Validation and reproducibility of a high-resolution three-dimensional facial imaging system

Changes in three-dimensional nasal morphology according to the direction of maxillary movement during Le Fort I osteotomy

BACKGROUND

Le Fort I (LFI) osteotomy is commonly performed by orthognathic surgeons; however, postoperative changes in nasolabial morphology are of concern. Several factors influence such changes, but it is difficult to accurately predict the postoperative results. This study evaluated the three-dimensional (3D) morphological changes in the nasal region according to the different directions of maxillary movement during LFI osteotomy.

MATERIALS AND METHODS

Forty-one patients who underwent LFI osteotomies were included. All patients were divided into maxilla-up (Group U: 20 patients) and maxilla-forward (Group F: 21 patients) groups. Soft tissue morphologies were determined preoperatively and 3 or 6 months postoperatively using an optical 3D scanner. All datasets were evaluated in terms of volume changes in nine subregions and changes in linear measurements around the nasal area.

RESULTS

Both groups exhibited increased nasal volumes after surgery in the order of the three upper, three central, and three lower subregions. The change in volume of the central nasal region tended to be greater in Group U than that in Group F.

CONCLUSION

We evaluated 3D morphological changes in the nasal region according to the direction of maxillary movement during LFI osteotomy. Group U exhibited a large change in the volume of the central nasal 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 .

Frontiers in Three-Dimensional Surface Imaging Systems for 3D Face Acquisition in Craniofacial Research and Practice: An Updated Literature Review

Digitalizing all aspects of dental care is a contemporary approach to ensuring the best possible clinical outcomes. Ongoing advancements in 3D face acquisition have been driven by continuous research on craniofacial structures and treatment effects. An array of 3D surface-imaging systems are currently available for generating photorealistic 3D facial images. However, choosing a purpose-specific system is challenging for clinicians due to variations in accuracy, reliability, resolution, and portability. Therefore, this review aims to provide clinicians and researchers with an overview of currently used or potential 3D surface imaging technologies and systems for 3D face acquisition in craniofacial research and daily practice. Through a comprehensive literature search, 71 articles meeting the inclusion criteria were included in the qualitative analysis, investigating the hardware, software, and operational aspects of these systems. The review offers updated information on 3D surface imaging technologies and systems to guide clinicians in selecting an optimal 3D face acquisition system. While some of these systems have already been implemented in clinical settings, others hold promise. Furthermore, driven by technological advances, novel devices will become cost-effective and portable, and will also enable accurate quantitative assessments, rapid treatment simulations, and improved outcomes.

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion

OBJECTIVES

This study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy.

MATERIALS AND METHODS

Patients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect.

RESULTS

A total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0-T1 (p = 0.02), T0-T2 (p = 0.03), and T0-T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group.

CONCLUSIONS

We found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback.

CLINICAL RELEVANCE

It is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Accuracy of 3D facial scans: a comparison of three different scanning system in an in vivo study

BACKGROUND

The aim of the study was to compare the accuracy and reproducibility of three different 3D facial scanning systems, relying, respectively, on stereophotogrammetry, structured light and a smartphone app and camera.

METHODS

Thirty subjects have been scanned with three different facial scanning systems, stereophotogrammetry, structured light and a smartphone app and camera. Linear measurements were compared with direct anthropometries measured on the patient's face, while the study of areas (forehead, tip of the nose, chin, right and left cheek) was evaluated by overlapping scans using the Geomagic Control X program. Statistical analyses were conducted using IBM SPSS v28 software.

RESULTS

The ANOVA test was used to compare linear distances and direct anthropometry measurements, revealing statically significant values for all distances investigated, especially for the Face Hunter scanner, except for the Prn-Pog' distance (p = 0.092). The three facial scans were superimposed pairwise almost the 100 per cent of the overlapping areas fell within the tolerance limits for all three comparisons analysed. The chin was the most accurately reproduced, with no differences among scanners, while the forehead proved to be the least accurately reproduced by all scanners.

CONCLUSIONS

All three acquisition systems proved to be effective in capturing 3D images of the face, with the exception of the Face Hunter scanner, that produced statistically significant differences in linear measurements for the distances Tr-Na' and Zyg-Zyg with respect to direct anthropometric measurements.

Assessment of the reproducibility and accuracy of the Visia® Complexion Analysis Camera System for objective skin analysis of facial wrinkles and skin age

Objective

This study aimed to investigate the reproducibility and accuracy of the Visia® Complexion Analysis Camera System by Canfield Scientific for objective skin analysis.

Methods

Nineteen participants underwent facial capture with the Visia® camera following a standardised protocol. During the first session, the participants sat down and positioned their faces in a capture rig, closed their eyes and had their faces captured from the left, front and right sides, with threefold repetition of the captures from the front side. After 4 weeks, the participants underwent recapture in a similar manner. Based on the frontal views, data for two measurement methods of the Visia® camera system, the absolute scores and the percentiles, were obtained with regard to the skin criterion wrinkles via automated software calculation. Means and standard deviations were evaluated. Based on the side views, the data for the Truskin Ages® were calculated by the Visia® camera system and compared with the calendrical ages, which served as the gold standard for comparison.

Results

In the assessment of the reproducibility of the data of the capture system the standard deviation from the frontal captures among all participants was about 3% when the absolute scores of the wrinkles were compared with each other; specifically, the average deviation was 3.36% during the first capture session and 3.4% during the second capture session. Meanwhile, the standard deviation of the measurements was about 9% when the percentiles were compared; specifically, the average deviation was 8.2% during the first capture session and 10.7% during the second capture session. In the assessment of the accuracy the correlation between the calendrical age and the calculated Truskin Age® for both facial sides was very high at a correlation coefficient rho value of >0.8 (right side: r=0.896; left side: r=0.827) and statistically significant at a p-value of <0.001. The average calendrical age and Truskin Age® deviated only slightly from each other and did not differ significantly (right side: p=0.174; left side: p=0.190). The Truskin Age® was slightly higher than the calendrical age by a mean value of 1.37 years for both facial sides. The analysis of the absolute differences revealed that in 50% of the cases, there was a maximum difference of 3 years, and in 75% of the cases, there were maximum differences of 4.5 years for the right side and 5.5 years for the left side.

Conclusion

The assessment of the reproducibility and accuracy of the objective measurement method, the Visia® camera system, contributed to the validation of the system. The evaluation of the reproducibility revealed a satisfactory precision of the repeated captures when investigating facial wrinkles. Absolute scores should be preferred over percentiles owing to their better precision. The calculation of the accuracy of the Truskin Age® data from the Visia® camera system revealed only a slight deviation from the true calendrical ages. The correlation between both data groups was highly significant.

Accuracy (trueness and precision) of four tablet-based applications for three-dimensional facial scanning: an in-vitro study.: Tablet-based applications for 3D facial scanning

OBJECTIVES

This study aimed to investigate the overall and regional accuracy (trueness and precision) of digital three-dimensional (3D) facial scans obtained from four tablet-based applications, which were (Bellus) the Bellus Dental Pro® (Bellus3D, Inc. Campbell, CA, USA), (Capture) the Capture®: 3D Scan Anything (Standard Cyborg, Inc. San Francisco, CA, USA), (Heges) the Heges® (by Marek Simonik, Ostrava, North Moravia, Czech Republic), and (Scandy) the Scandy Pro 3D Scanner® (Scandy LLC, New Orleans, LA, USA).

METHODS

A mannequin's face was marked with 63 landmarks. Subsequently, it was scanned 5 times using each scan application on an iPad Pro® (Apple Inc., Cupertino, CA, USA). The digital measurements were obtained with MeshLab® (CNR-ISTI, Pisa, Tuscany, Italy) and compared to the manual measurements using a digital vernier caliper (Truper Herramientas S.A., Colonia Granada, Mexico City, Mexico). The absolute mean difference and the standard deviation of the dimensional discrepancies were calculated. Moreover, the data were analysed by using one-way ANOVA, Levene's test, and Bonferroni´s correction.

RESULTS

The absolute mean trueness values were Bellus 0.41 ± 0.35 mm, Capture 0.38 ± 0.37 mm, Heges 0.39 ± 0.38 mm, and Scandy 0.47 ± 0.44 mm. Moreover, precision values were Bellus 0.46 mm, Capture 0.46 mm, Heges 0.54 mm, and Scandy 0.64 mm. Comparing the regions, Capture and Scandy showed the highest absolute mean difference, which was 0.81 mm in the Frontal and Zygomaticofacial regions, respectively.

CONCLUSIONS

The trueness and precision of all four tablet-based applications were clinically acceptable for diagnosis and treatment planning.

CLINICAL SIGNIFICANCE

The future of the three-dimensional facial scan is auspicious, and it has the potential to be affordable, accurate, and of great value for clinicians in their daily practice.

Validation of three-dimensional facial imaging captured with smartphone-based photogrammetry application in comparison to stereophotogrammetry system

Statement of problem

The development of facial scanners has improved capabilities to create three-dimensional (3D) virtual patients for accurate facial and smile analysis. However, most of these scanners are expensive, stationary and involve a significant clinical footprint. The use of the Apple iPhone and its integrated "TrueDepth" near-infrared (NIR) scanner combined with an image processing application (app) offers the potential to capture and analyze the unique 3D nature of the face; the accuracy and reliability of which are yet to be established for use in clinical dentistry.

Purpose

This study was designed to validate both the trueness and precision of the iPhone 11 Pro smartphone TrueDepth NIR scanner in conjunction with the Bellus3D Face app in capturing 3D facial images in a sample of adult participants in comparison to the conventional 3dMDface stereophotogrammetry system.

Material and methods

Twenty-nine adult participants were prospectively recruited. Eighteen soft tissue landmarks were marked on each participant's face before imaging. 3D facial images were captured using a 3dMDface system and the Apple iPhone TrueDepth NIR scanner combined with the Bellus3D Face app respectively. The best fit of each experimental model to the 3dMD scan was analyzed using Geomagic Control X software. The root mean square (RMS) was used to measure the "trueness" as the absolute deviation of each TrueDepth scan from the reference 3dMD image. Individual facial landmark deviations were also assessed to evaluate the reliability in different craniofacial regions. The "precision" of the smartphone was tested by taking 10 consecutive scans of the same subject and comparing those to the reference scan. Intra-observer and inter-observer reliabilities were assessed using the intra-class correlation coefficient (ICC).

Results

Relative to the 3dMDface system, the mean RMS difference of the iPhone/Bellus3D app was 0.86 ± 0.31 mm. 97% of all the landmarks were within 2 mm of error compared with the reference data. The ICC for intra-observer reproducibility or precision of the iPhone/Bellus3D app was 0.96, which was classified as excellent. The ICC for inter-observer reliability was 0.84, which was classified as good.

Conclusions

These results suggest that 3D facial images acquired with this system, the iPhone TrueDepth NIR camera in conjunction with the Bellus3D Face app, are clinically accurate and reliable. Judicious use is advised in clinical situations that require high degrees of detail due to a lack of image resolution and a longer acquisition time. Generally, this system possesses the potential to serve as a practical alternative to conventional stereophotogrammetry systems for use in a clinical setting due to its accessibility and relative ease of use and further research is planned to appraise its updated clinical use.

Asymmetry index for the photogrammetric assessment of facial asymmetry

INTRODUCTION

Facial asymmetry is common and can be clinically related to dental malocclusion, facial bone development, muscular imbalance, and soft tissues thickness, which should be assessed during diagnosis to choose proper treatment options. This study aimed to quantify the amount of symmetry/asymmetry in previously defined symmetrical and asymmetrical subjects, analyzing full-face 3-dimensional images.

METHODS

Seventy-six orthodontic patients' 3-dimensional face images were obtained with the 3dMD Trio-system (Atlanta, Ga) and processed with the Geomagic Control (64-bit; 3D Systems, Rock Hill, SC) software. Patients were divided into symmetrical and asymmetrical groups through a surface-based technique. Sixteen facial landmarks were positioned, an asymmetry index was calculated for each landmark, and an evaluation diagram of facial asymmetry was created through the asymmetry index mean and standard deviation of symmetrical and asymmetrical landmarks.

RESULTS

The asymmetry index mean varied from 0.05 to 1.51 in the symmetrical group and from 0.05 to 2.84 in the asymmetrical group. This study suggests that landmarks located in the lower third of the face have a greater asymmetry index than other landmarks.

CONCLUSIONS

The landmark-based technique does not exhibit statistically significant differences among asymmetrical and symmetrical patients for some landmarks. This approach provides useful information about the localization and the extension of asymmetry, in which bilateral landmarks showed a higher amount of asymmetry than median landmarks.

3D Facial Analysis in Class II Subdivision Malocclusion

Background:

Class II subdivision is an asymmetric condition presenting a Class I dental occlusion on one side and a Class II on the contralateral one. It presents a midline deviation that may be caused by a monolateral distalization of the mandible (type 1) or a mesialization of one side of the maxilla (type 2). The evaluation of asymmetry based on 2D radiographic records has been demonstrated to be less accurate than the one made using 3D radiographs.

Objective:

The aim of this work is to evaluate the facial asymmetry in a group of patients with Class II subdivision, compared to patients in Class I without evident asymmetry, by using 3D photographs of the face.

Methods:

32 young adults with Class II subdivision were compared to a group of 32 subjects with bilateral Class I molar relationship. 3D photograph of their face was acquired using a stereophotogrammetric camera (3dMDtrio System-3dMD Atlanta, GA, USA). 3D photographs were imported into the Geomagic Software to create mirror 3D photography. Independent T-tests were made to compare facial asymmetries measured on Class II subdivision group with the Class I group.

Results:

The results show that there is a statistically significant difference in landmarks location between the control group and the experimental group regarding the values measured at the level of the lips and the perioral area. The asymmetry was more marked in patients with mandibular midline deviation. This is in line with previous observations with radiographic investigations.

Conclusion:

For a correct assessment of the asymmetry, a study of 3D photographs cannot replace an evaluation by cone beam, but it can be an important aid to estimate possible asymmetries in the perioral area and in the lip area.

Reproducibility of Novel Soft-Tissue Landmarks on Three-Dimensional Human Facial Scan Images in Caucasian and Asian

Background

Three-dimensional surface imaging is established in many disciplines for objective facial acquisition regarding anthropometry. Former studies addressed the validation of landmark-based measurements for single race. In order to distinguish racial difference, the reproducibility of the landmark measurements must first be validated.

Objectives

Our purpose is to validate the reproducibility of 46 facial soft-tissue landmarks on x, y, z axes to prove their reliability as 3D reference points.

Methods

The study included 80 European Caucasian and 80 Chinese volunteers. Standardized 3D surface imaging was performed using Vectra 3D system. Two raters identified and defined 46 landmarks (138 coordinates), then repeatedly 3D-imaged volunteers' facial region in separate sessions. Coordinates' reproducibility of landmarks is divided into three categories (< 0.5 mm, < 1 mm, and >1 mm) for intra- and inter-rater reproducibility assessments.

Results

Coordinates' reproducibility of 160 samples was distributed as follows: Intra-rater: < 0.5 mm (45%), < 1 mm (42%), >1 mm (13%); inter-rater: < 0.5 mm (31.2%), < 1 mm (42%), > 1 mm (26.8%). The reproducibility of landmarks in nasal tip region differs slightly between Caucasians and Asians. Compared to females, males typically have higher landmark reproducibility in lip and chin region. However, there were no differences in the reproducibility ranking of landmarks by gender.

Conclusion

The majority of the 46 landmarks in the 3D plane are reproducible to 1 mm, which is clinically acceptable. All selected landmarks showed strong consistency across race and gender, suggesting their potential use as reference points in prospective clinical practice.

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.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00266-021-02642-4.

A comparison between stereophotogrammetry and smartphone structured light technology for three-dimensional face scanning

OBJECTIVES

To compare three-dimensional facial scans obtained by stereophotogrammetry with two different applications for smartphone supporting the TrueDepth system, a structured light technology.

MATERIALS AND METHODS

Facial scans of 40 different subjects were acquired with three different systems. The 3dMDtrio Stereophotogrammetry System (3dMD, Atlanta, Ga) was compared with a smartphone (iPhone Xs; Apple, Cupertino, Calif) equipped with the Bellus3D Face Application (version 1.6.11; Bellus3D Inc, Campbell, Calif) or Capture (version 1.2.5; Standard Cyborg Inc, San Francisco, Calif). Times of image acquisition and elaboration were recorded. The surface-to-surface deviation and the distance between 18 landmarks from 3dMD reference images to those acquired with Bellus3D or Capture were measured.

RESULTS

Capturing and processing times with the smartphone applications were considerably longer than with the 3dMD system. The surface-to-surface deviation analysis between the Bellus3D and 3dMD showed an overlap percentage of 80.01% ± 5.92% and 56.62% ± 7.65% within the ranges of 1 mm and 0.5 mm discrepancy, respectively. Images from Capture showed an overlap percentage of 81.40% ± 9.59% and 56.45% ± 11.62% within the ranges of 1 mm and 0.5 mm, respectively.

CONCLUSIONS

The face image acquisition with the 3dMD device is fast and accurate, but bulky and expensive. The new smartphone applications combined with the TrueDepth sensors show promising results. They need more accuracy from the operator and more compliance from the patient because of the increased acquisition time. Their greatest advantages are related to cost and portability.

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).

Morphometry and displacement analysis of the upper lips following maxillary full-arch implant-supported fixed prostheses: a 3D morphometric study

BACKGROUND

With the emergence of three-dimensional (3D) integration technology, analysis of soft tissue displacement and morphological changes after maxillary full-arch implant-supported fixed prostheses can be performed. The aim of this study was to verify the feasibility of the 3D integration method for constructing the relative position of the prostheses and facial soft tissue, evaluate the displacement and morphological variation of the upper lips after maxillary full-arch implant-supported fixed prostheses.

METHODS

Twenty-five maxillary edentulous patients were recruited in this study. At the time of final prosthesis delivery, the 3D prostheses data and three 3D facial profiles were integrated. After method validation, the 3D position changes of seven soft tissue landmarks were used to reflect the 25 upper lips. The variation of four morphological distances were analyzed to reflect the morphological alteration of the upper lips. Two pairs of dentofacial landmarks were used to analyze the sagittal relative position of the prostheses and soft tissue. The included patients were also grouped to determine the impact of sex, upper lip thickness, and length on lip support changes.

RESULTS

The average distance of the two matched relative reliable forehead regions was only 0.32 mm. The sagittal shifts of labrale superius (LS), stomion (STO), crista philtri left (CPHL) and crista philtri right (CPHR) were 3.44 ± 1.39 mm, 2.52 ± 1.38 mm, 3.04 ± 1.18 mm, and 3.12 ± 1.21 mm, respectively. With the exception of the decrease in the length of subnasale (SN)-LS, the length of cheilion right (CHR)-cheilion left (CHL), CPHR-CPHL, and LS-STO significantly increased. The two pairs of dentofacial landmarks had strong positive movement correlations along the sagittal direction. Patients with thinner and longer lips showed more lip support than those with thicker and shorter lips by a clinically insignificant amount.

CONCLUSIONS

The integration method of 3D facial and dental data showed high repeatability in constructing the dentofacial relative position. The linear equations reflecting dentofacial relative position could aid clinicians in evaluating the restoration effect and estimate the upper lip variation.

Anthropometric accuracy of three-dimensional average faces compared to conventional facial measurements

This study aimed to evaluate and compare the accuracy of average faces constructed by different methods. Original three-dimensional facial images of 26 adults in Chinese ethnicity were imported into Di3DView and MorphAnalyser for image processing. Six average faces (Ave_D15, Ave_D24, Ave_MG15, Ave_MG24, Ave_MO15, Ave_MO24) were constructed using "surface-based registration" method with different number of landmarks and template meshes. Topographic analysis was performed, and the accuracy of six average faces was assessed by linear and angular parameters in correspondence with arithmetic means calculated from individual original images. Among the six average faces constructed by the two systems, Ave_MG15 had the highest accuracy in comparison with the conventional method, while Ave_D15 had the least accuracy. Other average faces were comparable regarding the number of discrepant parameters with clinical significance. However, marginal and non-registered areas were the most inaccurate regions using Di3DView. For MorphAnalyser, the type of template mesh had an effect on the accuracy of the final 3D average face, but additional landmarks did not improve the accuracy. This study highlights the importance of validating software packages and determining the degree of accuracy, as well as the variables which may affect the result.

Three-dimensional soft tissue changes in orthodontic extraction and non-extraction patients: A prospective study

OBJECTIVES

To assess the soft tissue changes in orthodontic extraction and non-extraction patients on 3D stereophotogrammetric images.

SETTING AND SAMPLE

23 extraction (22.2 ± 9.2 years) and 23 non-extraction (20.3 ± 11.1 years) consecutive patients were enrolled at the Sections of Orthodontics at Aarhus University and at University of Naples Federico II.

METHODS

All patients had a first 3D image taken after bonding of brackets on the upper incisors (T0), and a second 3D image (T1) after space closure in the extraction group or at insertion of the first SS or TMA rectangular wire in the non-extraction group. The 3D images were captured with 3dMDFace System and analysed with 3dMDVultus Software. After placing 19 landmarks, 15 measurements were obtained. Intragroup changes were analysed with paired t-test and intergroup changes with unpaired t-test (P < .05).

RESULTS

Superimpositions of the 3D images at T0 and T1 visualized with colour-coded maps showed that soft tissue changes primarily happened in the perioral area in both groups. The Nasolabial angle increased significantly in the extraction group (3°± 4.1, P = .002), while it decreased in the non-extraction group (-1.5°± 5.5°, P = .002). There was a significant difference between the two groups (4.4°, P = .004).

CONCLUSIONS

3D comparison of the soft tissues in the extraction and non-extraction groups showed statistically significant, but clinically limited differences in the perioral area. The Nasolabial angle was significantly larger at T1 in the extraction group compared with the non-extraction group.

Accuracy and Reliability of Kinect Motion Sensing Input Device’s 3D Models: A Comparison to Direct Anthropometry and 2D Photogrammetry

AIM: This study aims to evaluate the accuracy and reliability of Kinect motion sensing input device’s three-dimensional (3D) models by comparing it with direct anthropometry and digital 2D photogrammetry. MATERIALS AND METHODS: Six profiles and four frontal parameters were directly measured on the faces of 80 participants. The same measurements were repeated using two-dimensional (2D) photogrammetry and (3D) images obtained from Kinect device. Another observer made the same measurements for 30% of the images obtained with 3D technique, and interobserver reproducibility was evaluated for 3D images. Intraobserver reproducibility was evaluated. Statistical analysis was conducted using the paired samples t-test, interclass correlation coefficient, and Bland-Altman limits of agreement. RESULTS: The highest mean difference was 0.0084 mm between direct measurement and photogrammetry, 0.027 mm between direct measurement and 3D Kinect’s models, and 0.018 mm between photogrammetry and 3D Kinect’s. The lowest agreement value was 0.016 in the all parameter between the photogrammetry and 3D Kinect’s methods. Agreement between the two observers varied from 0.999 Sn-Me to 1 with the rest of linear measurements. CONCLUSION: Measurements done using 3D Images obtained from Kinect device indicate that it may be an accurate and reliable imaging method for use in orthodontics. It also provides an easy low-cost 3D imaging technique that has become increasingly popular in clinical settings, offering advantages for surgical planning and outcome evaluation.

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.

New aspects in digital breast assessment: further refinement of a method for automated digital anthropometry

Purpose

In this trial, we used a previously developed prototype software to assess aesthetic results after reconstructive surgery for congenital breast asymmetry using automated anthropometry. To prove the consensus between the manual and automatic digital measurements, we evaluated the software by comparing the manual and automatic measurements of 46 breasts.

Methods

Twenty-three patients who underwent reconstructive surgery for congenital breast asymmetry at our institution were examined and underwent 3D surface imaging. Per patient, 14 manual and 14 computer-based anthropometric measurements were obtained according to a standardized protocol. Manual and automatic measurements, as well as the previously proposed Symmetry Index (SI), were compared.

Results

The Wilcoxon signed-rank test revealed no significant differences in six of the seven measurements between the automatic and manual assessments. The SI showed robust agreement between the automatic and manual methods.

Conclusion

The present trial validates our method for digital anthropometry. Despite the discrepancy in one measurement, all remaining measurements, including the SI, showed high agreement between the manual and automatic methods. The proposed data bring us one step closer to the long-term goal of establishing robust instruments to evaluate the results of breast surgery.

Level of evidence: IV.

Modeling and measuring average nasal asymmetry by dorsum midline and nose tip lateral deviation

In rhinoplasty and nasal reconstruction, achieving symmetry is critical for optimal patient outcomes and reducing re-operation rates. Assessing nasal asymmetry is challenging, both pre- and intra-operatively, if based on only a surgeons' visual perception to assess and adjust the small distances important to cosmesis (<2-3 mm). To measure nasal symmetry, we first developed an algorithm to analyze lateral nasal deviation on facial three-dimensional (3D) scans captured by external surface scanning. In this, nasal deviation is measured by first registering a 3D facial scan to orthogonal axes in order to remove tilt. The lateral position of the nasal midline is then found across transverse planes along the dorsum and nasal tip regions by probing midpoints 1 and 2 mm back from the local maximum projection. The nasal deviation measurement algorithm was validated on a simulated asymmetrical nose model with known nasal deviation. Simulated deviations were applied to the symmetrical average nose using an exponential twist away from the face, with control of the maximum deviation and degree of curvature. Modeled deviations were evaluated with the algorithm at clinically negligible (0.02-0.06 mm) average differences and for small lateral deviations (1-5 mm). Nasal deviation using the algorithms was then measured for the 100 multi-ethnic subjects in the Binghamton University 3D Facial Expression database. Average values for maximum lateral deviation, deviation across the whole nose, and deviation at the nose tip were measured to provide context to deviation measurements in surgical planning. This research presents a new nasal assessment tool that can be useful in improving symmetry in rhinoplasty and reconstruction.

Three-dimensional facial capture using a custom-built photogrammetry setup: Design, performance, and cost

INTRODUCTION

Although stereophotogrammetry is increasingly popular for 3-dimensional face scanning, commercial solutions remain quite expensive, limiting its accessibility. We propose a more affordable, custom-built photogrammetry setup (Stereo-Face 3D, SF3D) and evaluate its variability within and between systems.

METHODS

Twenty-nine subjects and a mannequin head were imaged 3 times using SF3D and a commercially available system. An anthropometric mask was mapped viscoelastically onto the reconstructed meshes using MeshMonk (https://github.com/TheWebMonks/meshmonk). Within systems, shape variability was determined by calculating the root-mean-square error (RMSE) of the Procrustes distance between each of the subject's 3 scans and the subject's ground truth (calculated by averaging the mappings after a nonscaled generalized Procrustes superimposition). Intersystem variability was determined by similarly comparing the ground truth mappings of both systems. Two-factor Procrustes analysis of variance was used to partition the intersystem shape variability to understand the source of the discrepancies between the facial shapes acquired by both systems.

RESULTS

The RMSEs of the within-system shape variability for 3dMDFace and SF3D were 0.52 ± 0.07 mm and 0.44 ± 0.16 mm, respectively. The corresponding values for the mannequin head were 0.42 ± 0.02 mm and 0.29 ± 0.03 mm, respectively. The between-systems RMSE was 1.6 ± 0.34 mm for the study group and 1.38 mm for the mannequin head. A 2-factor analysis indicated that variability attributable to the system was expressed mainly at the upper eyelids, nasal tip and alae, and chin areas.

CONCLUSIONS

The variability values of the custom-built setup presented here were competitive to a state-of-the-art commercial system at a more affordable level of investment.

Reliability of optical devices for three-dimensional facial anatomy description: a systematic review and meta-analysis

The use of three-dimensional (3D) optical instruments to measure soft tissue facial characteristics is increasing, but systematic assessments of their reliability, practical use in research and clinics, outcome measurements, and advantages and limitations are not fully established. Therefore, a review of the current literature was performed on the reliability of facial anthropometric measurements obtained by 3D optical facial reproductions as compared to conventional anthropometry or other optical devices. The systematic literature search was conducted in electronic databases following the PRISMA guidelines (PROSPERO registration: CRD42018085473). Overall, 815 studies were identified, with 27 final papers included. Two meta-analyses were conducted. Tested devices included conventional cameras, laser scanning, stereophotogrammetry, and structured light. Studies measured living people or inanimate objects. Overall, the optical devices were considered reliable for the measurement of linear distances. Some caution is needed for surface assessments. All instruments are suitable for the analysis of inanimate objects, but fast scan devices should be preferred for living subjects to avoid motion artefacts in the orbital and nasolabial areas. Prior facial landmarking is suggested to improve measurement accuracy. Practical needs and economic means should direct the choice of the most appropriate instrument. Considering the increasing interest in surface-to-surface measurements, fast scan devices should be preferred, and dedicated protocols devised.

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.

Reliability of periocular anthropometry using three-dimensional digital stereophotogrammetry

PURPOSE

Non-invasive three-dimensional (3D) stereophotogrammetry is becoming increasingly popular in many fields. However, few studies have focused on its periocular application. We aimed to provide evidence for the periocular application of a novel anthropometric procedure using 3D stereophotogrammetry by evaluating its reliability.

METHODS

Fifty-one Caucasians were recruited (102 eyes; mean age, 31.9 ± 13.6 years). Two sets of 3D images were acquired for each subject, and two measurement sessions were performed on each image by two raters. Fifty-two periocular landmarks were identified, and then 49 corresponding linear, curvilinear, and angular measurements were evaluated for intrarater, interrater, and intramethod reliability.

RESULTS

Our findings showed highly reliable results for mean absolute difference (0.59 and 0.68 unit), relative error measurement (2.66% and 3.08%), technical error of measurement (0.59 and 0.66 unit), relative technical error of measurement (2.71% and 2.96%), and intraclass correlation coefficient (0.98) for intrarater 1 and intrarater 2 reliability; respectively 0.94 unit, 4.06%, 0.89 unit, and 3.94%, as well as 0.97 for interrater reliability; and respectively 0.98 unit, 4.66%, 0.96 unit, and 4.64%, as well as 0.96 for intramethod reliability.

CONCLUSIONS

This imaging system and the landmark identification protocol are highly reliable. The collected measurements and their errors can be applied for the comparison of reliability among various 3D imaging systems and populations. It could be utilized for planning surgeries and evaluating treatment outcomes for physicians in ophthalmology, plastic and esthetic surgery, and in the maxillofacial field where periocular morphology alterations are made.

Scan time, reliability and accuracy of craniofacial measurements using a 3D light scanner

Aim

To evaluate time, reliability and accuracy of craniofacial measurements with a 3D light scanner, considering prior demarcation of surface points on the face.

Materials and methods

Eleven facial measurements of 15 volunteers were obtained by a scanner (Artec Eva TM) and by a caliper directly on the face, with or without demarcation of facial reference points. Inter and intra-method comparison were examined by intraclass correlation coefficient and analysis of random error by the Dahlberg formula. Agreement between the methods was analyzed by the Bland-Altman. A Wilcoxon test was used to compare the time for each method, at p < 0.05.

Results

Marking points on the face improved accuracy for both methods. In the inter-methods analysis with landmarks, the scanner showed excellent reliability in all measures (ICC = 0.92-0.97, p < 0.0001). Measurements accuracy with scanner was around 2 mm when the points were not previously marked and about 1 mm when the points were marked. Measures taken with the scanner, however, took twice as long, compared with the direct method.

Conclusions

Craniofacial measurements obtained with scanner showed excellent reliability and accuracy, which qualifies this method for clinical and scientific use. Accuracy is improved when the points were previously marked on face. However, the time needed to obtain measurements is greater than about 4 min for the direct method.

An overview of the latest developments in facial imaging

Facial imaging is a term used to describe methods that use facial images to assist or facilitate human identification. This pertains to two craniofacial identification procedures that use skulls and faces-facial approximation and photographic superimposition-as well as face-only methods for age progression/regression, the construction of facial graphics from eyewitness memory (including composites and artistic sketches), facial depiction, face mapping and newly emerging methods of molecular photofitting. Given the breadth of these facial imaging techniques, it is not surprising that a broad array of subject-matter experts participate in and/or contribute to the formulation and implementation of these methods (including forensic odontologists, forensic artists, police officers, electrical engineers, anatomists, geneticists, medical image specialists, psychologists, computer graphic programmers and software developers). As they are concerned with the physical characteristics of humans, each of these facial imaging areas also falls in the domain of physical anthropology, although not all of them have been traditionally regarded as such. This too offers useful opportunities to adapt established methods in one domain to others more traditionally held to be disciplines within physical anthropology (e.g. facial approximation, craniofacial superimposition and face photo-comparison). It is important to note that most facial imaging methods are not currently used for identification but serve to assist authorities in narrowing or directing investigations such that other, more potent, methods of identification can be used (e.g. DNA). Few, if any, facial imaging approaches can be considered honed end-stage scientific methods, with major opportunities for physical anthropologists to make meaningful contributions. Some facial imaging methods have considerably stronger scientific underpinnings than others (e.g. facial approximation versus face mapping), some currently lie entirely within the artistic sphere (facial depiction), and yet others are so aspirational that realistic capacity to obtain their aims has strongly been questioned despite highly advanced technical approaches (molecular photofitting). All this makes for a broad-ranging, dynamic and energetic field that is in a constant state of flux. This manuscript provides a theoretical snapshot of the purposes of these methods, the state of science as it pertains to them, and their latest research developments.

Using three-dimensional average facial meshes to determine nasolabial soft tissue deformity in adult UCLP patients

BACKGROUND AND PURPOSE

There is limited literature discussing the residual nasolabial deformity of adult patients prior to undergoing orthognathic surgery. The purpose of this study is to determine the site and severity of the residual nasolabial soft tissue deformity between adult unilateral cleft lip and palate (UCLP) patients and a non-cleft reference group, prior to orthognathic surgery.

MATERIAL AND METHODS

Sixteen adult male UCLP patients, who all received primary lip and palate surgery according to a standardised Hong Kong protocol were recruited for this study. Facial images of each individual were captured using three-dimensional (3D) stereophotogrammetry and compared to a previous published Hong Kong non-cleft reference group of 48 male adults. Using two-sample t-tests differences in linear and angular measurements and asymmetry scores were evaluated between the two groups. In addition a "conformed" average UCLP facial template was superimposed and compared to conformed average non-cleft reference group facial template. Reproducibility of the measurements were assessed using Students paired t-tests and coefficients of reliability.

MAIN FINDINGS

Significant differences in linear and angular measurements and asymmetry scores were observed between the two groups (p < 0.05). Adult UCLP patients showed significantly narrower nostril floor widths, longer columella length on the unaffected side, a wider nose, shorter cutaneous lip height, shorter upper lip length and shorter philtrum length. Prior to orthognathic surgery adult UCLP patients showed significantly more facial asymmetry. Superimposition of the average facial meshes clearly showed the site and severity of the deficiency in the x, y and z-directions.

CONCLUSIONS

Many of the nasolabial characteristics reported to be present in children following primary UCLP repair continue into adulthood. The detrimental soft tissue effects of orthognathic surgery for UCLP patients may be different to non-cleft individuals; and as such the site and severity of the residual deformity should be assessed prior to surgery.

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.

Postoperative Edema Resolution following Rhinoplasty: A Three-Dimensional Morphometric Assessment

BACKGROUND

The final result of rhinoplasty may be masked for several months after surgery because of postoperative edema; however, no objective evidence supports this time estimate. The purpose of this study was to three-dimensionally quantify the decrease in postsurgical nasal edema following rhinoplasty over the first postoperative year.

METHODS

This was a retrospective, three-dimensional, morphometric study of primary, open rhinoplasty patients. Subjects with at least three postoperative three-dimensional images up to 1 year were included. Patients were excluded for closed or secondary procedures or cleft deformities. Images were assessed using three-dimensional stereophotogrammetry (Vectra) and volumetric analysis (Geomagic). Baseline nasal volume (time 0) occurred at the first postoperative visit at 1 to 2 weeks. All subsequent nasal volume measurements were calculated as a percentage of baseline values. Data points from all patients were pooled, and a six-point moving average was used to create an inverse function line of best fit.

RESULTS

Forty patients were included, with 146 three-dimensional photographs quantified. The equation for the inverse function line of best fit of the six-point moving average was y = 1.484 (1/x) + 0.844 (R = 0.85, p < 0.01). According to this equation, approximately two-thirds of edema resolves within the first month, 95 percent after 6 months, and 97.5 percent after 1 year. A plateau is reached at 84.4 percent of the original postoperative volume.

CONCLUSIONS

This study provides quantitative evidence to predict decrement of rhinoplasty edema with time. Three-dimensional morphometric assessment demonstrated a two-thirds decrease in edema at 1 month, a 95 percent decrease at 6 months, and a 97.5 percent decrease at 1 year.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Influence of Connecting Two Standalone Mobile Three-Dimensional Scanners on Accuracy Comparing with a Standard Device in Facial Scanning

Objectives

In this study is investigated if bundling of two scanners leads to better accuracy in recording faces than a standard face-scanning device.

Material and Methods

In a group of 28 volunteers, two test specimens were attached to their faces: one on their forehead and one turned 90° on their cheek. Each volunteer was scanned by FaceScan3D^® and two bundled Artec EVA^® scanners. The scans were aligned to a three-dimensional model of the test specimen, and the mean error was recorded. Length, width and angles between the test specimen’s planes were compared.

Results

The mean deviation is significantly lower for the cheek test specimen in alignment (P < 0.001), length and width (P < 0.001) but not for the forehead test specimen in alignment and length and width (P > 0.05) using FaceScan3D^®. The aberration from the original angle between two sides of the test specimen is significantly lower measured with Artec EVA^® for the angle between the front and the bottom plane of both test specimens (P < 0.01). Besides the angle between the right plane and the bottom plane as well as the top plane of the test specimen mounted to the cheek, the deviation of the angle between the other side planes to each other is significantly lower (P > 0.05) scanned with Artec EVA^®.

Conclusions

Compared to FaceScan3D^®, two bundled Artec EVA^® scanners provide different accuracies depending on the location of the measured parameters. The accuracy measured for both scanners is inside the range found in the literature.

Evaluation of the accuracy of a mobile and a stationary system for three-dimensional facial scanning

PURPOSE

Numerous three-dimensional (3D) facial scanners have emerged on the market; however, publications evaluating their accuracies are sparse. In this study, the accuracy of two 3D scanners used in facial scanning was evaluated.

MATERIALS AND METHODS

A test specimen was attached at the right cheek and the forehead of 41 volunteers. These volunteers were scanned with Artec EVA^® and FaceScan3D^®. The acquired data were aligned to a 3D model of the test specimen for comparing the mean error, original length and width and angles to the measured values.

RESULTS

The mean error in Best Fit alignment is significantly lower using Artec EVA (p < 0.001) for both test specimens. The deviation from the original length and width is significantly lower for the test specimens (p < 0.01) when measured with Artec EVA. The aberration of the angles measured between the front plane and the side plane is significantly lower when measured with Artec EVA (p < 0.001). Captured with Artec EVA the discrepancy between the original angle and the angle measured between the side planes to each other is significantly lower (p < 0.01).

CONCLUSIONS

Scanning with Artec EVA leads to more accurate 3D models as compared to scanning with FaceScan3D. The exactness achieved by both scanners is comparable to other scanners mentioned in literature.

Single-pixel three-dimensional imaging with time-based depth resolution

Time-of-flight three-dimensional imaging is an important tool for applications such as object recognition and remote sensing. Conventional time-of-flight three-dimensional imaging systems frequently use a raster scanned laser to measure the range of each pixel in the scene sequentially. Here we show a modified time-of-flight three-dimensional imaging system, which can use compressed sensing techniques to reduce acquisition times, whilst distributing the optical illumination over the full field of view. Our system is based on a single-pixel camera using short-pulsed structured illumination and a high-speed photodiode, and is capable of reconstructing 128 × 128-pixel resolution three-dimensional scenes to an accuracy of ∼3 mm at a range of ∼5 m. Furthermore, by using a compressive sampling strategy, we demonstrate continuous real-time three-dimensional video with a frame-rate up to 12 Hz. The simplicity of the system hardware could enable low-cost three-dimensional imaging devices for precision ranging at wavelengths beyond the visible spectrum.

A three-dimensional imaging system which distributes the optical illumination over the full field-of-view is sought after. Here, the authors demonstrate the capability of reconstructing 128 × 128 pixel resolution three-dimensional scenes to an accuracy of 3 mm as well as real-time video with a frame-rate up to 12 Hz.

Breast volumetric analysis for aesthetic planning in breast reconstruction: a literature review of techniques

BACKGROUND

Accurate volumetric analysis is an essential component of preoperative planning in both reconstructive and aesthetic breast procedures towards achieving symmetrization and patient-satisfactory outcome. Numerous comparative studies and reviews of individual techniques have been reported. However, a unifying review of all techniques comparing their accuracy, reliability, and practicality has been lacking.

METHODS

A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE, was undertaken.

RESULTS

Since Bouman's first description of water displacement method, a range of volumetric assessment techniques have been described: thermoplastic casting, direct anthropomorphic measurement, two-dimensional (2D) imaging, and computed tomography (CT)/magnetic resonance imaging (MRI) scans. However, most have been unreliable, difficult to execute and demonstrate limited practicability. Introduction of 3D surface imaging has revolutionized the field due to its ease of use, fast speed, accuracy, and reliability. However, its widespread use has been limited by its high cost and lack of high level of evidence. Recent developments have unveiled the first web-based 3D surface imaging program, 4D imaging, and 3D printing.

CONCLUSIONS

Despite its importance, an accurate, reliable, and simple breast volumetric analysis tool has been elusive until the introduction of 3D surface imaging technology. However, its high cost has limited its wide usage. Novel adjunct technologies, such as web-based 3D surface imaging program, 4D imaging, and 3D printing, appear promising.

Evaluation of the Reproducibility of Nonverbal Facial Expressions Using a 3D Motion Capture System

Objective

To evaluate the reproducibility of three nonverbal facial expressions using a three-dimensional motion capture system.

Design

Prospective, cross-sectional, controlled study.

Setting

Glasgow Dental Hospital and School, University of Glasgow, United Kingdom.

Patients and Participants

Thirty-two subjects, 16 males and 16 females.

Methods

With a three-dimensional video passive stereophotogrammetry imaging system, maximal smile, cheek puff, and lip purse were captured for each subject. Anatomical facial landmarks were digitized on the first frame and then tracked automatically. The same facial expressions were captured 15 minutes later.

Main Outcome Measures

The magnitude of each expression and speed of landmark displacement were calculated. The landmark motion curves were spatially and temporally aligned to calculate the similarity of the dynamic movements of the same landmarks between the captures.

Results

There were no significant differences between individuals for magnitude ( P = .892) or for speed ( P = .456). There were significant differences in landmark movement similarity ( P = .011); similarity was more reproducible for maximal smile. There was no significant gender effect on the difference in magnitude. There was a significant gender effect on speed to reach maximal smile ( P = .044) and a pursed-lip expression ( P = .038). There was a significant gender effect on landmark movement similarities ( P = .031) for cheek puff expression.

Conclusions

There were no differences in magnitude and speed for maximal smile, cheek puff, and lip purse between the two captures for all participants. For individual expressions, maximal smile expression had the highest similarity value for individual landmarks.

Three-dimensional cephalometric analysis of adolescents with cleft lip and palate using computed tomography-guided imaging

OBJECTIVE

To propose landmarks and a new coordinate system to aid three-dimensional cephalometric analysis of adolescent cleft lip and palate (CLP) using computed tomography (CT) imaging.

METHODS

Sixty-four-row CT images obtained from 52 adolescent patients were retrospectively analyzed with the MIMICS program (MIMICS 10.02; Materialise Technologies, Leuven, Belgium) to determine intrarater reliability of new landmarks for three-dimensional cephalometric analysis before surgery.

RESULTS

Five points were located on each image including the midpoint between both uppermost external points of the external auditory meatus (EAM), the center of the sella turcica (sella, S), the most anterior point on the nasofrontal suture in the midline (nasion, N), and the right and left lowest points of the lower edge of the orbitale (r/l orbitale, r/l Or). The horizontal reference plane was then determined using EAM and bilateral Or. The sagittal reference plane was defined perpendicular to the horizontal plane, passing through N and S. The coronal reference plane included the EAM landmark and was perpendicular to the sagittal and horizontal planes. All 5 points had high intrarater reliability and proved easy to use in constructing the new coordinate system. The horizontal, sagittal, and coronal reference planes formed by these respective points improved the ease of performing three-dimensional cephalometric analysis of CLP adolescents with CT imaging.

CONCLUSIONS

Our 5 landmarks provided reliable CT-guided three-dimensional cephalometric analysis of CLP, allowing for accurate quantitative assessment in adolescents before orthognathic surgery.

Comparative Accuracy of Facial Models Fabricated Using Traditional and 3D Imaging Techniques

PURPOSE

The purpose of this investigation was to compare the accuracy of facial models fabricated using facial moulage impression methods to the three-dimensional printed (3DP) fabrication methods using soft tissue images obtained from cone beam computed tomography (CBCT) and 3D stereophotogrammetry (3D-SPG) scans.

MATERIALS AND METHODS

A reference phantom model was fabricated using a 3D-SPG image of a human control form with ten fiducial markers placed on common anthropometric landmarks. This image was converted into the investigation control phantom model (CPM) using 3DP methods. The CPM was attached to a camera tripod for ease of image capture. Three CBCT and three 3D-SPG images of the CPM were captured. The DICOM and STL files from the three 3dMD and three CBCT were imported to the 3DP, and six testing models were made. Reversible hydrocolloid and dental stone were used to make three facial moulages of the CPM, and the impressions/casts were poured in type IV gypsum dental stone. A coordinate measuring machine (CMM) was used to measure the distances between each of the ten fiducial markers. Each measurement was made using one point as a static reference to the other nine points. The same measuring procedures were accomplished on all specimens. All measurements were compared between specimens and the control. The data were analyzed using ANOVA and Tukey pairwise comparison of the raters, methods, and fiducial markers.

RESULTS

The ANOVA multiple comparisons showed significant difference among the three methods (p < 0.05). Further, the interaction of methods versus fiducial markers also showed significant difference (p < 0.05). The CBCT and facial moulage method showed the greatest accuracy.

CONCLUSIONS

3DP models fabricated using 3D-SPG showed statistical difference in comparison to the models fabricated using the traditional method of facial moulage and 3DP models fabricated from CBCT imaging. 3DP models fabricated using 3D-SPG were less accurate than the CPM and models fabricated using facial moulage and CBCT imaging techniques.

Accuracy and reliability of 3D stereophotogrammetry: A comparison to direct anthropometry and 2D photogrammetry

OBJECTIVE

To evaluate the accuracy of three-dimensional (3D) stereophotogrammetry by comparing it with the direct anthropometry and digital photogrammetry methods. The reliability of 3D stereophotogrammetry was also examined.

MATERIALS AND METHODS

Six profile and four frontal parameters were directly measured on the faces of 80 participants. The same measurements were repeated using two-dimensional (2D) photogrammetry and 3D stereophotogrammetry (3dMDflex System, 3dMD, Atlanta, Ga) to obtain images of the subjects. Another observer made the same measurements for images obtained with 3D stereophotogrammetry, and interobserver reproducibility was evaluated for 3D images. Both observers remeasured the 3D images 1 month later, and intraobserver reproducibility was evaluated. Statistical analysis was conducted using the paired samples t-test, intraclass correlation coefficient, and Bland-Altman limits of agreement.

RESULTS

The highest mean difference was 0.30 mm between direct measurement and photogrammetry, 0.21 mm between direct measurement and 3D stereophotogrammetry, and 0.5 mm between photogrammetry and 3D stereophotogrammetry. The lowest agreement value was 0.965 in the Sn-Pro parameter between the photogrammetry and 3D stereophotogrammetry methods. Agreement between the two observers varied from 0.90 (Ch-Ch) to 0.99 (Sn-Me) in linear measurements. For intraobserver agreement, the highest difference between means was 0.33 for observer 1 and 1.42 mm for observer 2.

CONCLUSIONS

Measurements obtained using 3D stereophotogrammetry indicate that it may be an accurate and reliable imaging method for use in orthodontics.

3D stereophotogrammetry facial analysis of Angle I subjects: gender comparison

Objective The aim of this study was to establish reference parameters for facial analysis in subjects with Angle’s Class I occlusion by means of stereophotogrammetry, comparing men and women. Material and method Twenty-six healthy young adults with Angle’s Class I occlusion volunteered to participate in the study, 15 males and 11 females, ages between 18 and 30 years old (22 years ± 5). These subjects were clinically examined to verify their type of occlusion. Twenty-five landmarks were performed in soft tissue, and those subjects underwent image capturing by the stereophotogrammetry technique, using the apparatus Vectra (M3-Canfield®). The following variables were measured in those images: naso-labial angle (C-Sn-Ls); (N-Prn-Pg); (N-Sn-Pg); mentolabial (Li-Ps-Pg); growth angle (T-Go-Pg), cheek area (T, Zy, Chk, Ch, Gn, Go), hemifaces' areas (T, Zy, Ft, Tr, N, Prn, C, Sn, Ls, Sto, Li Ps, Gn, Go), lip area, bilaterally (Ls, Cph, Ch, Li, Sto), and linear measurements of the lips and jaw. Result and conclusion The data were compared between genders (Student's t-test), and no statistically significant differences between groups (p>0.05) were found. Despite the limitations of this study, it is possible to conclude that, as there were no differences between men and women for the studied variables (angular, linear, and area), the data of the total sample (Class I) should be used as reference parameters in future studies. Additionally, the 3D stereophotogrammetry technique has proven to be a new possibility for facial analysis, which might be employed in several areas of dentistry.

Immediate effects of rapid maxillary expansion on the naso-maxillary facial soft tissue using 3D stereophotogrammetry

BACKGROUND

Rapid maxillary expansion (RME) is used to expand the narrow maxilla. Dental and skeletal affects have previously been reported but few studies have reported on the overlying soft tissue changes. This study reports on the immediate effects of RME on the naso-maxillary facial soft tissue using 3D stereophotogrammetry.

METHODS

Fourteen patients requiring upper arch expansion using RME as part of their full comprehensive orthodontic plan were recruited. Cone beam CT scans and stereophotogrammetry images were taken for each patient; pre-RME activation (T0) and immediately post-RME expansion (T1). Based on twenty-three landmarks, 13 linear and 3 angular measurements were made from each of the stereophotogrammetry images. A linear measurement at ANS was taken from each CBCT image. Using a Wilcoxon signed rank test, the pre-RME and post-RME measurements were compared.

RESULTS

The mean separation of the anterior nasal spine was 3.8 mm ± 1.2 mm. The largest median increase was in nasal base width (1.6 mm), which was statistically significant (p = 0.001). Changes in the nasal dorsum height, nasal tip protrusion, philtrum width, and upper lip length were not statistically significant (p < 0.05). No significant differences were observed in the nostril linear measurements, expect for columella width (p = 0.009). Naso-labial angle decreased but was not statistically significant (p = 0.276). The only statically significant angular change was an increase in the nasal tip displacement angle (p = 0.001).

CONCLUSION

Rapid maxillary expansion produces subtle changes in the naso-maxillary soft tissue complex. There is an increase in nasal base width, retraction and flattening of the nasal tip. These changes are small, less than 2 mm and variable between patients.

Haptics - touchfeedback technology widening the horizon of medicine

Haptics, or touchsense haptic technology is a major breakthrough in medical and dental interventions. Haptic perception is the process of recognizing objects through touch. Haptic sensations are created by actuators or motors which generate vibrations to the users and are controlled by embedded software which is integrated into the device. It takes the advantage of a combination of somatosensory pattern of skin and proprioception of hand position. Anatomical and diagnostic knowledge, when it is combined with this touch sense technology, has revolutionized medical education. This amalgamation of the worlds of diagnosis and surgical intervention adds precise robotic touch to the skill of the surgeon. A systematic literature review was done by using MEDLINE, GOOGLE SEARCH AND PubMed. The aim of this article was to introduce the fundamentals of haptic technology, its current applications in medical training and robotic surgeries, limitations of haptics and future aspects of haptics in medicine.

The clinical application of three-dimensional motion capture (4D): a novel approach to quantify the dynamics of facial animations

The aim of this pilot study was to evaluate the feasibility of measuring the change in magnitude, speed, and motion similarity of facial animations in head and neck oncology patients, before and after lip split mandibulotomy. Seven subjects (four males, three females) aged 42-80 years were recruited. The subjects were asked to perform four facial animations (maximal smile, lip purse, cheek puff, and grimace) from rest to maximal position. The animations were captured using a Di4D motion capture system, which recorded 60 frames/s. Nine facial soft tissue landmarks were manually digitized on the first frame of the three-dimensional image of each animation by the same operator and were tracked automatically for the sequential frames. The intra-operator digitization error was within 0.4mm. Lip purse and maximal smile animations showed the least amount of change in magnitude (0.2mm) following surgery; speed difference was least for smile animation (-0.1mm/s). Motion similarity was found to be highest for lip purse animation (0.78). This pilot study confirmed that surgery did influence the dynamics of facial animations, and the Di4D capture system can be regarded as a feasible objective tool for assessing the impact of surgical interventions on facial soft tissue movements.

Comparison of three-dimensional surface-imaging systems

BACKGROUND

In recent decades, three-dimensional (3D) surface-imaging technologies have gained popularity worldwide, but because most published articles that mention them are technical, clinicians often have difficulties gaining a proper understanding of them. This article aims to provide the reader with relevant information on 3D surface-imaging systems. In it, we compare the most recent technologies to reveal their differences.

METHODS

We have accessed five international companies with the latest technologies in 3D surface-imaging systems: 3dMD, Axisthree, Canfield, Crisalix and Dimensional Imaging (Di3D; in alphabetical order). We evaluated their technical equipment, independent validation studies and corporate backgrounds.

RESULTS

The fastest capturing devices are the 3dMD and Di3D systems, capable of capturing images within 1.5 and 1 ms, respectively. All companies provide software for tissue modifications. Additionally, 3dMD, Canfield and Di3D can fuse computed tomography (CT)/cone-beam computed tomography (CBCT) images into their 3D surface-imaging data. 3dMD and Di3D provide 4D capture systems, which allow capturing the movement of a 3D surface over time. Crisalix greatly differs from the other four systems as it is purely web based and realised via cloud computing.

CONCLUSION

3D surface-imaging systems are becoming important in today's plastic surgical set-ups, taking surgeons to a new level of communication with patients, surgical planning and outcome evaluation. Technologies used in 3D surface-imaging systems and their intended field of application vary within the companies evaluated. Potential users should define their requirements and assignment of 3D surface-imaging systems in their clinical as research environment before making the final decision for purchase.

Facial Scanning With a Digital Camera: A Novel Way of Screening for Primary Angle Closure

PURPOSE

We hypothesize that patients with primary angle closure (PAC) have common significant facial characteristics that set them apart from an age-matched, sex-matched, and race-matched control population. The primary objective of this study was to test whether a 3-dimensional (3D) camera could pick up these differences in order to differentiate PAC patients from controls.

PATIENTS

A total of 55 patients with PAC and 38 controls were included in the study.

MATERIALS AND METHODS

Cases and controls had their facial photographs taken using a 3-dimensional digital camera (3dMdFace System). The facial features in the captured photographs were analyzed using a computer software (Neural Network Toolbox). A regression formula was devised to show whether these facial parameters could be used to distinguish between patients and controls.

RESULTS

Thirteen facial parameters were measured, and using a regression formula and neural network classification we were able to mathematically distinguish patients from controls using this method of screening.

CONCLUSIONS

PAC patients have distinct facial features that may be differentiated from those of normal individuals mathematically using 3D photography. There is potential for this 3D facial scanning technology in screening for PAC in the general population.

A comparison study of different facial soft tissue analysis methods

OBJECTIVES

The purpose of this study was to evaluate several different facial soft tissue measurement methods.

MATERIALS AND METHODS

After marking 15 landmarks in the facial area of 12 mannequin heads of different sizes and shapes, facial soft tissue measurements were performed by the following 5 methods: Direct anthropometry, Digitizer, 3D CT, 3D scanner, and DI3D system. With these measurement methods, 10 measurement values representing the facial width, height, and depth were determined twice with a one week interval by one examiner. These data were analyzed with the SPSS program.

RESULTS

The position created based on multi-dimensional scaling showed that direct anthropometry, 3D CT, digitizer, 3D scanner demonstrated relatively similar values, while the DI3D system showed slightly different values. All 5 methods demonstrated good accuracy and had a high coefficient of reliability (>0.92) and a low technical error (<0.9 mm). The measured value of the distance between the right and left medial canthus obtained by using the DI3D system was statistically significantly different from that obtained by using the digital caliper, digitizer and laser scanner (p < 0.05), but the other measured values were not significantly different. On evaluating the reproducibility of measurement methods, two measurement values (Ls-Li, G-Pg) obtained by using direct anthropometry, one measurement value (N'-Prn) obtained by using the digitizer, and four measurement values (EnRt-EnLt, AlaRt-AlaLt, ChRt-ChLt, Sn-Pg) obtained by using the DI3D system, were statistically significantly different. However, the mean measurement error in every measurement method was low (<0.7 mm). All measurement values obtained by using the 3D CT and 3D scanner did not show any statistically significant difference.

CONCLUSION

The results of this study show that all 3D facial soft tissue analysis methods demonstrate favorable accuracy and reproducibility, and hence they can be used in clinical practice and research studies.

Design of aerosol face masks for children using computerized 3D face analysis

BACKGROUND

Aerosol masks were originally developed for adults and downsized for children. Overall fit to minimize dead space and a tight seal are problematic, because children's faces undergo rapid and marked topographic and internal anthropometric changes in their first few months/years of life. Facial three-dimensional (3D) anthropometric data were used to design an optimized pediatric mask.

METHODS

Children's faces (n=271, aged 1 month to 4 years) were scanned with 3D technology. Data for the distance from the bridge of the nose to the tip of the chin (H) and the width of the mouth opening (W) were used to categorize the scans into "small," "medium," and "large" "clusters."

RESULTS

"Average" masks were developed from each cluster to provide an optimal seal with minimal dead space. The resulting computerized contour, W and H, were used to develop the SootherMask® that enables children, "suckling" on their own pacifier, to keep the mask on their face, mainly by means of subatmospheric pressure. The relatively wide and flexible rim of the mask accommodates variations in facial size within and between clusters.

CONCLUSIONS

Unique pediatric face masks were developed based on anthropometric data obtained through computerized 3D face analysis. These masks follow facial contours and gently seal to the child's face, and thus may minimize aerosol leakage and dead space.

Three-dimensional methodology for photogrammetric acquisition of the soft tissues of the face: a new clinical-instrumental protocol

Background

The objective of this study is to define an acquisition protocol that is clear, precise, repeatable, simple, fast and that is useful for analysis of the anthropometric characteristics of the soft tissue of the face.

Methods

The analysis was carried out according to a new clinical-instrumental protocol that comprises four distinct phases: (1) setup of portable equipment in the space in which field analysis will be performed, (2) preparation of the subject and spatial positioning, (3) scanning of the subject with different facial expressions, and (4) treatment and processing of data. The protocol was tested on a sample comprising 66 female subjects (64 Caucasian, 1 Ethiopian, and 1 Brazilian) who were the finalists of an Italian national beauty contest in 2010. To illustrate the potential of the method, we report here the measurements and full analysis that were carried out on the facial model of one of the subjects who was scanned.

Results

This new protocol for the acquisition of faces is shown to be fast (phase 1, about 1 h; phase 2, about 1.5 min; phase 3, about 1.5 min; phase 4, about 15 min), simple (phases 1 to 3 requiring a short operator training period; only phase 4 requires expert operators), repeatable (with direct palpation of anatomical landmarks and marking of their positions on the face, the problem of identification of these same landmarks on the digital model is solved), reliable and precise (average precision of measurements, 0.5 to 0.6 mm over the entire surface of the face).

Conclusions

This standardization allows the mapping of the subjects to be carried out following the same conditions in a reliable and fast process for all of the subjects scanned.