3D Landmarks Research Articles

Learning-based local-to-global landmark annotation for automatic 3D cephalometry

The annotation of three-dimensional (3D) cephalometric landmarks in 3D computerized tomography (CT) has become an essential part of cephalometric analysis, which is used for diagnosis, surgical planning, and treatment evaluation. The automation of 3D landmarking with high-precision remains challenging due to the limited availability of training data and the high computational burden. This paper addresses these challenges by proposing a hierarchical deep-learning method consisting of four stages: 1) a basic landmark annotator for 3D skull pose normalization, 2) a deep-learning-based coarse-to-fine landmark annotator on the midsagittal plane, 3) a low-dimensional representation of the total number of landmarks using variational autoencoder (VAE), and 4) a local-to-global landmark annotator. The implementation of the VAE allows two-dimensional-image-based 3D morphological feature learning and similarity/dissimilarity representation learning of the concatenated vectors of cephalometric landmarks. The proposed method achieves an average 3D point-to-point error of 3.63 mm for 93 cephalometric landmarks using a small number of training CT datasets. Notably, the VAE captures variations of craniofacial structural characteristics.

Variation in brown rat cranial shape shows directional selection over 120years in New York City.

Urbanization exposes species to novel environments and selection pressures that may change morphological traits within a population. We investigated how the shape and size of crania and mandibles changed over time within a population of brown rats (Rattus norvegicus) living in Manhattan, New York, USA, a highly urbanized environment. We measured 3D landmarks on the cranium and mandible of 62 adult individuals sampled in the 1890s and 2010s. Static allometry explained approximately 22% of shape variation in crania and mandible datasets, while time accounted for approximately 14% of variation. We did not observe significant changes in skull size through time or between the sexes. Estimating the P‐matrix revealed that directional selection explained temporal change of the crania but not the mandible. Specifically, rats from the 2010s had longer noses and shorter upper molar tooth rows, traits identified as adaptive to colder environments and higher quality or softer diets, respectively. Our results highlight the continual evolution to selection pressures. We acknowledge that urban selection pressures impacting cranial shape likely began in Europe prior to the introduction of rats to Manhattan. Yet, our study period spanned changes in intensity of artificial lighting, human population density, and human diet, thereby altering various aspects of rat ecology and hence pressures on the skull.

A method for similarity assessment between death masks and portraits through linear projection: The case of Vincenzo Bellini

The aim of this study was to confirm the identities of numerous portraits attributed to the composer Vincenzo Bellini by using 3D-to-2D projection. This study also followed on from earlier research on three death masks of Bellini, the results of which had shown that the wax mask in Catania’s Bellini museum best represented Bellini’s face compared to the other two. This study used the aforementioned 3D wax death mask obtained through Reverse Engineering as a reference for a morphometric comparison with 14 other portraits. For each portrait, the linear 3D-to-2D transformation M was found which minimized the distance between the 2D landmarks in the picture and the projected landmarks on the 3D mask. This normalized the distances considering the scale of the portrait and the final dissimilarity score with the mask. In particular, the analytical results were able to identify two portraits which particularly resembled the 3D death mask providing future researchers with the chance to carry out historical-artistic evaluations. We were also able to develop a new tool – Image Mark Pro - to easily annotate 2D images by introducing landmark locations. Since it was so reliable for manually annotating landmarks, we decided to make it publicly available for future research.

Intraspecific variation in the cochleae of harbour porpoises (Phocoena phocoena) and its implications for comparative studies across odontocetes.

In morphological traits, variation within species is generally considered to be lower than variation among species, although this assumption is rarely tested. This is particularly important in fields like palaeontology, where it is common to use a single individual as representative of a species due to the rarity of fossils. Here, we investigated intraspecific variation in the cochleae of harbour porpoises (Phocoena phocoena). Interspecific variation of cochlear morphology is well characterised among odontocetes (toothed whales) because of the importance of the structure in echolocation, but generally these studies use only a single cochlea to represent each species. In this study we compare variation within the cochleae of 18 specimens of P. phocoena with variations in cochlear morphology across 51 other odontocete species. Using both 3D landmark and linear measurement data, we performed Generalised Procrustes and principal component analyses to quantify shape variation. We then quantified intraspecific variation in our sample of P. phocoena by estimating disparity and the coefficient of variation for our 3D and linear data respectively. Finally, to determine whether intraspecific variation may confound the results of studies of interspecific variation, we used multivariate and univariate analyses of variance to test whether variation within the specimens of P. phocoena was significantly lower than that across odontocetes. We found low levels of intraspecific variation in the cochleae of P. phocoena, and that cochlear shape within P. phocoena was significantly less variable than across odontocetes. Although future studies should attempt to use multiple cochleae for every species, our results suggest that using just one cochlea for each species should not strongly influence the conclusions of comparative studies if our results are consistent across Cetacea.

Automatic 3D Landmark Extraction System Based on an Encoder–Decoder Using Fusion of Vision and LiDAR

To provide a realistic environment for remote sensing applications, point clouds are used to realize a three-dimensional (3D) digital world for the user. Motion recognition of objects, e.g., humans, is required to provide realistic experiences in the 3D digital world. To recognize a user’s motions, 3D landmarks are provided by analyzing a 3D point cloud collected through a light detection and ranging (LiDAR) system or a red green blue (RGB) image collected visually. However, manual supervision is required to extract 3D landmarks as to whether they originate from the RGB image or the 3D point cloud. Thus, there is a need for a method for extracting 3D landmarks without manual supervision. Herein, an RGB image and a 3D point cloud are used to extract 3D landmarks. The 3D point cloud is utilized as the relative distance between a LiDAR and a user. Because it cannot contain all information the user’s entire body due to disparities, it cannot generate a dense depth image that provides the boundary of user’s body. Therefore, up-sampling is performed to increase the density of the depth image generated based on the 3D point cloud; the density depends on the 3D point cloud. This paper proposes a system for extracting 3D landmarks using 3D point clouds and RGB images without manual supervision. A depth image provides the boundary of a user’s motion and is generated by using 3D point cloud and RGB image collected by a LiDAR and an RGB camera, respectively. To extract 3D landmarks automatically, an encoder–decoder model is trained with the generated depth images, and the RGB images and 3D landmarks are extracted from these images with the trained encoder model. The method of extracting 3D landmarks using RGB depth (RGBD) images was verified experimentally, and 3D landmarks were extracted to evaluate the user’s motions with RGBD images. In this manner, landmarks could be extracted according to the user’s motions, rather than by extracting them using the RGB images. The depth images generated by the proposed method were 1.832 times denser than the up-sampling-based depth images generated with bilateral filtering.

An Ecomorphological Approach to Craniomandibular Integration in Neotropical Deer

South American cervids have a relatively recent evolutionary history in the Neotropics. Present taxonomical richness includes six genera and 17 species grouped in at least two clades, Blastocerina and Odocoileina. With few exceptions, functional morphology or ecomorphological approaches have not been rigorously applied to the masticatory apparatus of Neotropical deer. In order to understand the relationship between craniomandibular integration and feeding behavior, we used geometric morphometric methods (3D landmarks) to quantify the strength and significance of the correlation between morphology and feeding behavior. Two blocks Partial Least Squares analyses, angular comparison, regression analysis, and independent contrast were performed to explore the patterns of covariation between cranial and mandibular shape and size, and between them and continuous dietary characters. The main variation in shape is related to a gradient from a brachycephalic cranium with a robust mandible in small deer to a dolicocephalic cranium with a gracile mandible in large deer. These shape changes seem to be modeled by a complex interplay of allometric trends and biomechanically significant features related to the proportions of dietary monocotyledon, fruit, or dicotyledonous plant material. We find remarkable convergences in the brocket deer ecomorphotype in the two clades of Neotropical cervids, as well as similar craniomandibular traits between marsh and pampas deer with African mixed feeder bovids related to monocotyledon consumption. These findings lead us to share Radinsky’s interest in convergences in the masticatory apparatus of herbivorous mammals.

A Geometric Morphometric Evaluation of Equid Tooth Shape at Natural Trap Cave, Wyoming

Natural Trap Cave is a sinkhole cave located in Big Horn County in northern Wyoming. The cave preserves many Quaternary taxa, including pollen and large carnivorous and herbivorous mammals such as various felids and ungulates. Many of these taxa went extinct in North America following the late Pleistocene megafaunal extinction. The cave was first excavated in the 1970s and 80s by teams from the University of Kansas and the University of Missouri, and more recently by teams from Des Moines University, The University of Adelaide, and The University of Rochester, along with a wide variety of volunteers. Specimens from this cave have been used to elucidate floral change in the area, disentangle ancient food webs, and extend the hypothesized range for Beringian wolves.Horses are the most common megafaunal group from this site, encompassing two genera: Equus and Haringtonhippus, the “New World stilt‐legged” horse, based on post‐cranial elements and mitochondrial DNA. Some recent studies have shown that horse taxa can be identified by tooth occlusal surface morphology. This study aims to test if isolated equid cheek teeth from Natural Trap Cave can be identified to the genus level, between Equus and Haringtonhippus using geometric morphometrics. 2D landmarks and sliding semi‐landmarks were taken around the periphery of a set of upper cheek teeth, including the areas of greatest curvature at the metastyle, mesostyle, parastyle, and around the protocone and post protoconal valley. Principal component analyses on known specimens do in fact separate Equus and Haringtonhippus, and this difference is statistically sigificant, with the primary difference being the width of the protocone. Additionally, molars and premolars also occupied significantly different areas of morphospace, opening up the possibility of identifying tooth position on unknown specimens as well. With the abundance of isolated horse teeth (either Equus or Haringtonhippus) from Natural Trap Cave, having a reliable means to distinguish between genera will allow us to better study the ecological differences between them and better understand the environment and faunal interactions in late Pleistocene Wyoming.Support or Funding InformationNSF EAR/SGP 1425059 (Natural Trap Cave Revisited: Ancient DNA, Climate and the Megafaunal Extinction) Julie Meachen, PI

Variation in Maxillary Sinus Anatomy: Implications of Ostium Positioning on Health Disparities in Sinusitis

Over 30 million people are diagnosed with sinusitis annually, yet potential anatomical etiologies behind sinus infections remain poorly understood. Paranasal sinus drainage is mediated by mucociliary transport and gravity, but the human orthograde posture and superior positioning of the maxillary sinus (MS) ostia increase reliance on the mucociliary system. Moreover, previous research has suggested that regional differences in MS size and shape may contribute to disparities in sinusitis susceptibility. The purpose of this study was to examine overall MS size and shape, including MS ostium positioning, among three different ancestral groups, to assess potential impacts on drainage and infection risks. Employing CT scans (n=167) of crania from European, East Asian, and Equatorial African ancestries, we collected 28 3D coordinate landmarks per specimen. A total of 34 linear measurements of the MS and surrounding facial features were subsequently calculated and employed in multivariate analyses. MANOVA test results reveal significant differences between regional groups (Wilk’s λ = 0.807, p < 0.0001) and between the sexes (Wilk’s λ = 0.813, p < 0.0001), but no significant interaction between region and sex (Wilk’s λ = 0.971, p = 0.3223). ANOVA and Tukey‐Kramer test results indicate that Asians have both a significantly taller MS (F=15.4, p<0.0001) and a significantly greater distance from the MS floor to the ostium (F=13.5, p<0.0001) compared to Europeans and Africans. Further, a ratio of these two linear variables reveals that the MS floor‐to‐ostium distance constitutes a greater percentage of overall MS height in Asians (62%) than Europeans (60%) or Africans (59%). A canonical variate (CV) analysis of the 28 3D coordinate landmarks provides corroborative results, with CV1 accounting for 70.58% of total variance and separating Asians from Europeans and Africans. Morphologically, CV1 predominantly reflects a lower MS floor in Asians, while the relative superior‐inferior position of the MS ostium within the face appears similar across all ancestries. Cumulatively, these results suggest that both the taller sinus and greater MS floor‐to‐ostium distance in Asians are attributable to a more inferiorly positioned MS floor. As a greater distance from the MS floor to the ostium may lead to increased pressure on the mucociliary clearance, our results suggest that individuals of Asian ancestry may be at a greater risk for chronic sinusitis compared to those of European and African ancestries. Our study thus provides tentative evidence that there may be an anatomical etiology for chronic sinusitis despite an absence of anatomical defect. The increased risk for persistent inflammatory condition is also important since it has been accompanied with subsequent head and neck cancer diagnoses. Additional research into the prevalence of MS sinusitis in these populations is warranted to evaluate possible contributions to health disparities.Support or Funding InformationThis work is partially supported by a grant funded to Dr. Jamboor Vishwanatha by the Cancer Prevention and Research Institute of Texas (Award #: RP170301).

Morphometric Analysis of 3D Soft-Tissue for Sexual Dimorphism in Human Face

Sexual dimorphism in Homo-sapiens is a phenomenon of a direct product of evolution by natural selection where evolutionary forces acted separately on the sexes which brought about the differences in appearance between male and female such as in shape and size. Advances in morphometrics have skyrocketed the rate of research on sex differences in human and other species. However, the current challenges facing 3D in the acquisition of facial data such as lack of homology, insufficient landmarks to characterize the facial shape and complex computational process for facial point digitization require further study in the domain of sex dimorphism. This study investigates sexual dimorphism in the human face with the application of Automatic Homologous Multi-points Warping (AHMW) for 3D facial landmark by building a template mesh as a reference object which is thereby applied to each of the target mesh on Stirling/ESRC dataset containing 101 subjects (male = 47, female = 54). The semi-landmarks are subjected to sliding along tangents to the curves and surfaces until the bending energy between a template and a target form is minimal. Principal Component Analysis (PCA) is used for feature selection and the features are classified using Linear Discriminant Analysis (LDA) with an accuracy of 99.01 % which demonstrates that the method is robust.

Slam algorithm for aruco landmark array based on synchronization optimization

High precision mapping algorithm is the core of two-dimensional(2D) landmark array(the ArUco landmark is used in this paper) localization application. In most of the existing mapping algorithms, the accumulated errors of online methods can not be eliminated, meanwhile, the manual calibration and off-line methods are inefficient and time-consuming. In order to overcome those shortcomings, a real-time simultaneous localization and mapping(SLAM) algorithm for landmark array based on synchronized optimization is proposed in this paper. The proposed algorithm updates and corrects the global map online, and the accumulated errors is optimized based on minimizing the re-projection error of the landmarks ’ vertexes. In order to verify the proposed algorithm, several contrast experiments with other mapping systems are presented. The experimental results show that the proposed algorithm has the advantages of high map precision and small accumulative error.

Variants in the Hippo Signaling Pathway are Associated with Craniofacial Skeletal Form and BMI

Childhood obesity rates in the United States have demonstrated a marked increase since the late 20th century. Current research has suggested that obesity can cause increases in bone density and an acceleration of skeletal growth. While studies have shown that obesity may be associated with altered craniofacial form, the mechanism and associated factors through which this interaction operates remains poorly understood. This study explores a potential link between obesity and craniofacial skeletal form as a function of the Hippo signaling pathway, an important regulator of organ size, tissue development, and craniofacial development.Lateral cephalograms from a sample of n=64 patients between the ages 7 to 17 were obtained from the Midwestern University Multispecialty Clinic. BMI percentile was computed for all children in the study following CDC guidelines (normal weight n=37, overweight n=9, obese n=18). 45 2D landmarks were registered via Generalized Procrustes Analysis (GPA) in order to facilitate a geometric morphometric (GM) analysis. Healthy Eating Index (HEI) scores obtained from Block Food Frequency Questionnaire (FFQ) surveys were used to control for the effects of diet in all subsequent analyses. Shape residuals were submitted to Principal Components Analysis (PCA) and Canonical Variate Analysis (CVA) to identify which aspects of skeletal form differentiate individual phenotypes based on BMI. Finally, associations between these phenotypes and 23 single nucleotide polymorphisms (SNPs) in seven genes within the Hippo signaling pathway were explored.Principal Components (PCs) accounting for at least 1% of facial shape variation were examined in order to determine components that differentiate between normal and obese groups. Based on this, suggestive/significant differences were found in PC 8 (p=0.056) and PC12 (p=0.012) based on BMI category. PC 8 (accounting for 3.6% of the total shape variation) indicates that chin projection, nose length, and mandibular morphology differentiate between normal and obese children. SNPs in TEAD3 (p=0.04) and FAT4 (p = 0.02) were significantly associated with shape variation along PC8. PC 12 (2.6% of the total shape variation) showed significant variation in chin projection and decreased incisor size in the obese group relative to the normal weight group. Additionally, a SNP within LATS2 (p = 0.04) was significantly correlated with shape variation along PC12. Finally, results from the CVA identified two components with CV2 indicating a significant relationship with LEF1 (p= 0.02). CV2 demonstrates increased facial projection in individuals with obesity.Across all analyses, we found a consistent pattern in mandibular length, facial projection, and incisor size that differentiated between normal and obese individuals. SNPs within key genes in the Hippo signaling pathway were associated with these phenotypes, indicating a potential causative relationship. Future studies will explore this relationship further.

Automatic 3D landmarking model using patch-based deep neural networks for CT image of oral and maxillofacial surgery.

Manual landmarking is a time consuming and highly professional work. Although some algorithm-based landmarking methods have been proposed, they lack flexibility and may be susceptible to data diversity. The CT images from 66 patients who underwent oral and maxillofacial surgery (OMS) were landmarked manually in MIMICS. Then the CT slices were exported as images for recreating the 3D volume. The coordinate data of landmarks were further processed in Matlab using a principal component analysis (PCA) method. A patch-based deep neural network model with a three-layer convolutional neural network (CNN) was trained to obtain landmarks from CT images. The evaluating experiment showed that this CNN model could automatically finish landmarking in an average processing time of 37.871 seconds with an average accuracy of 5.785 mm. This study shows a promising potential to relieve the workload of the surgeon and reduces the dependence on human experience for OMS landmarking.

Are geometric morphometric analyses replicable? Evaluating landmark measurement error and its impact on extant and fossil Microtus classification.

Geometric morphometric analyses are frequently employed to quantify biological shape and shape variation. Despite the popularity of this technique, quantification of measurement error in geometric morphometric datasets and its impact on statistical results is seldom assessed in the literature. Here, we evaluate error on 2D landmark coordinate configurations of the lower first molar of five North American Microtus (vole) species. We acquired data from the same specimens several times to quantify error from four data acquisition sources: specimen presentation, imaging devices, interobserver variation, and intraobserver variation. We then evaluated the impact of those errors on linear discriminant analysis‐based classifications of the five species using recent specimens of known species affinity and fossil specimens of unknown species affinity. Results indicate that data acquisition error can be substantial, sometimes explaining >30% of the total variation among datasets. Comparisons of datasets digitized by different individuals exhibit the greatest discrepancies in landmark precision, and comparison of datasets photographed from different presentation angles yields the greatest discrepancies in species classification results. All error sources impact statistical classification to some extent. For example, no two landmark dataset replicates exhibit the same predicted group memberships of recent or fossil specimens. Our findings emphasize the need to mitigate error as much as possible during geometric morphometric data collection. Though the impact of measurement error on statistical fidelity is likely analysis‐specific, we recommend that all geometric morphometric studies standardize specimen imaging equipment, specimen presentations (if analyses are 2D), and landmark digitizers to reduce error and subsequent analytical misinterpretations.

Three-axis measurements with a novel system for 3D plantar foot scanning: iPhone X

Three-dimensional (3D) surface scanning technologies are being used to produce digitized representation of human anatomy parts. The purpose of this study was to determine the agreement between two 3D scanners (Structure iSense and TrueDepth iPhone X) to obtaining anthropometric data from the foot. Fourteen feet from seven voluntary healthy adults (four males and three females) were scanned. 3D landmarks were placed on 1st metatarsal head (1MTH), 5th metatarsal head (5MTH), heel (H) and on the plantar side of the scaphoid tubercle (ST) to acquire measurements in the three space-axes (X, Y and Z). Intraclass correlation coefficient (ICC) > 0.9 was obtained for Structure iSense for the measurements taken in the three axes. ICC > 0.9 was obtained TrueDepth iPhone X for X- and Y-axes and ICC < 0.75 for Z-axis. Low standard error measure (SEM) was obtained in both scanners. The two methods provide moderate to excellent reliability measuring the foot in the three space-axes.

To Hop or Not to Hop? The Answer Is in the Bird Trees.

Birds can use different types of gaits to move on the ground: they either walk, hop, or run. Although velocity can easily explain a preference for running, it remains unclear what drives a bird species to favor hopping over walking. As many hopping birds are relatively small and arboreal, we wanted to test the link between size, arboreality, and hopping ability. First, we carried out ancestral character state reconstructions of size range, hopping ability, and habitat traits on over 1000 species of birds. We found that both hopping ability and arboreality were derived and significantly correlated traits in avian evolution. Second, we tested the influence of hopping ability on the morphology of the lower appendicular skeleton by quantifying the shape differences of the pelvis and the three long bones of the hind limbs in 47 avian species with different habitats and gait preferences. We used geometric morphometrics on 3D landmarks, digitized on micro-computed tomography (micro-CT) and surface scans of the pelvis, femur, tibiotarsus, and tarsometatarsus. Locomotion habits significantly influence the conformation of the pelvis, especially at the origin of hip and knee muscle extensors. Interestingly, habitat, more than locomotion habits, significantly changed tarsometatarsus conformation. The morphology of the distal part of the tarsometatarsus constrains digit orientation, which leads to a greater ability to perch, an advantageous trait in arboreality. The results of this work suggest an arboreal origin of hopping and illuminate the evolution of avian terrestrial locomotion.[Anatomy; avian; gait; leg; lifestyle; pelvis; tree-dwelling.].

Differences in Facial Expressions between Spontaneous and Posed Smiles: Automated Method by Action Units and Three-Dimensional Facial Landmarks.

Research on emotion recognition from facial expressions has found evidence of different muscle movements between genuine and posed smiles. To further confirm discrete movement intensities of each facial segment, we explored differences in facial expressions between spontaneous and posed smiles with three-dimensional facial landmarks. Advanced machine analysis was adopted to measure changes in the dynamics of 68 segmented facial regions. A total of 57 normal adults (19 men, 38 women) who displayed adequate posed and spontaneous facial expressions for happiness were included in the analyses. The results indicate that spontaneous smiles have higher intensities for upper face than lower face. On the other hand, posed smiles showed higher intensities in the lower part of the face. Furthermore, the 3D facial landmark technique revealed that the left eyebrow displayed stronger intensity during spontaneous smiles than the right eyebrow. These findings suggest a potential application of landmark based emotion recognition that spontaneous smiles can be distinguished from posed smiles via measuring relative intensities between the upper and lower face with a focus on left-sided asymmetry in the upper region.

Epiplastral and geographic variation in &lt;em&gt;Echmatemys&lt;/em&gt;, a geoemydid turtle from the Eocene of North America: A multi-tiered analysis of epiplastral shape complexity

Author(s): Smith, Heather F.; Jager, Daniel; Hutchison, J. Howard; Adrian, Brent; Townsend, K.E. Beth | Abstract: Numerous geoemydid turtle fossils from the extinct genus Echmatemys have been recovered from the middle Eocene Uinta Formation, Uinta Basin, Utah over the past several decades. Here, we tested whether co-occurring Uintan species Echmatemys callopyge and E. uintensis can be reliably differentiated based on epiplastral morphology, and whether their geospatial distributions overlapped significantly. The geographic spatial and stratigraphic distributions of Uinta Basin E. callopyge and E. uintensis specimens were compared using ArcGIS and analysis of variance (ANOVA). The analysis revealed overlapping geographic distributions of these two species, and no significant differences in stratigraphic dispersal. This finding of extensive geospatial overlap between the two Uintan Echmatemys species highlights the need for accurate taxonomic identification, such as the gular scale morphology validated here. In addition, we sought to address a methodological question regarding the relative efficacy of data complexity in this context. Using epiplastra from three additional Eocene species of Echmatemys, we employed hierarchical analyses of increasing data complexity, from standard linear dimensions to 2D geometric morphometrics to 3D laser scans, to determine the degree to which data complexity contributes to taxonomic assessments within this genus. Uintan species E. callopyge and E. uintensis were found to differ significantly in epiplastral shape as captured by all three categories of data. These findings verify that these two co-occurring species can be differentiated consistently using the shape of the gular scale, and that the use of geometric morphometrics can improve identification of fragmentary specimens. Among the non-Uintan species, dorsal and ventral 2D landmark data reliably differentiated among species, but the linear dimensions were less useful.

Morphological consequences of artificial cranial deformation: Modularity and integration.

The cranium is an anatomically complex structure. One source of its complexity is due to its modular organization. Cranial modules are distinct and partially independent units that interact substantially during ontogeny thus generating morphological integration. Artificial Cranial Deformation (ACD) occurs when the human skull is intentionally deformed, through the use of different deforming devices applied to the head while it is developing. Hence, ACD provides an interesting example to assess the degree to which biomechanical perturbations of the developing neurocranium impact on the degree of morphological integration in the skull as a whole. The main objective of this study was to assess how ACD affects the morphological integration of the skull. This was accomplished by comparing a sample of non-deformed crania and two sets of deformed crania (i.e. antero-posterior and oblique). Both developmental and static modularity and integration were assessed through Generalized Procrustes Analysis by considering the symmetric and asymmetric components of variation in adults, using 3D landmark coordinates as raw data. The presence of two developmental modules (i.e. viscero and neurocranium) in the skull was tested. Then, in order to understand how ACD affects morphological integration, the covariation pattern between the neuro and viscerocranium was examined in antero-posterior, oblique and non-deformed cranial categories using Partial Least-Squares. The main objective of this study was to assess how ACD affects the morphological integration of the skull. This was accomplished by comparing a sample of deformed (i.e. antero-posterior and oblique) and non-deformed crania. Hence, differences in integration patterns were compared between groups. The obtained results support the modular organization of the human skull in the two analyzed modules. The integration analyses show that the oblique ACD style differentially affects the static morphological integration of the skull by increasing the covariance between neuro and viscerocranium in a more constrained way than in antero-posterior and non-deformed skulls. In addition, the antero-posterior ACD style seems to affect the developmental integration of the skull by directing the covariation pattern in a more defined manner as compared to the other cranial categories.

Landmark-based homologous multi-point warping approach to 3D facial recognition using multiple datasets.

Over the years, neuroscientists and psychophysicists have been asking whether data acquisition for facial analysis should be performed holistically or with local feature analysis. This has led to various advanced methods of face recognition being proposed, and especially techniques using facial landmarks. The current facial landmark methods in 3D involve a mathematically complex and time-consuming workflow involving semi-landmark sliding tasks. This paper proposes a homologous multi-point warping for 3D facial landmarking, which is verified experimentally on each of the target objects in a given dataset using 500 landmarks (16 anatomical fixed points and 484 sliding semi-landmarks). This is achieved by building a template mesh as a reference object and applying this template to each of the targets in three datasets using an artificial deformation approach. The semi-landmarks are subjected to sliding along tangents to the curves or surfaces until the bending energy between a template and a target form is minimal. The results indicate that our method can be used to investigate shape variation for multiple datasets when implemented on three databases (Stirling, FRGC and Bosphorus).

Three-dimensional cone beam computed tomography analysis of temporomandibular joint response to the Twin-block functional appliance.

ObjectiveTo propose a three-dimensional (3D) method for evaluating temporomandibular joint (TMJ) changes during Twin-block treatment.MethodsSeventeen patients with Class II division 1 malocclusion treated using Twin-block and nine untreated patients with a similar malocclusion were included in this research. We collected their cone beam computed tomography (CBCT) data from before and 8 months after treatment. Segmentations were constructed using ITK-SNAP. Condylar volume and superficial area were measured using 3D Slicer. The 3D landmarks were identified on CBCT images by using Dolphin software to assess the condylar positional relationship. 3D models of the mandible and glenoid fossa of the patients were constructed and registered via voxel-based superimposition using 3D Slicer. Thereafter, skeletal changes could be visualized using 3DMeshMetric in any direction of the superimposition on a color-coded map. All the superimpositions were measured using the same scale on the distance color-coded map, in which red color represents overgrowth and blue color represents resorption.ResultsSignificant differences were observed in condylar volume, superficial area, and condylar position in both groups after 8 months. Compared with the control group (CG), the Twin-block group exhibited more obvious condyle-fossa modifications and joint positional changes. Moreover, on the color-coded map, more obvious condyle-fossa modifications could be observed in the posterior and superior directions in the Twin-block group than in the CG.ConclusionsWe successfully established a 3D method for measuring and evaluating TMJ changes caused by Twin-block treatment. The treatment produced a larger condylar size and caused condylar positional changes.