Three-dimensional facial growth studied by optical surface scanning

Lip and facial training improves lip-closing strength and facial morphology

OBJECTIVE

Childhood is an important period for lip-closing strength (LCS) development, and failure to acquire LCS during childhood leads to various adverse health effects, such as mouth breathing. The purpose of this study was to examine the effectiveness of device-free lip and facial training in preschool children.

DESIGN

The participants were divided into training and control groups. Both groups comprised 123 children aged 3-4 years, and only the training group received lip and facial training (i.e., opening and closing the lips and protruding the tongue) for 1 year. A two-way repeated measures analysis of variance was applied to compare the interaction effects of LCS and facial linear distance and angle by year (initial year vs. 1 year later) and group (training vs. control group). In addition, paired t-tests were used to test the changes in LCS and facial linear distance and angle after 1 year in both groups. Furthermore, the same analysis was performed in children with weak LCS in both groups (incompetent lip seal [ILS]).

RESULTS

The LCS of children in the training group significantly increased after training compared with that in the control group, whether the analysis included all children or children with ILS alone. Lip and facial training for children with ILS reduced both the upper and lower lip protrusion; children with ILS without training had increased lip protrusion after 1 year.

CONCLUSIONS

Lip and facial training for children with ILS effectively improved LCS and lip morphology, thereby preventing increased lip protrusion.

Three-dimensional analysis of modeled facial aging and sexual dimorphism from juvenile to elderly age

A detailed understanding of craniofacial ontogenetic development is important in a variety of scientific disciplines dealing with facial reconstruction, forensic identification, ageing prediction, and monitoring of pathological growth, including the effect of therapy. The main goals of this study were (1) the construction of the facial aging model using local polynomial regression fitting separately for both sexes, (2) evaluation of the aging effect not only on facial form as a whole but also on dimensions important for clinical practice, and (3) monitoring of the development of shape facial sexual dimorphism. Our study was based on the form and shape analysis of three-dimensional facial surface models of 456 individuals aged 14-83 years. The facial models were obtained using a structured light-based optical scanner and divided (for some analyses) into four age categories (juveniles, young adults, middle adults, and elderly adults). The methodology was based on geometric and classic morphometrics including multivariate statistics. Aging in both sexes shared common traits such as more pronounced facial roundness reducing facial convexity, sagging soft tissue, smaller visible areas of the eyes, greater nose, and thinner lips. In contrast to female faces, male faces increase in size until almost 30 years of age. After the age of 70, male facial size not only stagnates, like in females, but actually decreases slightly. Sexual dimorphic traits tended to diminish in the frontal and orbitonasal areas and increase in the gonial area.

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.

Exploring the midline soft tissue surface changes from 12 to 15 years of age in three distinct country population cohorts

INTRODUCTION

Several studies have highlighted differences in the facial features in a White European population. Genetics appear to have a major influence on normal facial variation, and environmental factors are likely to have minor influences on face shape directly or through epigenetic mechanisms.

AIM

The aim of this longitudinal cohort study is to determine the rate of change in midline facial landmarks in three distinct homogenous population groups (Finnish, Latvian, and Welsh) from 12.8 to 15.3 years of age. This age range covers the pubertal growth period for the majority of boys and girls.

METHODS

A cohort of children aged 12 were monitored for facial growth in three countries [Finland (n = 60), Latvia (n = 107), and Wales (n = 96)]. Three-dimensional facial surface images were acquired (using either laser or photogrammetric methods) at regular intervals (6-12 months) for 4 years. Ethical approval was granted in each country. Nine midline landmarks were identified and the relative spatial positions of these surface landmarks were measured relative to the mid-endocanthion (men) over a 4-year period.

RESULTS

This study reports the children who attended 95 per cent of all scanning sessions (Finland 48 out of 60; Latvia 104 out of 107; Wales 50 out of 96). Considerable facial variation is seen for all countries and sexes. There are clear patterns of growth that show different magnitudes at different age groups for the different country groups, sexes, and facial parameters. The greatest single yearly growth rate (5.4 mm) was seen for Welsh males for men-pogonion distance at 13.6 years of age. Males exhibit greater rates of growth compared to females. These variations in magnitude and timings are likely to be influenced by genetic ancestry as a result of population migration.

CONCLUSION

The midline points are a simple and valid method to assess the relative spatial positions of facial surface landmarks. This study confirms previous reports on the subtle differences in facial shapes and sizes of male and female children in different populations and also highlights the magnitudes and timings of growth for various midline landmark distances to the men point.

Three-dimensional mixed longitudinal study of facial growth changes and variability of facial form in preschool children using stereophotogrammetry

OBJECTIVES

Since the normal, non-pathological facial growth in preschool children is not sufficiently reported, the aim was to follow growth changes of facial surface, sex differences and facial variability in preschool children using 3D stereophotogrammetry.

SETTINGS AND SAMPLE POPULATION

Mixed longitudinal sample of healthy Caucasian preschool children without head and facial trauma or craniofacial anomalies from 3.4 to 6.7 years of age consisted of 25 girls and 17 boys.

MATERIALS AND METHODS

136 3D facial models from optical scanner Vectra 3D were evaluated by geometric morphometrics (CPC-DCA, PCA, per-vertex t test).

RESULTS

In both sexes, the lower face was widened and elongated, and the prominences of the superciliary arches, lower orbital region, nose, lips and chin increased. Facial surface increments were more even in girls with a maximum between the fourth and fifth year of age, while in boys, there was the most intensive growth between fifth and sixth year of age. Sexual dimorphism was very stable during investigated period, only less statistically significant at the age of 3 years. Boys had more prominent lateral lower part of forehead, nose and lips than girls in every age category.

CONCLUSIONS

The longitudinal growth of the face between third and sixth year of age was similar in both sexes, facial sex differences were found in terms of intensity, size and timing. Variability of facial form showed that boys' faces were larger on average and facial shape did not differ. The knowledge of facial growth is essential for diagnostics and clinical practice.

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

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

Simulation of facial growth based on longitudinal data: Age progression and age regression between 7 and 17 years of age using 3D surface data

Modelling of the development of facial morphology during childhood and adolescence is highly useful in forensic and biomedical practice. However, most studies in this area fail to capture the essence of the face as a three-dimensional structure. The main aims of our present study were (1) to construct ageing trajectories for the female and male face between 7 and 17 years of age and (2) to propose a three-dimensional age progression (age -regression) system focused on real growth-related facial changes. Our approach was based on an assessment of a total of 522 three-dimensional (3D) facial scans of Czech children (39 boys, 48 girls) that were longitudinally studied between the ages of 7 to 12 and 12 to 17 years. Facial surface scans were obtained using a Vectra-3D scanner and evaluated using geometric morphometric methods (CPD-DCA, PCA, Hotelling’s T² tests). We observed very similar growth rates between 7 and 10 years in both sexes, followed by an increase in growth velocity in both sexes, with maxima between 11 and 12 years in girls and 11 to 13 years in boys, which are connected with the different timing of the onset of puberty. Based on these partly different ageing trajectories for girls and boys, we simulated the effects of age progression (age regression) on facial scans. In girls, the mean error was 1.81 mm at 12 years and 1.7 mm at 17 years. In boys, the prediction system was slightly less successful: 2.0 mm at 12 years and 1.94 mm at 17 years. The areas with the greatest deviations between predicted and real facial morphology were not important for facial recognition. Changes of body mass index percentiles in children throughout the observation period had no significant influence on the accuracy of the age progression models for both sexes.

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.

Three-Dimensional Imaging in Orthodontics

Orthodontic records are one of the main milestones in orthodontic therapy. Records are essential not only for diagnosis and treatment planning but also for follow-up of the case, communicating with colleagues, and evaluating the treatment outcomes. Recently, two-dimensional (2D) imaging technology, such as cephalometric and panoramic radiographs and photographs, and plaster models were routinely used. However, after the introduction of three-dimensional (3D) technologies (laser scanner, stereophotogrammetry, and computed tomography) into dentistry, 3D imaging systems are more and more commonly preferred than 2D, especially in cases with craniofacial deformities. In fact, 3D imaging provided more detailed and realistic diagnostic information about the craniofacial hard as well as soft tissue and allowed to perform easier, faster, and more reliable 3D analyses. The purpose of this review is to provide an overview of the 3D imaging techniques, including their advantages and disadvantages, and to outline the indications for 3D imaging.

Hypermasculinised facial morphology in boys and girls with Autism Spectrum Disorder and its association with symptomatology

Elevated prenatal testosterone exposure has been associated with Autism Spectrum Disorder (ASD) and facial masculinity. By employing three-dimensional (3D) photogrammetry, the current study investigated whether prepubescent boys and girls with ASD present increased facial masculinity compared to typically-developing controls. There were two phases to this research. 3D facial images were obtained from a normative sample of 48 boys and 53 girls (3.01-12.44 years old) to determine typical facial masculinity/femininity. The sexually dimorphic features were used to create a continuous 'gender score', indexing degree of facial masculinity. Gender scores based on 3D facial images were then compared for 54 autistic and 54 control boys (3.01-12.52 years old), and also for 20 autistic and 60 control girls (4.24-11.78 years). For each sex, increased facial masculinity was observed in the ASD group relative to control group. Further analyses revealed that increased facial masculinity in the ASD group correlated with more social-communication difficulties based on the Social Affect score derived from the Autism Diagnostic Observation Scale-Generic (ADOS-G). There was no association between facial masculinity and the derived Restricted and Repetitive Behaviours score. This is the first study demonstrating facial hypermasculinisation in ASD and its relationship to social-communication difficulties in prepubescent children.

Recognition of children on age-different images: Facial morphology and age-stable features

The situation of missing children is one of the most emotional social issues worldwide. The search for and identification of missing children is often hampered, among others, by the fact that the facial morphology of long-term missing children changes as they grow. Nowadays, the wide coverage by surveillance systems potentially provides image material for comparisons with images of missing children that may facilitate identification. The aim of study was to identify whether facial features are stable in time and can be utilized for facial recognition by comparing facial images of children at different ages as well as to test the possible use of moles in recognition. The study was divided into two phases (1) morphological classification of facial features using an Anthropological Atlas; (2) algorithm developed in MATLAB® R2014b for assessing the use of moles as age-stable features. The assessment of facial features by Anthropological Atlases showed high mismatch percentages among observers. On average, the mismatch percentages were lower for features describing shape than for those describing size. The nose tip cleft and the chin dimple showed the best agreement between observers regarding both categorization and stability over time. Using the position of moles as a reference point for recognition of the same person on age-different images seems to be a useful method in terms of objectivity and it can be concluded that moles represent age-stable facial features that may be considered for preliminary recognition.

The extended tentacles of laser - From diagnosis to treatment in orthodontics: An overview

Since the introduction of lasers in dentistry in the mid-1990's, research in laser supported dental therapies is progressing at a rapid pace. Orthodontics is no exception. In orthodontics, lasers have many diagnostic, therapeutic, and biomodulating applications. To update the various applications of lasers in orthodontics. Lasers work by delivering energy in the form of light. Laser, striking the biological tissues can either get reflected, absorbed or scattered depending on several factors. Depending on the fate of the emitted laser, it can be applied for different diagnostic, therapeutic and surgical procedures. The knowledge and understanding of different types of lasers and its specific applications is a prerequisite before it can be applied beneficially. In Orthodontics, the versatility of laser has expanded into bonding, curing, debonding, imaging, growth modification, pain reduction, etc. Definitely laser has extended its tentacles from diagnosis to treatment in orthodontics.

Morphological differences of facial soft tissue contours from child to adult of Japanese males: a three-dimensional cross-sectional study

OBJECTIVE

To evaluate morphological differences of the facial soft tissue surface between male Japanese adults and children.

DESIGN

20 adult Japanese males (average age 28 years) and 20 Japanese boys (average age 5.5 years) with normal occlusion were selected for this study. The images of the subjects' facial surface were obtained with a 3-D laser scanner. To evaluate the three-dimensional morphological differences of the facial soft tissue, we transformed the coordinates of 16 facial landmarks to a new reference plane and compared the adults' and children's facial form drawn to the same scale in the same coordinate system.

RESULTS

The morphological difference ratio of the lower facial area was higher than in the upper facial area, and the nose and lower face changed more forward than downward. The morphological difference ratio of the mid face width was smaller than other areas.

CONCLUSION

Our study suggests that the morphological facial soft tissue differences between Japanese adults and children are more forward and downward than laterally, manifesting in a facial form of adults that is deeper and narrow.

Three-dimensional simulation of scalp soft tissue expansion using finite element method

Scalp soft tissue expansion is one of the key medical techniques to generate new skin tissue for correcting various abnormalities and defects of skin in plastic surgery. Therefore, it is very important to work out the appropriate approach to evaluate the increase of expanded scalp area and to predict the shape, size, number, and placement of the expander. A novel method using finite element model is proposed to solve large deformation of scalp expansion in this paper. And the procedure to implement the scalp tissue expansion with finite element method is also described in detail. The three-dimensional simulation results show that the proposed method is effective, and the analysis of simulation experiment shows that the volume and area of the expansion scalp can be accurately calculated and the quantity, location, and size of the expander can also be predicted successfully with the proposed model.

Hemimandibular hypertrophy - hybrid variants: report of two cases

Hemimandibular hypertrophy and its variants result from unilateral excessive growth of the mandible and involve both the body and ramus of mandible. This causes facial asymmetry and in turn accompanying psychological problems. In this report we discuss use of imaging in diagnosis of these lesions and investigate the different variants.

Laser in dentistry: An innovative tool in modern dental practice

The term LASER is an acronym for ‘Light Amplification by the Stimulated Emission of Radiation’. As its first application in dentistry by Miaman, in 1960, the laser has seen various hard and soft tissue applications. In the last two decades, there has been an explosion of research studies in laser application. In hard tissue application, the laser is used for caries prevention, bleaching, restorative removal and curing, cavity preparation, dentinal hypersensitivity, growth modulation and for diagnostic purposes, whereas soft tissue application includes wound healing, removal of hyperplastic tissue to uncovering of impacted or partially erupted tooth, photodynamic therapy for malignancies, photostimulation of herpetic lesion. Use of the laser proved to be an effective tool to increase efficiency, specificity, ease, and cost and comfort of the dental treatment.

Assessment of facial asymmetry in growing subjects with a three-dimensional laser scanning system

OBJECTIVES

To evaluate facial asymmetry in growing subjects with no malocclusion on three-dimensional laser facial scans.

SETTING AND SAMPLE POPULATION

Twenty-seven healthy Caucasian children (15 boys and 12 girls, aged 5.4 ± 0.3 years) in the primary dentition without malocclusion were randomly selected from a local kindergarten in Slovenia.

MATERIAL AND METHODS

Surface facial images were obtained using a three-dimensional laser scanning system at baseline and at 18, 30, 42 and 54 months of follow-up. Facial asymmetry was assessed quantitatively by measuring the average distance between facial image and mirrored image. Further, the percentage of asymmetry was calculated as the percentage of image to mirrored image not coinciding within 0.5 mm. Qualitative assessment was performed on colour deviation maps by recording the predominant side of the face for the upper, middle and lower parts of the face separately. Nonparametric tests were used for data analysis.

RESULTS

No face was perfectly symmetric. The average distance between the mirrored images for the whole face ranged 0.22-0.85 mm and the percentage of asymmetry 7.8-66.9. There were no significant gender differences (p > 0.05), and no significant change was found over the observed period. The upper part of the face was the least asymmetric, while the lower and middle parts showed similar degrees of asymmetry.

CONCLUSION

Facial asymmetry is already present at an early developmental stage and does not show any tendency to increase or decrease with growth in the pre-pubertal period.

Three-dimensional analysis of lip and perioral soft tissue changes after debonding of labial brackets

OBJECTIVES

To evaluate the possible soft tissue changes after debonding of labial brackets using three-dimensional (3D) images acquired by a laser scanner.

METHODS

On the same day, 3D facial scans were taken immediately before debonding (T1) and immediately after debonding (T2) from 53 patients, and follow-up scans were taken 3 months after debonding (T3) from 31 patients. To compare the scans, superimpositions were performed and shell-to-shell deviations were used for quantitative analysis.

RESULTS

Shell-to-shell deviation map showing warm colors in lip and perioral tissue represented the retrusion of soft tissue after bracket removal. Soft tissue retrusion was significant for all landmarks immediately after debonding (T1-T2) and 3 months after debonding (T1-T3). Gender, bracket type, and the lip thickness variables did not show a clinically significant influence on the amount of soft tissue retrusion at the T1-T3 period. Lip corners and vermilion borders were significantly retruded at the T1-T3 period more than other perioral areas. A negative linear relationship was found in the amount of soft tissue retrusion immediately after debonding (T1-T2) and from debonding to 3 months after debonding (T2-T3).

CONCLUSION

Three-dimensional imaging showed significant changes in lip and perioral soft tissue after debonding of labial brackets. Clinically significant changes, approximately 2 mm of retrusion, occurred in the mouth corners bilaterally. Vermilion border landmarks also demonstrated significant changes in more than 1 mm. However, it was not possible to predict the soft tissue changes. A wide range of individual variability in the response to treatment and soft tissue adaptation was noted.

Improved facial outcome assessment using a 3D anthropometric mask

The capacity to process three-dimensional facial surfaces to objectively assess outcomes of craniomaxillofacial care is urgently required. Available surface registration techniques depart from conventional facial anthropometrics by not including anatomical relationship in their analysis. Current registrations rely on the manual selection of areas or points that have not moved during surgery, introducing subjectivity. An improved technique is proposed based on the concept of an anthropometric mask (AM) combined with robust superimposition. The AM is the equivalent to landmark definitions, as used in traditional anthropometrics, but described in a spatially dense way using (∼10.000) quasi-landmarks. A robust superimposition is performed to align surface images facilitating accurate measurement of spatial differences between corresponding quasi-landmarks. The assessment describes magnitude and direction of change objectively and can be displayed graphically. The technique was applied to three patients, without any modification and prior knowledge: a 4-year-old boy with Treacher-Collins syndrome in a resting and smiling pose; surgical correction for hemimandibular hypoplasia; and mandibular hypoplasia with staged orthognathic procedures. Comparisons were made with a reported closest-point (CP) strategy. Contrasting outcomes were found where the CP strategy resulted in anatomical implausibility whilst the AM technique was parsimonious to expected differences.

The assessment of facial variation in 4747 British school children

The aim of this study is to identify key components contributing to facial variation in a large population-based sample of 15.5-year-old children (2514 females and 2233 males). The subjects were recruited from the Avon Longitudinal Study of Parents and Children. Three-dimensional facial images were obtained for each subject using two high-resolution Konica Minolta laser scanners. Twenty-one reproducible facial landmarks were identified and their coordinates were recorded. The facial images were registered using Procrustes analysis. Principal component analysis was then employed to identify independent groups of correlated coordinates. For the total data set, 14 principal components (PCs) were identified which explained 82 per cent of the total variance, with the first three components accounting for 46 per cent of the variance. Similar results were obtained for males and females separately with only subtle gender differences in some PCs. Facial features may be treated as a multidimensional statistical continuum with respect to the PCs. The first three PCs characterize the face in terms of height, width, and prominence of the nose. The derived PCs may be useful to identify and classify faces according to a scale of normality.

Novel method of 3-dimensional soft-tissue analysis for Class III patients

INTRODUCTION

The aim of this study was to evaluate 3-dimensional facial shells by incorporating a population-specific average template with a group of Class III subjects preparing to have orthognathic surgery.

METHODS

The Class III group included 14 male (MCIII) and 15 female (FCIII) subjects. We used 43 male and 44 female Class I subjects to construct average male (AvM) and female (AvF) faces. Coordinates of 3 points on the facial templates of groups MCIII and FCIII and the templates AvM and AvF were compared. MCIII-AvM and FCIII-AvF superimpositions were evaluated for differences.

RESULTS

Vertical distances (sella to soft-tissue pogonion) were statistically significantly higher for the AvM (9.1%) and MCIII (10.1%) than for the AvF and FCIII, respectively (P < 0.05). The distances of soft-tissue pogonion in the horizontal x-axis were positive in 80% of the FCIII group and 85.7% of the MCIII group. The Class III subjects differed from the average face in the lower two thirds, but, in 50% (MCIII) and 60% (FCIII), they differed also in the upper facial third.

CONCLUSIONS

(1) The average and Class III Slovenian male morphologic face heights are statistically significantly higher than those of the female subjects. (2) The Slovenian Class III male and female subjects tend toward a left-sided chin deviation. (3) Differences between Class III patients and a normative data set were determined.

Registration of 3-dimensional facial photographs for clinical use

PURPOSE

To objectively evaluate treatment outcomes in oral and maxillofacial surgery, pre- and post-treatment 3-dimensional (3D) photographs of the patient's face can be registered. For clinical use, it is of great importance that this registration process is accurate (< 1 mm). The purpose of this study was to determine the accuracy of different registration procedures.

MATERIALS AND METHODS

Fifteen volunteers (7 males, 8 females; mean age, 23.6 years; range, 21 to 26 years) were invited to participate in this study. Three-dimensional photographs were captured at 3 different times: baseline (T(0)), after 1 minute (T(1)), and 3 weeks later (T(2)). Furthermore, a 3D photograph of the volunteer laughing (T(L)) was acquired to investigate the effect of facial expression. Two different registration methods were used to register the photographs acquired at all different times: surface-based registration and reference-based registration. Within the surface-based registration, 2 different software packages (Maxilim [Medicim NV, Mechelen, Belgium] and 3dMD Patient [3dMD LLC, Atlanta, GA]) were used to register the 3D photographs acquired at the various times. The surface-based registration process was repeated with the preprocessed photographs. Reference-based registration (Maxilim) was performed twice by 2 observers investigating the inter- and intraobserver error.

RESULTS

The mean registration errors are small for the 3D photographs at rest (0.39 mm for T(0)-T(1) and 0.52 mm for T(0)-T(2)). The mean registration error increased to 1.2 mm for the registration between the 3D photographs acquired at T(0) and T(L). The mean registration error for the reference-based method was 1.0 mm for T(0)-T(1), 1.1 mm for T(0)-T(2), and 1.5 mm for T(0) and T(L). The mean registration errors for the preprocessed photographs were even smaller (0.30 mm for T(0)-T(1), 0.42 mm for T(0)-T(2), and 1.2 mm for T(0) and T(L)). Furthermore, a strong correlation between the results of both software packages used for surface-based registration was found. The intra- and interobserver error for the reference-based registration method was found to be 1.2 and 1.0 mm, respectively.

CONCLUSION

Surface-based registration is an accurate method to compare 3D photographs of the same individual at different times. When performing the registration procedure with the preprocessed photographs, the registration error decreases. No significant difference could be found between both software packages that were used to perform surface-based registration.

Use of 3-dimensional surface acquisition to study facial morphology in 5 populations

INTRODUCTION

The aim of this study was to assess the use of 3-dimensional facial averages for determining morphologic differences from various population groups.

METHODS

We recruited 473 subjects from 5 populations. Three-dimensional images of the subjects were obtained in a reproducible and controlled environment with a commercially available stereo-photogrammetric camera capture system. Minolta VI-900 (Konica Minolta, Tokyo, Japan) and 3dMDface (3dMD LLC, Atlanta, Ga) systems were used. Each image was obtained as a facial mesh and orientated along a triangulated axis. All faces were overlaid, one on top of the other, and a complex mathematical algorithm was performed until average composite faces of 1 man and 1 woman were achieved for each subgroup. These average facial composites were superimposed based on a previously validated superimposition method, and the facial differences were quantified.

RESULTS

Distinct facial differences were observed among the groups. The linear differences between surface shells ranged from 0.37 to 1.00 mm for the male groups. The linear differences ranged from 0.28 and 0.87 mm for the women. The color histograms showed that the similarities in facial shells between the subgroups by sex ranged from 26.70% to 70.39% for men and 36.09% to 79.83% for women. The average linear distance from the signed color histograms for the male subgroups ranged from -6.30 to 4.44 mm. The female subgroups ranged from -6.32 to 4.25 mm.

CONCLUSIONS

Average faces can be efficiently and effectively created from a sample of 3-dimensional faces. Average faces can be used to compare differences in facial morphologies for various populations and sexes. Facial morphologic differences were greatest when totally different ethnic variations were compared. Facial morphologic similarities were present in comparable groups, but there were large variations in concentrated areas of the face.

Facial morphology of Slovenian and Welsh white populations using 3-dimensional imaging

OBJECTIVE

To use 3-dimensional (3D) facial averages to test the hypothesis that the facial morphologies of 2 European white groups (Slovenia and Wales) have no differences.

METHODS

Fifty males and 50 females from Wales and 43 males and 44 females from Slovenia were included in the study. Subjects ranged from 18 to 30 years of age. Four subgroups were formed: Slovenian males (SM), Slovenian females (SF), Welsh males (WM), and Welsh females (WF). 3D data were acquired using a laser scanning system. An average face for each subgroup was obtained using a previously validated mathematical algorithm. Facial differences were quantified after average faces had been superimposed using a previously validated method.

RESULTS

A total of 187 subjects from Slovenia and Wales formed 4 gender-specific subgroups. Absolute differences between subgroups ranged from 0.36 mm to 1.51 mm. The mean linear facial difference between SF and WF was 0.64 +/- 0.51 mm, and between SM and WM was 0.36 +/- 0.41 mm. Similarities between subgroups ranged from 13.43% (SF, WF) to 70.23% (SM, WM). Slovenian males and females tend to express Class III facial morphology when compared with the Welsh gender-specific subgroups. Male faces, in general, have more pronounced nasal, brow, and frontal regions and mandibles when compared with females. Female faces have more prominent malar and periocular areas.

CONCLUSION

The hypothesis is rejected. Morphologic differences exist between Slovenian and Welsh faces.

Early crossbite correction: a three-dimensional evaluation

A crossbite (CB) occurs in approximately 4-23 per cent of young children and may lead to mandibular and facial asymmetry. Therefore, early intervention is often necessary to create conditions for normal occlusal and facial development. The aim of this study was to assess facial asymmetry and palatal volume (pre- and post-treatment) in two groups of children, one with a unilateral CB and the other with no crossbite (NCB). Thirty children with CB (13 males, 17 females, mean age 4.9 +/- 0.98 years) and 28 children with NCB (17 males, 11 females, mean age 5.3 +/- 0.36 years) were included in the study. Those with a CB were treated with an intra-oral expansion appliance. The faces and dental casts of the children were scanned using a three-dimensional (3D) laser scanning device at baseline (T0) and after six months (T1) of treatment. Student's t-tests were used to assess differences between the two groups in facial symmetry and palatal volume over the 6 month period. The CB children had statistically significantly greater asymmetry of the face (P = 0.042), especially the lower third (P = 0.039), and a significantly smaller palatal volume (P = 0.045) than the NCB subjects at baseline. There were no statistically significant differences between the two groups at T1. Treatment of a CB in the primary dentition corrected the facial asymmetry, particularly the lower part of the face. The palatal volume of the CB children increased as a result of orthodontic intervention to similar levels exhibited by the NCB children.

Three-dimensional analysis of facial morphology surface changes in untreated children from 12 to 14 years of age

INTRODUCTION

The developing face is of interest to orthodontists, especially if orthodontic treatment can influence the outcome of facial growth. New 3-dimensional (3D) modalities have enabled clinicians to better understand the facial changes in a developing child.

METHODS

Fifty-nine children with normal body mass indexes were evaluated with a previously validated 3D laser imaging device over a 2-year period. Surface changes were evaluated on normal and average faces. These changes were seen as mean surface changes and color maps.

RESULTS

The results suggest that the surface areas of change in average faces were generally downward and forward with respect to the nose and soft-tissue nasion. The lips also translated in a downward direction as the nose grew, and there was a general increase in the vertical dimension. Some subjects were in the "great changes" category, boys significantly more so than girls.

CONCLUSIONS

The following conclusions can be made from this 3D study of changes of facial morphology in children: (1) surface changes are greater in boys than in girls; (2) differences in the timing of surface changes in boys and girls are clinically significant, with boys exhibiting more changes later; (3) positive surface changes occur in the nose, brows, lips, and vertical dimensions of the face; (4) the eyes deepen, and the cheeks become flatter; and (5) 3D imaging is a useful tool in analyzing changes to the face over time.

A three-dimensional look for facial differences between males and females in a British-Caucasian sample aged 151/2 years old

BACKGROUND

Optical surface scanning accurately records the three-dimension (3D) shape of the face non-invasively. Many software programs have been developed to process and analyze the 3D data, enabling the clinicians to create average templates for groups of subjects to provide a comparison of facial shape.

OBJECTIVE

Differences in facial morphology of males and females were identified using a laser scan imaging technology.

SUBJECTS AND METHODS

This study was undertaken on 380 British-Caucasian children aged 15 and a half year old, recruited from the Avon Longitudinal Study of Parents and Children (ALSPAC). 3D facial images were obtained for each individual using two high resolution Konica/Minolta laser scanners. The scan quality was assessed and any unsuitable scans were excluded from the study. Average facial templates were created for males and females, and a registration technique was used to superimpose the facial shells of males and females so that facial differences can be quantified.

RESULTS

Thirty unsuitable scans were excluded from the study. The final sample consisted of 350 subjects (166 females, 184 males). Females tend to have more prominent eyes and cheeks in relation to males with a maximum difference of 2.4 mm. Males tend to have more prominent noses and mouths with a maximum difference of 2.7 mm. About 31% of the facial shells match exactly (no difference), mainly in the forehead and chin regions of the face.

CONCLUSIONS

Differences in facial morphology can be accurately quantified and visualized using 3D imaging technology. This method of facial assessment can be recommended and applied for future research studies to assess facial soft tissue changes because of growth or healthcare intervention.

A Three-Dimensional Evaluation of Postoperative Swelling following Orthognathic Surgery at 6 Months

BACKGROUND

Advances in three-dimensional technology have enabled applications for the clinical setting to be created and used in routine diagnosis, treatment planning, and patient education. The objectives of this prospective clinical trial were to determine the volume changes associated with facial swelling following orthognathic surgery.

METHODS

Twelve subjects requiring orthognathic surgery were recruited for the study. Laser scanned images of the subjects were obtained under a reproducible, controlled environment with two laser-scanning devices assembled as a stereo pair. Three-dimensional laser scans were recorded over six time periods, as follows: T1, presurgical scan; T2, 1 day postoperatively; T3, 1 week postoperatively; T4, 1 month postoperatively; T5, 3 months postoperatively; and T6, 6 months postoperatively.

RESULTS

The results showed a clinical difference in the mean shell deviations between bimaxillary and single-jaw orthognathic surgery. Furthermore, the results suggest that the mean volume of swelling was reduced by approximately 60 percent within the first month after surgery. Finally, the amounts of swelling following surgery were greater in bimaxillary cases. The recovery in the swelling was also faster in this group of patients.

CONCLUSIONS

Three-dimensional imaging has opened up new avenues of patient care and treatment evaluation. The results have shown that the laser scanning device and the method described are a reliable and accurate measure of facial swelling following surgery.

2D:4D and sexually dimorphic facial characteristics

The second-to-fourth-digit ratio (2D:4D) may be related to prenatal testosterone and estrogen levels and pubertal face growth. Several studies have recently provided evidence that 2D:4D is associated with other-rated facial masculinity and dominance, but not with facialmetric measures of masculinity. We found that localized face shape differences, shown here to be sexually dimorphic and related to ratings of dominance, were associated with direct and indirect measurements of 2D:4D. In this study we examined various localized features of the face, showing nose width, jaw angle, and lip height to be sexually dimorphic. We then had faces rated for dominance and saw that the most dimorphic characteristics were those most associated with rated dominance, with typically masculine characteristics tending to be associated with high ratings of dominance. Finally, 2D:4D measurements were made using three different techniques. High (feminine) values of 2D:4D were associated with feminine facial characteristics in women, but not in men. It was concluded that certain aspects of facial development are governed by factors that are established prenatally. These aspects may be associated with perceptions of the self by others that are important in the social environment, particularly in terms of intra-sexual competition and mate acquisition.

The use of three-dimensional imaging in orthodontics

The article illustrates the value of three-dimensional imaging of the face and jaws in the diagnosis and treatment of patients. The applications of programs that have been written for the analysis of facial form are also described, including registration and prediction. The use of the Procrustes analysis is demonstrated in groups of children and adults to differentiate between male and female facial morphology. The use of scanning in forensic science is also described. The application of surface shape analysis to groups of monozygotic and dizygotic twins and to family studies to detect those areas that are genetically determined from those areas, which are not, is illustrated.

The 3-Dimensional Construction of the Average 11-Year-Old Child Face: A Clinical Evaluation and Application

PURPOSE

This article describes construction of the average face and its application in the clinical environment.

SUBJECTS AND METHODS

A total of 72 children, mean age 11.8 years, were selected for the study. Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with 2 Minolta Vivid 900 (Minolta, Osaka, Japan) optical laser-scanning devices assembled as a stereo pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 seconds. These scanned images were processed and merged to form a composite 3-dimensional soft tissue reproduction of the subjects using commercially-available reverse modeling software. The differences in facial morphology were measured using shell deviation color maps. The average face was used to compare differences between male and female groups and 3 subjects with craniofacial anomalies.

RESULTS

The difference between the average male and female face was 0.460 +/- 0.353 mm. The areas of greatest deviation were at the zygomatic area and lower jaw line, with the males being more prominent. The results of the surface deviation between the subjects with craniofacial anomalies were significant.

CONCLUSIONS

The construction of the average face provides an interesting perspective into measuring changes in groups of patients and also acts as a useful template for the comparison of craniofacial anomalies.

Facial templates: a new perspective in three dimensions

PURPOSE

This paper describes the use of adult facial template in gender-specific facial analysis.

SUBJECTS AND METHODS

Eighty adults, mean age 24.5, were selected for the study. Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. These scanned images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software. The differences in facial morphology were measured using shell deviation colour maps. The facial template was used to compare differences between males vs. females groups and two subjects with facial disproportions.

RESULTS

The difference between the male and female facial templates was 1.28 +/- 1.02 mm. The areas of greatest deviation were at the nasal, zygomatic area and lower jaw line. The results of the surface deviation maps between the templates and subjects with facial disproportion showed that the results could be applied for orthodontic diagnosis.

CONCLUSIONS

The construction of the adult facial templates provides an interesting perspective into measuring changes in groups of patients and also acts as a useful template for the comparison of skeletal disproportion.

A new method for the 3D measurement of postoperative swelling following orthognathic surgery

OBJECTIVE

To describe a new method for measuring facial swelling following orthognathic surgery using a 3D laser-scanning device.

DESIGN

Prospective clinical trial. Setting and Sample Population -- University Dental Hospital, Wales College of Medicine, Biology Life and Health Sciences. Three subjects requiring bi-maxillary orthognathic surgery were recruited for the study.

EXPERIMENTAL VARIABLES

Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. 3D laser scans were recorded over six time periods (T1 -- pre-surgical scan, postoperatively: T2 -- 1 day, T3 -- 1 week, T4 -- 1 month, T5 -- 3 months and T6 -- 6 months).

OUTCOME MEASURE

Facial scans from different time periods were overlaid onto the baseline (T6) facial scan to determine the reduction and changes in swelling following orthognathic surgery.

RESULTS

The results showed that swelling could be accurately quantified following surgery. Furthermore, there was a significant reduction in the amount of swelling 1 month postoperatively. Furthermore, the facial morphology returned to approximately 90% of the baseline facial scan at 3 months.

CONCLUSION

The 3D laser-scanning device and the method described was a reliable and accurate measure of facial swelling following surgery.

Construction and use of facial archetypes in anthropology and syndrome diagnosis

This paper describes the benefits of moving from recording simple Euclidian distances and angles between landmarks on the face to full three-dimensional visualisation and mapping using modern optical scanning techniques. Pilot experiments are reported on that strive to create facial archetypes which are accurately descriptive of various cohorts of people. Issues considered include variation amongst people of the same sex, age and population-of-origin. The study has discovered that very few people are needed to construct an "average" face, which is measurably indistinguishable from another average constructed using the faces of other people from within the group studied. This discovery has given the researchers confidence in the reliability of the archetypes which they have produced and this is important if such an analytical technique is to find application in discriminating between peoples on a population basis and in syndrome diagnosis.

Reliability of measuring facial morphology with a 3-dimensional laser scanning system

INTRODUCTION

The purpose of this prospective clinical trial was to evaluate the reliability of a 3-dimensional facial scanning technique for the measurement of facial morphology.

METHODS

A field study was conducted in 2 comprehensive schools in the South Wales region of the United Kingdom. Forty subjects, mean age 11 years 3 months, were analyzed for soft tissue changes at baseline (T1), within 3 minutes (T2), and 3 days later (T3) by using 2 commercially available Minolta Vivid 900 (Osaka, Japan) laser-scanning devices assembled as a stereo pair. Left and right images were merged to form the whole face, and these images were superimposed to assess the errors at T1 and T2, and T1 and T3.

RESULTS

The results showed that premerged left and right mean shell deviations were 0.38 +/- 0.14 mm for scans at T1, 0.31 +/- 0.09 mm at T2, and 0.34 +/- 0.12 mm at T3. The mean differences of the merged composite face were 0.31 +/- 0.08 mm between T1 and T2, and 0.40 +/- 0.11 mm between T1 and T3. Paired t tests showed no significant difference between these groups (P > .05). Shell deviation facial maps of the merged scans showed that 90% of the created composite facial scans were within an error of 0.85 mm.

CONCLUSIONS

Capturing the soft tissue morphology of the face with this technique is clinically reproducible within 3 minutes and 3 days of the initial records.

The investigation of the changing facial appearance of identical twins employing a three-dimensional laser imaging system

OBJECTIVE

An investigation to determine the changing facial appearance of identical twins.

DESIGN

Clinical study.

MATERIALS AND METHODS

Two Minolta Vivid 900 3D optical laser scanners were placed as a stereo pair to capture the soft tissues of a pair of identical twins. Each scan took approximately 2.5 s. The scanned whole faces were superimposed to determine changes in facial morphologies at different time intervals.

OUTCOME MEASURES

The shell deviations between left and right scans of each patient were recorded and analysed for differences. Furthermore, final merged faces were overlaid to determine the changes in facial morphology over time.

RESULTS

The results showed that changes in height and weight correlated with changes in facial morphology.

CONCLUSION

The 3D laser scanning device is a clinically useful tool in the study of facial growth and facial morphology in a pair of twins.

Update in three-dimensional imaging in facial plastic surgery

PURPOSE OF REVIEW

Facial plastic surgeons have always relied on photography for preoperative and postoperative analysis, medicolegal documentation, and communication. The current standards for analysis and documentation of facial structures have been determined by obtaining measurements and parameters from two-dimensional photographs or radiographs. However, the face and neck are three-dimensional structures and require manipulation in three planes within the constraints of esthetics, stability, and function. Recent advances in technology have made three-dimensional imaging and analysis possible.

RECENT FINDINGS

The ability to capture images in three dimensions has opened up new avenues for observation and has increased the ability to analyze changes after surgery. Whereas only linear distances, angles, and areas can be determined by use of two-dimensional images, soft tissue volumetric data and surface topography can also be measured accurately; this can be helpful in validating changes in patients undergoing aging facial or orthognathic procedures. Recent studies have focused on descriptions of imaging techniques, validation of measurements, and the creation of normative data and its applications in surgery.

SUMMARY

The availability of three-dimensional imaging and software systems presents new opportunities for the facial cosmetic surgeon to plan, execute, and assess the outcomes in patients undergoing surgery of the face and neck.

Three-dimensional technology for documentation and record keeping for patients with facial clefts

The surface laser scanner has great potential as a method for documentation of cleft infant due to its accuracy, ease of use, and convenience. The image scan be stored in the computer for easy access. As purchasing costs decrease, its acquisition will be facilitated, resulting in an increase in its use.

Craniofacial applications of three-dimensional laser surface scanning

Recent innovations in technology have generated a variety of techniques for medical imaging. One of these initially developed for industry is laser surface scanning. Laser surface scanning is a noninvasive method for acquiring three-dimensional (3D) images. In this article, the technology of 3D laser surface scanning is described, and a few applications are reported as it relates to craniofacial research and clinical practice. Advantages and disadvantages of this imaging modality are discussed. Three-dimensional laser surface scanning holds great promise as it relates to the documentation, analysis, and evaluation of treatment results in craniofacial anomalies.