Compact Bone (compact + bone)

Distribution by Scientific Domains


Selected Abstracts


Automatic Conversion of Mesh Animations into Skeleton-based Animations

COMPUTER GRAPHICS FORUM, Issue 2 2008
Edilson De Aguiar
Abstract Recently, it has become increasingly popular to represent animations not by means of a classical skeleton-based model, but in the form of deforming mesh sequences. The reason for this new trend is that novel mesh deformation methods as well as new surface based scene capture techniques offer a great level of flexibility during animation creation. Unfortunately, the resulting scene representation is less compact than skeletal ones and there is not yet a rich toolbox available which enables easy post-processing and modification of mesh animations. To bridge this gap between the mesh-based and the skeletal paradigm, we propose a new method that automatically extracts a plausible kinematic skeleton, skeletal motion parameters, as well as surface skinning weights from arbitrary mesh animations. By this means, deforming mesh sequences can be fully-automatically transformed into fullyrigged virtual subjects. The original input can then be quickly rendered based on the new compact bone and skin representation, and it can be easily modified using the full repertoire of already existing animation tools. [source]


Osteoderm morphology in recent and fossil euphractine xenarthrans

ACTA ZOOLOGICA, Issue 4 2009
C. M. Krmpotic
Abstract The presence of osteoderms within the integument, forming a carapace, is one of the most distinctive features of armadillos with the external morphology of these elements forming the basis of most systematic schemes. This is especially true for fossil taxa, where these elements are most frequent in the palaeontological record. A detailed study of osteoderms from the cephalic shield and different regions of the dorsal armour of Chaetophractus villosus (Euphractinae, Xenarthra) was made and compared to those of the extant genus Dasypus (Dasypodinae, Xenarthra), and the extinct genus ,Eutatus. Three distinct histological zones were recognized: outer and inner zones are thin, formed by regular compact bone, the middle zone is thicker, with large cavities that contain mainly adipose tissue, hair follicles, and sweat and sebaceous glands. The internal structure of ,Eutatus (also a member of Euphractinae) osteoderms is close to that of C. villosus, consistent with the notion that these taxa are phylogenetically closely related. In contrast, Dasypus shows marked differences. Dasypus shows hair follicles associated with both gland types (sweat and sebaceous) and connected to foramina on the external surface. Although not observed in adult C. villosus, it has been documented during embryonic development, only to atrophy later in ontogeny. Furthermore, the presence of red bone marrow is rare in C. villosus, but widespread in Dasypus novemcinctus osteoderms. These results suggest an early split of both subfamilies and support the hypothesis that the Euphractinae are more derived than the Dasypodinae. [source]


Long-term ovariectomy decreases ovine compact bone viscoelasticity

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2005
C. M. Les
Abstract Changes in bone mineral density associated with estrogen depletion in humans do not account for all of the associated change in fracture risk, and it is possible that some of this variation may lie in changes of other aspects of bone quality. The purpose of this study was to investigate changes in viscoelastic behavior of compact bone that may be associated with estrogen depletion. Changes in compact bone viscoelastic properties associated with three years of ovariectomy were investigated with dynamic mechanical analysis (low-amplitude 3-point bending at frequencies of 1,20 Hz) using beams milled from the diaphysis of the ovine radius. The viscoelastic storage modulus was significantly (5.2%) lower at the higher frequencies for the ovariectomized animals. The general anatomic variation in storage modulus, in which cranial sectors had higher values than caudal sectors, did not change with ovariectomy. The loss tangent (tan ,, a measure of damping) was also greatly decreased (up to 83%) at high frequencies in the ovariectomized animals. Anatomic variation in tan , at low (6,12 Hz) frequencies (cranial and caudal sectors having higher values than lateral or medial sectors) was enhanced with ovariectomy. Changes in viscoelastic properties associated with long term estrogen depletion could be responsible for a significant reduction in the toughness or strength of a bone without concomitant changes in screening modalities used to evaluate bone quality (e.g., DXA, QCT, QUA). © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]


Histological evaluation on bone regeneration of dental implant placement sites grafted with a self-setting ,-tricalcium phosphate cement

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2008
Masayoshi Nakadate
Abstract This study aimed to evaluate the histological characteristics of the new bone formed at dental implant placement sites concomitantly grafted with a self-setting tricalcium phosphate cement (BIOPEX-R®). Standardized defects were created adjacent to the implants in maxillae of 4-week-old male Wistar rats, and were concomitantly filled with BIOPEX-R®. Osteogenesis was examined in two sites of extreme clinical relevance: (1) the BIOPEX-R®-grafted surface corresponding to the previous alveolar ridge (alveolar ridge area), and (2) the interface between the grafting material and implants (interface area). At the alveolar ridge area, many tartrate-resistant acid phosphatase (TRAPase)-reactive osteoclasts had accumulated on the BIOPEX-R® surface and were shown to migrate toward the implant. After that, alkaline phosphatase (ALPase)-positive osteoblasts deposited new bone matrix, demonstrating their coupling with osteoclasts. On the other hand, the interface area showed several osteoclasts initially invading the narrow gap between the implant and graft material. Again, ALPase-positive osteoblasts were shown to couple with osteoclasts, having deposited new bone matrix after bone resorption. Transmission electron microscopic observations revealed direct contact between the implant and the new bone at the interface area, although few thin cells could still be identified. At both the alveolar ridge and the interface areas, newly formed bone resembled compact bone histologically. Also, concentrations of Ca, P, and Mg were much alike with those of the preexistent cortical bone. In summary, when dental implant placement and grafting with BIOPEX-R® are done concomitantly, the result is a new bone that resembles compact bone, an ideal achievement in reconstructive procedures for dental implantology. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source]


Opacity and Lucency Sign of the Seventh Lumbar Vertebra in Dogs

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2010
S. Kneissl
With 2 figures Summary A curvilinear opacity of the seventh vertebral arch and an adjacent focal lucency of the seventh lumbar vertebral body were incidentally noted in routine radiographs. The aim of this study was to analyze this radiographic absorption pattern using a sample of 51 dogs. Images of the bony surface of three macerated lumbosacral junctions were compared to their laterolateral radiographs and computed tomographic (CT) scans. Additional 48 lateral radiographic projections were reviewed for presence or absence of L7 opacity and lucency, length of the L6 and L7 vertebral bodies, vertebral disc disease, osteochondrosis, or spondylosis. Retrieved data were compiled and statistically analyzed. Radiographs and CT scans of the macerated bones revealed that the L7 pedicle had thickened layers of compact bone and the adjacent vertebral notch varying depth and extension. Superimposition of the pedicle on the vertebral body resulted in a curvilinear opacity (L7 opacity), the vertebral notch caused the focal lucency (L7 lucency). These findings were present in 69% of the reviewed radiographs and were found to be significantly associated with L6,L7 length ratios of less than 0.86 (P = 0.003). It is hypothesized that the changes correspond with normal anatomic morphology of the seventh lumbar vertebra plus adaptive bone remodelling. The importance of this study is that it could help avoid misinterpretation of this appearance as a pathologic condition. [source]


Anatomic site evaluation of the palatal bone for temporary orthodontic anchorage devices

CLINICAL ORAL IMPLANTS RESEARCH, Issue 7 2008
Heinrich Wehrbein
Abstract: Objectives: The aim of the present study was to assess the micromorphologic characteristics of the palatal bone from an implantologic standpoint. Materials and Methods: The material consisted of tissue blocks of autopsy material from 22 subjects (18 males, three females) between 18 and 63 years of age. The specimens comprised the anterior median palatal region from 5 to 10 mm behind the incisive foramen. They were prepared in the transversal plane according to ground thin-section technology. The midpalatal area as well as an area of 3 mm bilateral to the midline were assessed, and a classification of quantitative palatal bone availability was developed. Results: The findings could be divided into three classes: (1) class I palatal bone consists almost of compact bone; (2) class II cortical bone layer on oral and nasal sides of palate, broad compact bone in the suture area (,3 mm), loose trabecular bone lateral to the suture area; and (3) class III cortical bone on oral and nasal side, thin compact bone in the suture area (<3 mm) and loose-structured trabecular bone lateral to the suture area. In most sections (72.7%), class I characteristics were found (16 subjects). 18.2% of sections were assigned to class II (four subjects) and only 9.1% of sections were assigned to class III (two subjects). Conclusion: These results document that in most cases a good primary stability of temporary orthodontic anchorage devices should be achieved in the midpalatal and paramedian area of the anterior palate, as the bone quantity available is high. [source]


Bone augmentation by onlay implant using recombinant human BMP-2 and collagen on adult rat skull without periosteum

CLINICAL ORAL IMPLANTS RESEARCH, Issue 4 2000
Masaru Murata
The purpose of this study was to determine whether bone augmentation could be obtained by the composite of recombinant human bone morphogenetic protein-2 (rhBMP-2) and bioabsorbable atelocollagen when the periosteum was resected, and to compare the efficacy of the rhBMP-2/collagen implant and the collagen alone implant. The onlay implant was inserted into the space between the elevated galea aponeurotica and the skull without the periosteum of 10-month-old rats. The rhBMP-2/collagen implant resulted in osteoblasts differentiation under the galea at 1 week and active bone formation without a prior formation of cartilage. At 4 weeks, the bony trabeculae were interconnected and connected directly with the compact bone of the skull. Histomorphometric analysis at 4 weeks demonstrated that the rhBMP-2/collagen implant showed 92.5% in the volume of bone tissue, whereas the collagen alone showed 0%. The implanted collagen was gradually replaced by bone tissue in the presence of rhBMP-2. Our present results indicate that rhBMP-2 stimulates undifferentiated mesenchymal cells in the galea overlying the implant to proliferate and differentiate directly into osteoblasts on the carrier collagen fibers. The collagen matrix was stably placed on the skull and suitable as a substitute for rhBMP-2. The rhBMP-2/collagen onlay implant might be clinically applicable for bone augmentation even under the condition without the periosteum. [source]


Examining criteria for identifying and differentiating fossil faunal assemblages accumulated by hyenas and hominins using extant hyenid accumulations

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1 2010
B. F. Kuhn
Abstract Numerous authors have put forth criteria for distinguishing between assemblages collected by hyenas and hominins. Of the seven most recognised criteria used to distinguish hyenid from hominin assemblages, it has recently been suggested that four be rejected and three retained. The four rejected criteria are: an excessive proportion of horns and horn cores in hyena accumulated assemblages; the absence of small, hard, compact bones; mortality profiles; and the ratio of cranial bones to postcranial bones. The three criteria previous researchers suggested be retained are: a carnivore MNI ratio of ,20%; an abundance of cylinder fragments; and hyena-inflicted damage upon the bones. In this examination of over 27,000 faunal remains associated with all three species of extant bone-collecting hyenids from four countries and two continents, six of the seven previously established criteria and reconsiderations of criteria have been evaluated. The results of the present study indicate that of the six criteria examined, none, as written, are indicative of hyenid activity on bone assemblages of unknown origin. Copyright © 2008 John Wiley & Sons, Ltd. [source]