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Human Mandibles (human + mandible)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

Prenatal craniofacial morphogenesis: four-dimensional visualization of morphogenetic processes

ORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 2003
RJ Radlanski
Structured Abstract Author , Radlanski RJ Objectives , Basic research concerning craniofacial development presently runs along two pathways, namely the molecular and the morphometric. This gap needs to be bridged. Design , Using histological serial sections of human fetuses computer-aided three-dimensional reconstructions were made (Software Analysis, SIS) with special focus given to all anatomical structures of the orofacial region of the growing head. Results , All reconstructions can be viewed from any rotation and they are available for virtual dissection according to anatomical rules. As an example, the prenatal development of the human mandible with the formation of the mental foramen therein is described. Furthermore, the spatial arrangement of bone, cartilage and nerves is presented in three dimensions in different developmental stages. The interaction of tissues with possible morphogenetic interaction is discussed. Conclusions , This work serves as a reference system for prenatal development in comparison with pathological development. [source]

An analysis of secular change in the human mandible over the last century

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009
D. C. Martin
In light of several recent investigations that have identified notable secular change in cranial size and morphology over the last century, the present study addresses its possible effects in the mandible in U.S. populations. Standard measurements of 407 mandibles from the Terry (Smithsonian) and Hamann-Todd (Cleveland Museum of Natural History) Collections, which are primarily composed of individuals living in the early 20th century, were compared with those of 595 mandibles from the Forensic Anthropology Database (Tennessee), which is primarily composed of individuals living from the later part of the century. The t -tests between the two temporally-different samples by sex and race showed statistically significant decreases in mandibular body width and bigonial breadth as well as significant increases in mandibular body length in nearly all subgroups. White males showed the greatest amount of change, and Black females, the least. Overall, these findings support the conclusion that the mandible is transforming into a longer, narrower, more gracile bone, paralleling many of the morphological shifts seen in the cranium. Factors involved likely include changes in diet, medical care, and dental practices. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source]

Regional, ontogenetic, and sex-related variations in elastic properties of cortical bone in baboon mandibles

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2010
Qian Wang
Abstract Understanding the mechanical features of cortical bone and their changes with growth and adaptation to function plays an important role in our ability to interpret the morphology and evolution of craniofacial skeletons. We assessed the elastic properties of cortical bone of juvenile and adult baboon mandibles using ultrasonic techniques. Results showed that, overall, cortical bone from baboon mandibles could be modeled as an orthotropic elastic solid. There were significant differences in the directions of maximum stiffness, thickness, density, and elastic stiffness among different functional areas, indicating regional adaptations. After maturity, the cortical bone becomes thicker, denser, and stiffer, but less anisotropic. There were differences in elastic properties of the corpus and ramus between male and female mandibles which are not observed in human mandibles. There were correlations between cortical thicknesses and densities, between bone elastic properties and microstructural configuration, and between the directions of maximum stiffness and bone anatomical axes in some areas. The relationships between bone extrinsic and intrinsic properties bring us insights into the integration of form and function in craniofacial skeletons and suggest that we need to consider both macroscopic form, microstructural variation, and the material properties of bone matrix when studying the functional properties and adaptive nature of the craniofacial skeleton in primates. The differences between baboon and human mandibles is at variance to the pattern of differences in crania, suggesting differences in bone adaption to varying skeletal geometries and loading regimes at both phylogenetic and ontogenetic levels. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source]

Size variation in early human mandibles and molars from Klasies River, South Africa: Comparison with other middle and late Pleistocene assemblages and with modern humans,

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009
Danielle F. Royer
Abstract Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best-represented elements at the site, namely the mandibular corpora and M2s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skh,l, Dolní V,stonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skh,l, Dolní V,stonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

Radiological trace of mandibular primary growth center in postnatal human mandibles

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 12 2006
Young Joon Lee
Abstract The mandibular primary growth center (MdPGC) of human fetus was conspicuously defined in the soft X-ray view of fetal mandibles. As the peripheral adaptive growth of mandible advances during the postnatal period, the MdPGC image became overshadowed by condensed cortical bones in soft X-ray view. In this study, we traced a sclerotic sequela of MdPGC during the postnatal period. Panoramic radiograms of 200 adults and soft X-ray views of 30 dried adult mandibles were analyzed by statistical methods. The former clearly showed an MdPGC below the middle portion of apices of canine and first premolar, which was distinguishable from mental foramen, and the latter also showed the MdPGC at the same area as a radiating and condensed radiopaque image, measuring 0.5,1.0 cm in diameter. This MdPGC position was seldom changed in the elderly people, even in the edentulous mandibles. Additionally, in the radiological examination, the benign tumors including odontogenic cysts hardly involved the MdPGC, while the malignant tumors of both primary and metastatic cancer frequently destroyed the MdPGC. Anat Rec Part A, 2006. © 2006 Wiley,Liss, Inc. [source]