,838 facial traits representing 15 categories with both a large-scale three-dimensional (3D) manual landmarking database and computer-aided facial segmented phenotyping in 2379 Han Chinese individuals. Our results illustrate that homogeneous and heterogeneous facial morphological traits exist among Han Chinese populations across the three geographical regions: Zhengzhou, Taizhou, and Nanning. We identified 1560 shared features from extracted phenotypes, which characterized well the basic facial morphology of the Han Chinese. In particular, heterogeneous phenotypes showing population structures corresponded to geographical subpopulations. The greatest facial variation among these geographical populations was the angle of glabella, left subalare, and right cheilion (p = 3.4 × 10-161). Interestingly, we found that Han Chinese populations could be classified into northern Han, central Han, and southern Han at the phenotypic level, and the facial morphological variation pattern of central Han Chinese was between the typical differentiation of northern and southern Han Chinese. This result was highly consistent with the results revealed by the genetic data. These findings provide new insights into the analysis of multidimensional phenotypes as well as a valuable resource for further facial phenotype-genotype association studies in Han Chinese and East Asian populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00109-x.

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.

Anterior cerebral falx plane in MR images to estimate the craniofacial midline

Multiple methods have been proposed for evaluating the symmetry of facial contour by utilizing the median sagittal plane of the skull as a reference and measuring the maxillofacial region. To replace the manual mark point analysis method, we used the anterior cerebral falx plane in MRI images as an indicator of the craniofacial midline. The MRI examination data of 30 individuals were analyzed with a MeVisLab workstation. Two independent examiners performed 15 anthropometric measurements (4 angular, 11 linear) and compared the MRI-based anterior cerebral falx plane with the manual mark point analysis of the craniofacial midline estimation. All measurements were repeated after 3 weeks. Statistical analyses included the repeatability and reproducibility of the 2 methods based on intra-observer and inter-observer correlation coefficients (ICCs), respectively. Precision was estimated by intergroup comparison of the coefficient of variation. The anterior falx plane derived from the MRI data resulted in an intra-observer ICC of 0.869 ± 0.065 (range 0.733-0.936) and inter-observer ICC of 0.876 ± 0.0417 (0.798-0.932) for all measurements, showing significant correlations with the ICC values obtained by the mark point method (p < 0.05). The coefficient of variation showed that the precisions of the 2 methods were statistically comparable. We conclude that, for MRI-based craniofacial midline estimation, measurements made using the anterior cerebral falx plane are as precise, repeatable, and reproducible as those using the manual mark point analysis method. It has a high potential for application in radiation-free 3-dimensional craniofacial analysis.

What is the impact of miniscrew-assisted rapid palatal expansion on the midfacial soft tissues? A prospective three-dimensional stereophotogrammetry study

OBJECTIVES

To evaluate the midfacial soft tissue changes of the face in patients treated with miniscrew-assisted rapid palatal expansion (MARPE).

MATERIALS AND METHODS

3D facial images and intra-oral scans (IOS) were obtained before expansion (T0), immediately after completion of expansion (T1), and 1 year after expansion (T2). The 3D images were superimposed and two 3D distance maps were generated to measure the midfacial soft tissue changes: immediate effects between timepoints T0 and T1 and overall effects between T0 and T2. Changes of the alar width were also measured and dental expansion was measured as the interpremolar width (IPW) on IOS.

RESULTS

Twenty-nine patients (22 women, 7 men, mean age 25.9 years) were enrolled. The soft tissue in the regions of the nose, left of philtrum, right of philtrum, and upper lip tubercle demonstrated a statistically significant anterior movement of 0.30 mm, 0.93 mm, 0.74 mm, and 0.81 mm, respectively (p < 0.01) immediately after expansion (T0-T1). These changes persisted as an overall effect (T0-T2). The alar width initially increased by 1.59 mm, and then decreased by 0.08 mm after 1 year, but this effect was not significant. The IPW increased by 4.58 mm and remained stable 1 year later. There was no significant correlation between the increase in IPW and alar width (r = 0.35, p = 0.06).

CONCLUSIONS

Our findings indicate that MARPE results in significant but small changes of the soft tissue in the peri-oral and nasal regions. However, the clinical importance of these findings is limited.

CLINICAL RELEVANCE

MARPE is an effective treatment modality to expand the maxilla, incurring only minimal and clinically insignificant changes to the midfacial soft tissues.

Acquisition of Precision and Reliability of Modalities for Facial Reconstruction and Aesthetic Surgery: A Systematic Review

The foundation of reconstructive and cosmetic surgery is a confluence of advanced technologies, plethora of procedures, inventive modifications, and planned strategies. In surgical planning, the most crucial steps for treating a patient are evaluating the facial morphometry and recognizing the deviations from the baseline values of facial parameters. Various imaging and non-imaging modalities and sub-modalities contribute to diagnosis, treatment planning, and follow-up care. These techniques are an important milestone of pre-, peri-, and postoperative care in facial reconstruction. The current research aims to comprehensively explain imaging and non-imaging technologies encompassing both innovative and traditional approaches in facial reconstruction. PubMed, Scopus, and Web of Science were searched from 1990 to 2022, and systematic review was conducted in accordance with the PRISMA recommendations. Undoubtedly, various factors impact the selection of facial analysis acquisition approaches and their prospective. The surgical team must understand such modalities' potential for diagnosis and treatment. The evolution of three-dimensional imaging has been fueled because of the need for devices with high speed, small size, and several functions. Automation with more efficiency and precision is the way of the future for three-dimensional imaging. Stereophotogrammetry can clearly quantify the field of facial analysis. All the publications under consideration came to the same conclusion: Canfield's Vectra three-dimensional imaging devices can provide accurate, repeatable stereophotogrammetric pictures. Although a few minor mistakes were recorded, most examined devices are deemed reliable and accurate tools for Plastic surgeons.

Accuracy between 2D Photography and Dual-Structured Light 3D Facial Scanner for Facial Anthropometry: A Clinical Study

(1) Background: Facial scanners are used in different fields of dentistry to digitalize the soft tissues of the patient's face. The development of technology has allowed the patient to have a 3-dimensional virtual representation, facilitating facial integration in the diagnosis and treatment plan. However, the accuracy of the facial scanner and the obtaining of better results with respect to the manual or two-dimensional (2D) method are questionable. The objective of this clinical trial was to evaluate the usefulness and accuracy of the 3D method (a dual-structured light facial scanner) and compare it with the 2D method (photography) to obtain facial analysis in the maximum intercuspation position and smile position. (2) Methods: A total of 60 participants were included, and nine facial landmarks and five interlandmarks distances were determined by two independent calibrated operators for each participant. All measurements were made using three methods: the manual method (manual measurement), the 2D method (photography), and the 3D method (facial scanner). All clinical and lighting conditions, as well as the specific parameters of each method, were standardized and controlled. The facial interlandmark distances were made by using a digital caliper, a 2D software program (Adobe Photoshop, version 21.0.2), and a 3D software program (Meshlab, version 2020.12), respectively. The data were analyzed by SPSS statistical software. The Kolmogorov-Smirnov test revealed that trueness and precision values were normally distributed (p > 0.05), so a Student's t-test was employed. (3) Results: Statistically significant differences (p ≤ 0.01) were observed in all interlandmark measurements in the 2D group (photography) to compare with the manual group. The 2D method obtained a mean accuracy value of 2.09 (±3.38) and 2.494 (±3.67) in maximum intercuspation and smile, respectively. On the other hand, the 3D method (facial scanner) obtained a mean accuracy value of 0.61 (±1.65) and 0.28 (±2.03) in maximum intercuspation and smile, respectively. There were no statistically significant differences with the manual method. (4) Conclusions: The employed technique demonstrated that it influences the accuracy of facial records. The 3D method reported acceptable accuracy values, while the 2D method showed discrepancies over the clinically acceptable limits.

Accuracy of three-dimensional optical devices for facial soft-tissue measurement in clinical practice of stomatology: A PRISMA systematic review

BACKGROUND

The accuracy of 3-dimensional (3D) optical devices for facial soft-tissue measurement is essential to the success of clinical treatment in stomatology. The aim of the present systematic review was to summarize the accuracy of 3D optical devices used for facial soft-tissue assessment in stomatology.

METHODS

An extensive systematic literature search was performed in the PubMed/MEDLINE, Embase, Scopus and Cochrane Library databases for studies published in the English language up to May 2022 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Peer-reviewed journal articles evaluating the facial soft-tissue morphology by 3D optical devices were included. The risk of bias was performed using the Quality Assessment Tool for Diagnostic Accuracy Studies-2 guidelines by the 2 reviewers. The potential publication bias was analyzed using the Review Manager software.

RESULTS

The query returned 1853 results. A total of 38 studies were included in this review. Articles were categorized based on the principle of devices: laser-based scanning, structured-light scanning, stereophotogrammetry and red, green, blue-depth camera.

CONCLUSION

Overall, the 3D optical devices demonstrated excellent accuracy and reliability for facial soft-tissue measurement in stomatology. red, green, blue-depth camera can collect accurate static and dynamic 3D facial scans with low cost and high measurement accuracy. Practical needs and availability of resources should be considered when these devices are used in clinical settings.

Anthropometric data of an elderly Iranian population provides insights for system design

BACKGROUND

Anthropometric data should be considered for each major population age category, specifically because of the dimension changes occurring during ageing. In elderly subjects, the physical activities and their capabilities become limited. Therefore anthropometric reference data for equipment and system designs is necessary.

OBJECTIVES

The aim of the study was to collect data for the body dimensions of an elderly Iranian population and evaluate the related gender and age correlations.

METHODS

Nineteen body dimensions were manually measured on a sample size of 317 subjects (167 male and 150 female) from four provinces of Iran. A pilot preliminary test for assessing test-retest reliability on ten body dimensions using the Intraclass Correlation Coefficient (ICC2 :1)  was performed. Descriptive statistics were reported based on gender and independent samples t-tests to compare the anthropometric dimensions of both genders and age.

RESULTS

Results indicated higher dimensions in males, except for hip-breadth (p = 0.87). In all subjects, increasing age corresponded with: decreased standing shoulder height, eye height, and elbow height; and with sitting height and sitting knee height; while hip-breadth increased. Reliability was acceptable (ICC2.1 >0.88). In the elderly, as with adult subjects, there are significant gender differences in body dimensions, and this should be considered in equipment and system design. Furthermore, this study demonstrated both genders differences and the consequences of aging.

CONCLUSIONS

From this pilot data, product designers can consider the anthropometric characteristics for elderly Iranian subjects for equipment and system design.

A semi-automatic three-dimensional technique using a regionalized facial template enables facial growth assessment in healthy children from 1.5 to 5.0 years of age

Objectives

To develop a semi-automatic technique to evaluate normative facial growth in healthy children between the age of 1.5 and 5.0 years using three-dimensional stereophotogrammetric images.

Materials and Methods

Three-dimensional facial images of healthy children at 1.5, 2.0, 2.5, 3.0, 4.0 and 5.0 years of age were collected and positioned based on a reference frame. A general face template was used to extract the face and its separate regions from the full stereophotogrammetric image. Furthermore, this template was used to create a uniform distributed mesh, which could be directly compared to other meshes. Average faces were created for each age group and mean growth was determined between consecutive groups for the full face and its separate regions. Finally, the results were tested for intra- and inter-operator performance.

Results

The highest growth velocity was present in the first period between 1.5 and 2.0 years of age with an average of 1.50 mm (±0.54 mm) per six months. After 2.0 years, facial growth velocity declined to only a third at the age of 5.0 years. Intra- and inter-operator variability was small and not significant.

Conclusions

The results show that this technique can be used for objective clinical evaluation of facial growth. Example normative facial averages and the corresponding facial growth between the age 1.5 and 5.0 years are shown.

Clinical Relevance

This technique can be used to collect and process facial data for objective clinical evaluation of facial growth in the individual patient. Furthermore, these data can be used as normative data in future comparative studies.

Longitudinal composite 3D faces and facial growth trends in children 6-11 years of age using 3D cephalometric surface imaging

BACKGROUND

Normative craniofacial anthropometry provides clinically important reference values used in the treatment of craniofacial conditions. Few objective datasets of normative data exist for children.

AIM

To establish normative data regarding craniofacial morphology changes with growth in children.

SUBJECTS AND METHODS

3D surface images of the same group of healthy children aged 6 - 11 years old recruited from a Dallas school were taken annually between the years 2015 - 2020. Composite 3D cephalometric faces were created for boys and girls of each age. General and craniofacial anthropometric measurements were compared.

RESULTS

Seven hundred ninety one individual stereophotogrammetric acquisitions were used (400 boys, 391 girls) taken from 180 children. Linear facial, orbital, nasal, and oral anthropometric measurements revealed a consistent increase in magnitude with age. Composite 3D face comparisons revealed prominent vertical and anteroposterior growth trends in the lower and upper facial regions.

CONCLUSION

This study presents a longitudinal 3D control dataset of the same group of children over a 6-year period that can serve as reference norms for facial growth values and trends in children aged 6-11 years. The composite 3D normative faces are available for clinical and research purposes upon request, which may be interrogated and measured according to user need and preference.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Three-dimensional facial scanner in the hands of patients: validation of a novel application on iPad/iPhone for three-dimensional imaging

Background

Three-dimensional (3D) photography plays an important role in surgical planning and postoperative evaluation. Commercial 3D facial scanners are expensive, and they require patients to come to the clinics for 3D photography. To solve this problem, we developed an iPad/iPhone application to enable patients to capture 3D images of themselves on their own. This study aimed to evaluate the validity and reproducibility of this novel imaging system.

Methods

3D images were taken on 20 volunteers using the novel imaging system. Twenty-one anthropometric parameters were measured using calipers (direct measurement) and 3D photographs (3D photogrammetry). The results were compared to assess the accuracy and bias of 3D photogrammetry. The reproducibility was evaluated by testing intra- and interobserver reliabilities. Furthermore, 3D virtual models obtained by the novel imaging system and Vectra H1 camera were compared by performing heat map analysis.

Results

The 3D photogrammetric results showed excellent correlations with direct measurements. Most anthropometric parameters did not show statistically significant differences between the two methods. The 95% limits of agreement exceeded 2 mm in some parameters, especially those with large numbers, although their relative error measurements were very small. Intra- and interobserver reliabilities were high enough to ensure good reproducibility. The comparison of 3D models obtained by the novel imaging system and Vectra H1 camera showed that the mean distance and the mean RMS were 0.08 and 0.67 mm, respectively.

Conclusions

The novel 3D facial scanning system is validated to enable patients to take 3D images on their own. The imaging quality of the subnasale region needs further improvement. Future clinical applications include surgical planning, postoperative evaluation, and early diagnosis of diseases that affect facial appearance.

Three-dimensional nasolabial changes after maxillary advancement osteotomy in class III individuals: a systematic review and meta-analysis

Background Class III malocclusions with maxillary retrognathia are commonly treated with single jaw Le Fort I maxillary advancement. The three-dimensional (3D) effects of surgery on the nasolabial region varies among the clinical studies. Quantifying these changes is of great importance for surgical planning and obtaining valid consent. Objectives To investigate the 3D relationship between soft tissue and skeletal changes secondary to Le Fort I maxillary advancement surgery in skeletal class III patients.Search methods Comprehensive search of multiple electronic databases supplemented by a manual and grey literature search were undertaken from inception to 9 June 2020.Selection criteria Studies that evaluated the 3D soft tissue changes of patients before and after maxillary advancement surgery alone.Data collection and analysis Study selection, data extraction and risk of bias assessment were performed independently by two reviewers, with disputes resolved by a third reviewer. A quantitative synthesis of the data was pre-planned for pooling similar outcome measures.Results Four studies were included in the final review and meta-analysis, with a total of 105 patients (mean age 16.7 + 33.9 years). The mean maxillary advancement of the included studies was 5.58 mm (95% CI 5.20-5.96). The sagittal effects of surgery on nose tip projection and prominence were insignificant (P >0.05, two studies); however, subnasal projection (MD 1.7 mm, two studies) and upper lip projection (MD 2.90 mm, four studies) increased significantly in a forward direction after surgery (P <0.05). Le Fort I osteotomy widens the upper philtrum width (MD 0.84 mm, two studies) (P <0.05). Inconsistencies among the included studies were identified; therefore, the results should be interpreted with caution.Conclusions There is weak evidence based on quantitative assessments that Le Fort I maxillary advancement significantly affects the nasolabial soft tissue envelope mainly in a sagittal dimension. These changes are concentrated around the central zone of the nasolabial region. Future prospective studies on maxillary advancement osteotomy with a standardised method of assessment, taking into consideration the confounding factors, are required.

Tooth-borne versus tooth-bone-borne rapid maxillary expanders according to a stereophotogrammetric evaluation of facial soft tissues: A randomized clinical trial

OBJECTIVES

To evaluate the effects of tooth-borne and tooth-bone-borne rapid maxillary expansion (RME) on soft tissue with stereophotogrammetry.

SETTING AND SAMPLE POPULATION

Thirty two patients (15 males and 17 females) who met inclusion criteria were divided into two groups. In the first group, tooth-borne RME appliance (hyrax) was applied to 16 patients (9 males and 7 females mean age 13.4 ± 1.3 years), and in the second group, tooth-bone-borne RME appliance (hybrid hyrax) was applied to 16 patients (6 males and 10 females, mean age 13.05 ± 1.24 years).

MATERIALS AND METHODS

Changes in soft tissues before RME (T0) and post-retention (T1) period were evaluated by stereophotogrammetry. Linear and angular measurements were performed. Independent- and dependent-sample t tests were used to compare intra- and inter-group differences at P < .05 significance level.

RESULTS

The data revealed statistically significant changes in nasal width, mid-face width, upper lip vermillion length/lower lip vermillion length ratio and upper lip angle in hyrax group. (P < .05) Also nasal width, lower lip length, lower lip vermillion length, anterior face height, lower face height, convexity angle and mandibular angle showed statistically significant changes in hybrid hyrax group. (P < .05) In the inter-group evaluation, no significant differences were found except upper lip and mandible angle. (P < .05).

CONCLUSION

Both hyrax and hybrid hyrax expanders had effects on soft tissue profile. Anterior face height and lower face height increased in both groups. Upper lip length increased by 0.36 mm in the hybrid group and 0.10 mm in the hyrax group.

TRIAL REGISTRATION

This trial was registered at Clinicaltrials.gov (Identifier: NCT04828213).

Updating Standards of Facial Growth in Romanian Children and Adolescents Using the Anthropometric Method-A Pilot Study

The anthropometric method is an important tri-dimensional and non-invasive assessment instrument for accurate diagnosis in paedodontics, orthodontics, and other medical fields. Our aim was to propose a technique that is accessible for clinicians and to determine the reference values for Romanian children and adolescents for the facial parameters selected. We proposed three basic instruments: a plastic compass, a ruler, and a digital caliper. Eighty-five children and adolescents (62% girls and 38% boys), aged between 3.5 and 14.5 years, were included in the study. We selected eight transversal, 12 vertical, and three sagittal measurements. Facial indices, according to Farkas L.G., were directly determined. The correlations between facial and general growth parameters, using Pearson correlation coefficient, for the entire sample were significant, direct, and strong for the following: Zy-Zy, Go-Go, N-Gn, N-Sn, Sto-Gn, Tr-Gn, Tr-Sn, Tr-Tr (r = 0.526–0.925, p < 0.001), and insignificant for Sn-Sto (r = 0.099–0.124, p > 0.354). The highest correlation coefficient is exhibited by Tr-Gn (r = 0.893 with height and r = 0.925 with weight). When performing a gender related comparison, we noticed that the vertical and transversal linear parameters and some facial indices are increased in boys (p < 0.05), depending on the age group. The simplified anthropometric technique represents an accessible method to every clinician, bringing important information related to dentofacial growth, diagnosis, and treatment planning in dentistry.

Three-Dimensional Facial Anthropometric Analysis With and Without Landmark Labelling: Is There a Real Difference?

INTRODUCTION

The actual role of landmarks labeling before three-dimensional (3D) facial acquisition is still debated. In this study, several measurements were compared among textured labeled (TL), unlabeled (NL), and untextured (NTL) 3D facial models.

MATERIALS AND METHODS

The face of 50 subjects was acquired through stereophotogrammetry. Landmark coordinates were extracted from TL, NL, and NTL facial models, and 33 linear and angular measurements were calculated, together with surface area and volume. Accuracy of measurements among TL, NL, and NTL models was assessed through calculation of relative technical error of measurement (rTEM). The intra- and inter-observer errors for each type of facial model were calculated.

RESULTS

Intra- and inter-observer error of measurements increased passing from textured to NTL and NL 3D models. Average rTEMs between TL models, and NTL and NL models were 4.5 ± 2.6% and 4.7 ± 2.8%, respectively, almost all measurements being classified as "very good" or "good." Only for orbital height and its inclination, mandibular ramus length, nasal convexity, alar slope angle, and facial divergence, rTEM was classified as "moderate" or "poor."

CONCLUSIONS

Accuracy and precision of measurements decrease when landmarks are not previously labeled; attention must be taken when measurements have a low magnitude or involve landmarks requiring palpation.

Evaluation of facial asymmetry by stereophotogrammetry in individuals with unilateral maxillary impacted canine

PURPOSE

The aim of this study is to compare the symmetry of the facial and dentoalveolar structures of patients with unilateral impacted maxillary canine teeth with a control group of individuals without impacted teeth using three-dimensional face scans.

METHODS

The study included 28 patients (10 females, 18 males) with unilateral impacted maxillary canine teeth and 28 patients (15 females, 13 males) without any impacted maxillary canine between 12 and 25 years of age. The 3dMDface™ (3dMD Inc., Atlanta, GA, USA) imaging system was used to obtain 3D face images. 3dMD Vultus® (3dMD Inc., Atlanta, GA, USA) software was used for the measurements.

RESULTS

According to the study findings, there were differences in linear measurements and volume measurements between the right and left sides of the face in patients with an impacted canine. However, these differences were not statistically significant. In patients with an impacted canine, surface differences between the right and left halves of the face were not found to be statistically different from the control group.

CONCLUSION

There was no difference in the amount of facial asymmetry between patients with unilateral maxillary impacted canine and patients with normal tooth alignment in the control group.

Accuracy of three-dimensional photogrammetry and cone beam computed tomography based on linear measurements in patients with facial deformities

OBJECTIVES

This study was aimed to investigate the accuracy of soft-tissue measurements obtained by two imaging modalities, three-dimensional (3D) photogrammetry and cone beam CT (CBCT) when confounded by influence factors (facial deformities and partitions).

METHODS

60 wax facial models from facially deformed patients were captured by 3D photogrammetry and CBCT. 19 linear distances on each image were measured and juxtaposed to reference values attained via a coordinate-measuring machine (CMM) as the gold-standard. Paired t-tests were used to compare linear accuracy of the test and reference systems. The influence of deformities and partitions (created by dividing the face with three vertical and five horizontal lines) on the measurement errors were analyzed by independent sample t-test and one-way ANOVA.

RESULTS

Statistically significant differences were found between linear accuracy of the test and reference systems. The test values obtained by 3D photogrammetry were closer to the reference values than CBCT's. 3D photogrammetry's measurement errors were significantly higher in deformed areas, unlike CBCT's. Both systems reported significantly lower errors within partitions 8 and 13 compared to other partitions; for CBCT, aside from partitions 8 and 13, the differences in the errors for partitions 6 and 10 were significant compared to partitions 8, 12, 13, 14.

CONCLUSION

3D photogrammetry showed a higher linear accuracy than CBCT in patients with facial deformities due to protuberances. Facial reconstruction by both test modalities was significantly influenced in different facial partitions, but facial deformities extensively affected the results from 3D photogrammetry.

Reliability and Agreement of 3D Anthropometric Measurements in Facial Palsy Patients Using a Low-Cost 4D Imaging System

The reliability (precision) and agreement (accuracy) of anthropometric measurements based on manually placed 3D landmarks using the RealSense D415 were investigated in this paper. Thirty facial palsy patients, with their face in neutral (resting) position, were recorded simultaneously with the RealSense and a professional 3dMD imaging system. First the RealSense depth accuracy was determined. Subsequently, two observers placed 14 facial landmarks on the 3dMD and RealSense image, assessing the distance between landmark placement. The respective intra- and inter-rater Euclidean distance between the landmark placements was 0.84 mm (±0.58) and 1.00 mm (±0.70) for the 3dMD landmarks and 1.32 mm (±1.27) and 1.62 mm (±1.42) for the RealSense landmarks. From these landmarks 14 anthropometric measurements were derived. The intra- and inter-rater measurements had an overall reliability of 0.95 (0.87 - 0.98) and 0.93 (0.85 - 0.97) for the 3dMD measurements, and 0.83 (0.70 - 0.91) and 0.80 (0.64 - 0.89) for the RealSense measurements, respectively, expressed as the intra-class correlation coefficient. Determined by the Bland-Altman analysis, the agreement between the RealSense measurements and 3dMD measurements was on average -0.90 mm (-4.04 - 2.24) and -0.89 mm (-4.65 - 2.86) for intra- and inter-rater agreement, respectively. Based on the reported reliability and agreement of the RealSense measurements, the RealSense D415 can be considered as a viable option to perform objective 3D anthropomorphic measurements on the face in a neutral position, where a low-cost and portable camera is required.

Short-term impact of microimplant-assisted rapid palatal expansion on the nasal soft tissues in adults: A three-dimensional stereophotogrammetry study

Objective

The aim of this study was to evaluate changes in the nasal soft tissues, including movements of landmarks, changes in linear distances, and volumetric changes, using three-dimensional (3D) stereophotogrammetry after microimplant-assisted rapid palatal expansion (MARPE) in adult patients.

Methods

Facial data were scanned using a white light scanner before and after MARPE in 30 patients. In total, 7 mm of expansion was achieved over a 4-week expansion period. We determined 10 soft tissue landmarks using reverse engineering software and measured 3D vector changes at those points. In addition, we calculated the distances between points to determine changes in the width of the nasal soft tissues. The volumetric change in the nose was also measured.

Results

All landmarks except pronasale and subnasale showed statistically significant movement on the x-axis. Pronasale, subnasale, alar right, and alar left showed significant movement on the y-axis, while all landmarks except subnasale showed significant movement on the z-axis. The alar base width, alar width, and alar curvature width increased by 1.214, 0.932, and 0.987 mm, respectively. The average volumetric change was 993.33 mm³, and the amount of increase relative to the average initial volume was 2.96%.

Conclusions

The majority of soft tissue landmarks around the nasal region show significant positional changes after MARPE in adults. The nose tends to widen and move forward and downward. The post-treatment nasal volume may also exhibit a significant increase relative to the initial volume. Clinicians should thoroughly explain the anticipated changes to patients before MARPE initiation.

Craniofacial Anthropometry: Normative Data for Caucasian Infants

PURPOSE

Craniofacial anthropometry is a valuable tool for characterization of facial dysmorphology and evaluation of treatment outcomes. Databases of normal anthropometric ranges are limited for infants. The aim of this study is to establish normative data for craniofacial anthropometric measurements in Caucasian infants.

METHODS

This is a prospective cross-sectional study including Caucasian infants (≤12 months old) that were recruited from a pediatric medicine practice and Boston Children's Hospital. Infants with craniofacial deformities, trauma or operations were excluded. The sample was stratified by age (in months) into 4 groups: 0 to 3, 3.1 to 6, 6.1 to 9, and 9.1 to 12. Three dimensional (3D) photographs were obtained for all subjects. Forty-five standard anthropometric points were plotted, and 37 measurements were made on the 3D photographs. Two evaluators independently performed all measurements. One examiner repeated the measurements on 25% of the subjects. Intraclass correlation coefficients (ICC) were calculated to assess inter-rater and intra-rater agreement.

RESULTS

Thirty-three subjects were enrolled in the study. The mean age for the entire sample was 6.3 ± 3.0 months, and 17 subjects (52%) were female. The mean ages (months) for each group were: 1.9 ± 0.7 for group 1 (n = 6); 4.4 ± 0.7 for group 2 (n = 8); 7.5 ± 1.1 for group 3 (n = 11); and 9.9 ± 1.0 for group 4 (n = 8). Descriptive statistics are presented for each group. Inter- and intra-rater agreements were acceptable (ICC >0.6) for 21 anthropometric measurements.

CONCLUSIONS

This study generated normative craniofacial anthropometric measurements for Caucasian infants. These data can be used in the interpretation of measurements for research studies evaluating craniofacial anomalies in this population.

Association between Gingival Biotype and Facial Typology through Cephalometric Evaluation and Three-Dimensional Facial Scanning

In dentistry, the assessment of periodontal biotype is considered one of the most important parameters with which to plan treatment, and craniofacial morphology might affect it. The aim of this study was to investigate the association between facial typology and gingival biotype in patients by means of two-dimensional and three-dimensional evaluations of facial typology. This study included 121 participants searching for orthodontic treatment (43 M, 78 F; 20.4 ± 10.4). Gingival biotype was evaluated based on the transparency of the periodontal probe through the gingival margin of the mid-buccal sulcus for both upper (UGB) and lower (LGB) anterior teeth. SellionNasion^GonionGnation (SN^GoGn) and CondylionGonionMenton (CoGoMe^) angles were measured on two-dimensional cephalograms. Three-dimensional face scans were acquired by means of a three-dimensional facial scanner (3dMD system) and successively analyzed to assess the facial typology using the ratio between lower facial height (SNMe) and total facial height (NMe). A chi-squared test and regression analysis were used to evaluate the associations between gingival biotype and facial morphology (p < 0.05). The chi-squared test showed that there was no statistically significant association between facial typology and gingival biotype (UGB p = 0.83; LGB p = 0.75). The logistic regression showed an association between SNMe/NMe and the UGB (p = 0.036), and SNMe/NMe and LGB (p = 0.049). The decreased ratio of SNMe/NMe might be a protective factor for a thin gingival biotype.

Validity and reproducibility of the 3D VECTRA photogrammetric surface imaging system for the maxillofacial anthropometric measurement on cleft patients

OBJECTIVES

To validate the accuracy and reproducibility of linear measurements of three-dimensional (3D) images and to compare the measurements with the direct anthropometry method on cleft lip and palate (CLP) patients.

MATERIALS AND METHODS

Nineteen linear facial measurements were derived from 16 standardized surface landmarks obtained from 37 cleft patients (20 males, 17 females; mean age 23.84 years, standard deviation ± 6.02). They were taken manually with calipers and were compared with the digitally calculated distance on the 3D images captured using the VECTRA-M5 360° Imaging System with pre-marked landmarks. Another pair of 19 linear measurements were computed on the 3D images 2 weeks apart for intra- and inter-observer agreements. Statistical analyses used were paired t test, the Bland-Altman analysis, and the intra-class correlation coefficient (ICC) index.

RESULTS

Most of the linear measurements showed no statistically significant differences between the proposed method and direct anthropometry linear measurements. Nevertheless, bias of the 3D imaging system is present in the linear measurements of the nose width and the upper vermillion height. The measurements' mean biases were within 2 mm, but the 95% limit of agreement was more than 2 mm. Intra- and inter-observer measurements generally showed good reproducibility. Four inter-observer measurements, the upper and lower face heights, nose width, and pronasale to left alar base were clinically significant.

CONCLUSIONS

Measurements obtained from this 3D imaging system are valid and reproducible for evaluating CLP patients.

CLINICAL RELEVANCE

The system is suitable to be used in a clinical setting for cleft patients. However, training of the operator is strictly advisable.

Three-Dimensional Nasal Alterations in Le Fort I Advancement: Linear Measurements, Angles, Nasal Indices, and Volume Differences

The maxillary advancement obtained by the Le Fort I osteotomy can also generate significant changes in the soft tissue of the nose and lips. The aim of this study was to compare the alterations in the soft tissue of the nose following the Le Fort I osteotomy maxillary advancement technique in a population of young adults submitted to orthognathic surgery. Seven men and 8 women aged between 23 and 45 underwent orthognathic surgery using the Le Fort I osteotomy and bilateral mandibular sagittal osteotomy. Sixty 3-dimensional images were analyzed (Vectra M3, Canfield, NJ) after labeling landmarks on the face and determining linear and angular measurements, proportion, and volume difference indices at the following intervals: preoperatively (baseline), then 2 months, 6 months, and 1 year after surgery. Following Le Fort I, there was an increase in the alar base, and reduction of nasal tip protrusion, nasal angles, and the nasal tip protrusion index (P < 0.05). There were no differences in the facial thirds, the nasal index, and angles of nasal and mentolabial convexity (P > 0.05). There was a difference in the volume of the nose only 2 months after surgery. The Le Fort I osteotomy caused significant alterations in linear, angular, and nasal proportion measurements. The volume differences were reversible in the early postoperative period and probably associated with edema. The possibility of variations in the size and shape of the nose should be presented to prospective patients preoperatively.

Three-dimensional analysis of lip changes in response to simulated maxillary incisor advancement

OBJECTIVE

To assess the immediate response of lips in three dimensions (3D) resulting from simulated maxillary incisor advancement.

MATERIALS AND METHODS

Incremental maxillary incisor advancement was simulated by placing wax of increasing thickness (+2 mm, +4 mm, +6 mm) on the incisors of 20 participants, and the induced lip changes were recorded using 3D stereophotogrammetry. The induced displacement of lip landmarks was quantified using 3D image analysis software. Data were analyzed using a repeated-measures analysis of variance (ANOVA) after adjusting for age and sex of the study participants.

RESULTS

A large interindividual variation in lip response to simulated incisor advancement was observed. A significant overall effect on 3D lip changes was found for increasing values of simulated incisor advancement (F = 13.2; P < .001) as well as significant differences between anatomical landmarks of the lip (F = 7.4; P < .01). Most points moved outward and anterosuperiorly, except the midpoint and corners of the lip. Greatest movement was observed in the sagittal plane, followed by the vertical and transverse planes.

CONCLUSIONS

Maxillary incisor advancement significantly affects upper lip change in three planes of space: particularly the anteroposterior plane, in which the response to simulated advancement appears to be nonlinear.

A comparison between 2D and 3D methods of quantifying facial morphology

Objectives

Currently, two & three-dimensional (2D & 3D) imaging techniques have largely replaced the direct anthropometric method in the assessment of facial morphology, but the difference between the two techniques was not quantified. Therefore, the aim of this study was to compare and quantify (the difference between) the two techniques.

Materials and methods

The faces of 150 subjects (75 males, 75 females) of northern Nigeria, predominantly Hausa ethnic group, were photographed (using digital camera) and scanned (using a 3D surface laser scanner). Facial dimensions were generated from the resulting virtual 2D and 3D models. Data were analyzed using R-statistic software & Paired sample t-test/Pearson correlation were conducted to compare the two methods and to quantify the level of closeness between the two measurements.

Results

Intraclass correlation coefficient (ICC) was very low (0.26) for the 3D and 2D measurements indicating the level of differences between the methods. Measurements taken with laser scanner were higher relative to the one taken by camera. The mean differences between the 3D and the 2D methods of quantifying facial morphology indicated a statistically significant positive difference. CONCLUSION: 2D and 3D anthropometry cannot be used interchangeably since there exists statistically significant variation between the two methods.

High-Fidelity Anthropometric Facial Measurements Can Be Obtained From a Single Stereophotograph From the Vectra H1 3-Dimensional Camera

BACKGROUND

Anthropometry is a well-established means of measuring facial morphology. Although reliable, direct anthropometry can be time-consuming and not conducive to a busy clinical practice. The Vectra H1 handheld stereophotogrammetric system requires 3 stereophotographs taken from different perspectives to generate a three-dimensional (3D) surface. The time needed to take the 3 stereophotographs can increase the possibility of involuntary movements, precluding its use to assess young patients. To overcome this limitation, we evaluated if accurate linear facial measurements can be obtained from a single stereophotograph and compare these to the measurements taken by direct anthropometry.

METHODS

Twenty pediatric patients, aged 0 to 10 years, who were undergoing minor surgical procedures at Johns Hopkins All Children's Hospital were recruited. Fourteen linear facial distances were obtained from each participant using direct anthropometry under general anesthesia. These same distances were measured using Mirror 3D analysis. Intraclass correlation was used to determine intrarater reliability on duplicate 3D images.

RESULTS

Correlation coefficients between 3D imaging in frontal view and direct anthropometric measurements were excellent for 13 measures taken, ranging from 0.8 (subnasale to columella and subnasale to stomion superius) to 0.98 (nasion to subnasale and subnasale to labiale superius). Correlation coefficients between submental view and direct anthropometric measurements were excellent for 13 measures as well, ranging from 0.77 (subnasale to columella) to 0.98 (nasion to subnasale).

CONCLUSIONS

Linear anthropometric measurements taken from 3D surfaces generated from a single stereophotograph correlate closely with direct anthropometric measures. This improves workflow and applicability of anthropometric studies to our youngest patients.

[Accuracy of three-dimensional camera system based on stereophotography on photographic acquisition of deformity facial images]

OBJECTIVE

To evaluate and analyze the accuracy of three-dimensional camera system acquisition based on stereophotography for the photographic acquisition of images of facial deformities.

METHODS

3D digital models of 45 waxen facial models of patients with facial deformities were obtained via a 3D camera system based on stereophotography. A total of 19 feature lines were measured on each 3D model by using the software. The measurements taken by the coordinate-measuring machine were accepted as standard values. Statistical analysis was performed to evaluate the accuracy of the system and the corresponding factors.

RESULTS

Statistical analysis results showed that the measured values of the characteristic distance obtained by 3D camera system were statistically different from the standard values (P<0.001). Convex deformities had significant influence on the measuring error of 3D camera system (P<0.05), while cleft deformities had no significant influence on the measuring error (P>0.05). The facial regions significantly influenced measuring error (P<0.05). The deformities had no significant influence on the percentage of measurement values (P>0.05). The middle facial regions had significant difference with bilateral facial regions on the percentage of measurement values (P<0.05), while the left and right facial regions had no significant difference (P>0.05).

CONCLUSIONS

The accuracy of 3D camera system based on stereophotography for the photographic acquisition of facial deformities are influenced by the morphology of the facial deformities and facial regions. Moreover, the measuring error is acceptable in clinical settings.

Soft tissue changes: a comparison between changes caused by the construction bite and by successful treatment with a modified Twin-block appliance

Background/objectives

Functional appliances are commonly used to correct Class II malocclusion. This study aimed to compare the facial soft tissue changes in Caucasians between pre-treatment and with the construction bite versus pre-treatment and completion of treatment with a modified Twin-block appliance (MTBA).

Materials and methods

Fifty-eight Caucasian subjects with Class II division 1 malocclusion had 3D stereophotogrammetric images captured pre-treatment (T1), with the construction bite (T2), and on completion of MTBA treatment (T3). Twenty-six landmarks were located on each image and 10% were re-landmarked 1 month later. Soft-tissue linear and volumetric changes (T1-T2 and T1-T3) were analyzed using linear mixed effect models (SAS® Version 9.4, www.sas.com).

Results

Forty-seven subjects [mean age 13.2 (SD 1.7) years] completed treatment [mean duration 9.8 (SD 3.8) months]. Differences between the changes from T1 to T2 versus T1 to T3 for upper facial and upper lip landmarks were insignificant (all P > 0.05) except for nasion, orbitale right, pronasale, and subnasale. For the same comparisons, lower lip and chin landmarks changed significantly (all P < 0.05) as did facial soft tissue volume (P< 0.0001).

Limitations

There was no control group.

Conclusion

The facial soft tissue changes from pre-treatment to with the construction bite were considerably more than those from pre-treatment to completion of treatment with a MTBA.

Implication

With MTBA treatment, the soft tissue changes from pre-treatment to with the construction bite in situ, overestimate those from pre- to post-treatment.

Accuracy evaluation of tridimensional images performed by portable stereophotogrammetric system

Abstract Introduction Human facial characteristics vary according to individual dental occlusion, facial harmony, orofacial musculature and the format and configuration of craniofacial structures. Traditionally, anthropometric measurements have been acquired through direct evaluation of subjects in a clinical environment using calipers and metric tapes to measure distances between arches and landmarks. Scientific breakthroughs have enabled the digitization of data and introduced the possibility of quick, precise, radiation-free acquisitions; details can be archived for future analysis and easily shared with patients and colleagues. Among new facial analysis methods, the stereophotogrammetry technique has emerged, which uses a group of cameras to take many photographs of a subject in rapid succession from multiple angles. Nowadays, portable stereophotogrammetric systems are being proposed, as they are more practical and easier to use. Objective The aim of this work was to analyze the accuracy and reproducibility of a portable 3D stereophotogrammetric system (Vectra H1, Canfield, Fairfield, NJ, USA) in measuring soft facial tissues of 30 participants, defining measures of a cube and comparing these measurements with those obtained by a set 3D stereophotogrammetric system (Vectra M3, Canfield, Fairfield, NJ, USA) with previously validated accuracy and reproducibility through quantitative analysis of possible errors. Material and method Thirty temporary landmarks were used to measure (in mm) 34 distances in 30 participants (n = 30). Regarding the cube, 12 angles and 9 linear distances were evaluated. Result The results obtained by the established methodology indicated that the Vectra H1 portable system has shown accuracy and reproducibility equal to that of the Vectra M3 set system. Conclusion Data analysis and correlation to literature findings show Vectra H1's capability to reliably capture tridimensional images, which makes it practical for use in diverse clinical applications.

The role of Nasoalveolar molding: A 3D Prospective analysis

Nasoalveolar molding (NAM) is commonly employed to reduce the alveolar segments into proper alignment and to improve nasal symmetry in patients with cleft lip and palate. This study examines the periodical progression of NAM treatment over time. 20 patients with complete unilateral cleft lip and palate were prospectively recruited. A 2 stage NAM treatment protocol was applied. Stage 1 involved adjustment of the alveolar segments (mean age 15.6 days), while Stage 2 added nasal stents and started average 43 days after stage 1. 3D images (n = 241) were obtained prior to NAM initiation and weekly until the end of treatment. The cleft lip area, bilateral nostril areas, and the nostril height and width were measured. Treatment was assessed in the Cleft (C) side and the Non-cleft (N). There was significant difference in the C/N ratio of the nostril area, width, and height at pre-treatment (0.9 ± 0.3, 4.1 ± 1.1, and 0.5 ± 0.2), at the end of stage 1 (1.1 ± 0.3, 2.2 ± 0.6, and 0.8 ± 0.2), and at the end of stage 2 treatment (1.8 ± 0.3, 1.8 ± 0.4, and 1.2 ± 0.1); p < 0.05. Comparative 3D analysis with dense sampling offers a precise methodology for showing effects of NAM treatment. The morphological changes achieved with NAM therapy occur in early treatment phase.

Validation of a new three-dimensional imaging system using comparative craniofacial anthropometry

Background

The aim of this study is to validate a new three-dimensional craniofacial stereophotogrammetry imaging system (3dMDface) through comparison with manual facial surface anthropometry. The null hypothesis was that there is no difference between craniofacial measurements using anthropometry vs. the 3dMDface system.

Methods

Facial images using the new 3dMDface system were taken from six randomly selected subjects, sitting in natural head position, on six separate occasions each 1 week apart, repeated twice at each sitting. Exclusion criteria were excess facial hair, facial piercings and undergoing current dentofacial treatment. 3dMDvultus software allowed facial landmarks to be marked and measurements recorded. The same measurements were taken using manual anthropometry, using soluble eyeliner to pinpoint landmarks, and sliding and spreading callipers and measuring tape to measure distances. The setting for the investigation was a dental teaching hospital and regional (secondary and tertiary care) cleft centre. The main outcome measure was comparison of the craniofacial measurements using the two aforementioned techniques.

Results

The results showed good agreement between craniofacial measurements using the 3dMDface system compared with manual anthropometry. For all measurements, except chin height and labial fissure width, there was a greater variability with the manual method compared to 3D assessment. Overall, there was a significantly greater variability in manual compared with 3D assessments (p < 0.02).

Conclusions

The 3dMDface system is validated for craniofacial measurements.

A three-dimensional photogrammetric analysis of the facial esthetics of the Miss Korea pageant contestants

Objective

The aims of this study were to measure and compare the facial dimensions of the Miss Korea pageant contestants and a selected group of women from the general population by using three-dimensional (3D) image analysis, as well as to compare various facial ratios to the golden ratio within each group.

Methods

Three-dimensional images of 52 Miss Korea pageant contestants (MK group) and 41 young female adults selected from the general population (GP group) were acquired. Fifty-four variables and ratios were measured and calculated. Intergroup comparisons were performed using multivariate analysis of variance.

Results

Compared to the GP group, the MK group showed greater total facial height and eye width, lesser lower-facial height, and lesser facial, lower-facial, and nasal widths. Moreover, compared to the GP group, the MK group had more protruded noses with greater nasolabial angle, greater vertical curvature of the foreheads, lesser horizontal curvature of the cheek, and lesser lower-lip-and-chin volume.

Conclusions

The MK group had longer faces but smaller lower lips and chins than did the GP group. The golden ratio was not matching the current facial esthetic standards. These data might be beneficial for treatment planning of patients undergoing orthognathic and plastic surgeries.

Evaluation of soft tissue changes around the lips after bracket debonding using three-dimensional stereophotogrammetry

OBJECTIVE

To evaluate the changes in soft tissue around the lips after orthodontic bracket debonding using three-dimensional (3-D) stereophotogrammetry.

MATERIALS AND METHODS

3-D facial images of 20 subjects (10 men and 10 women; mean age, 26.81 ± 7.23 years) were taken with a white light scanner before and after debonding the labial brackets. Two images acquired from each subject were superimposed, and 15 soft tissue landmarks around the lips were plotted and analyzed. Statistical analysis was performed using both paired and independent t-tests (P < .05).

RESULTS

There were no significant changes in position of any landmark on the x (left-right)- or y (vertical)-axes after removal of the brackets. However, the landmarks in the oral commissures and lower lip (LLP, -0.55 mm; Li, -0.44 mm; Ch-L, -0.56 mm, all P < .05) on the z (anteroposterior)-axis showed statistically significant differences. There were no significant positional changes of most landmarks on the x-, y-, or z- axes after bracket removal among the various genders and lip thicknesses.

CONCLUSIONS

There was a slight retrusion in the oral commissure and lower lip areas after debonding, but no changes were found in the upper lip area. This study showed that 3-D stereophotogrammetry can be useful in evaluating facial soft tissue changes in orthodontic patients.

The 3D Tele Motion Tracking for the Orthodontic Facial Analysis

Aim. This study aimed to evaluate the reliability of 3D-TMT, previously used only for dynamic testing, in a static cephalometric evaluation. Material and Method. A group of 40 patients (20 males and 20 females; mean age 14.2 ± 1.2 years; 12–18 years old) was included in the study. The measurements obtained by the 3D-TMT cephalometric analysis with a conventional frontal cephalometric analysis were compared for each subject. Nine passive markers reflectors were positioned on the face skin for the detection of the profile of the patient. Through the acquisition of these points, corresponding plans for three-dimensional posterior-anterior cephalometric analysis were found. Results. The cephalometric results carried out with 3D-TMT and with traditional posterior-anterior cephalometric analysis showed the 3D-TMT system values are slightly higher than the values measured on radiographs but statistically significant; nevertheless their correlation is very high. Conclusion. The recorded values obtained using the 3D-TMT analysis were correlated to cephalometric analysis, with small but statistically significant differences. The Dahlberg errors resulted to be always lower than the mean difference between the 2D and 3D measurements. A clinician should use, during the clinical monitoring of a patient, always the same method, to avoid comparing different millimeter magnitudes.

Are Three-Dimensional Monitors More Appropriate Than Two-Dimensional Monitors in the Three-Dimensional Analysis?

In orthognathic surgery, three-dimensional (3D) program-based analysis of 3D reconstructions of computed tomography (CT) images is commonly used, and images viewed on a monitor. The authors compared the coordinates of facial landmarks on images in a 3D program displayed on a two-dimensional (2D) (standard) or 3D monitor. Facial bone CT data from 30 patients were reconstructed in 3D. Four researchers identified 33 facial landmarks, 3 times each on 2D and 3D monitors, for each patient, by their x-, y-, and z-coordinates. The time taken to complete these identifications was measured.For each set of coordinates, the average intraclass coefficient was >0.8 for 2D and 3D analyses, as well as among 4 readers. It took on average of 2 minutes 46 seconds to identify the landmarks on the 2D monitor, compared with 2 minutes 25 seconds on the 3D monitor. The variance of individual coordinates differed when measured on 2D or 3D monitor. The landmarks affected were located near the median region of the facial area, and are important for setting the reference sagittal plane during diagnosis for orthognathic surgery. Therefore, identifying facial landmarks using 3D monitors may be helpful for conducting accurate facial diagnoses.