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Bosnian Journal of Basic Medical... Feb 2016Availability of adequate bone structure for dental implants is still a problem in dentistry. Alloplastic grafts, which promote bone regeneration, are used as bone...
Availability of adequate bone structure for dental implants is still a problem in dentistry. Alloplastic grafts, which promote bone regeneration, are used as bone substitutes in orthopedic and oral surgical procedures. The aim of this study was to evaluate the radiopacity of three different synthetic bone grafts in rabbit calvaria, over 3 months, using cone beam computed tomography (CBCT). Four critical-size defects were made on the calvaria of 11 rabbits. The lesions were classified into three groups according to the alloplastic grafts they received: Osteon® 70/30, Osteon collagen®, and Osteon II® groups. The fourth group received blood clot, and served as a control. The bone samples were collected and analyzed with CBCT after the 1st, 2nd, and 3rd month. One month after surgery, the lesions that received Osteon® 70/30 and Osteon collagen® grafts showed the highest radiopacity compared to the lesions with Osteon II® and blood clot. After the 2nd month, the radiopacity values between the three groups that received the grafts were more similar compared to the group with blood clot. After the 3rd month, the lesions with Osteon® 70/30 graft showed the highest radiopacity values, followed by Osteon collagen® and Osteon II® groups. The group that received blood clot showed the lowest radiopacity values. In conclusion, the grafts used in this study had higher radiopacity values compared to blood clot. Among the grafts used, the Osteon® 70/30 graft showed the highest radiopacity values in the 3-month period.
Topics: Acrylic Resins; Animals; Blood Coagulation; Bone Regeneration; Bone Substitutes; Bone Transplantation; Collagen; Cone-Beam Computed Tomography; Haversian System; Humans; Rabbits; Recombinant Proteins; Skull
PubMed: 27968706
DOI: 10.17305/bjbms.2016.1482 -
Bone Reports Dec 2022The differences in bone nanomechanical properties between cortical (Ct) and trabecular (Tb) bone remain uncertain, whereas knowing the respective contribution of each...
The differences in bone nanomechanical properties between cortical (Ct) and trabecular (Tb) bone remain uncertain, whereas knowing the respective contribution of each compartment is critical to understand the origin of bone strength. Our purpose was to compare bone mechanical and intrinsic properties of Ct and Tb compartments, at the bone structural unit (BSU) level, in iliac bone taken from a homogeneous untreated human population. Among 60 PMMA-embedded transiliac bone biopsies from untreated postmenopausal osteoporotic women (64 ± 7 year-old), >2000 BSUs were analysed by nanoindentation in physiological wet conditions [indentation modulus (elasticity), hardness, dissipated energy], by Fourier transform infrared (FTIRM) and Raman microspectroscopy (mineral and organic characteristics), and by X-ray microradiography (degree of mineralization of bone, DMB). BSUs were categorized based on tissue age, osteonal (Ost) and interstitial (Int) tissues location and bone compartments (Ct and Tb). Indentation modulus was higher in Ct than in Tb BSUs, both in Ost and Int. dissipated energy was higher in Ct than Tb, in Int BSUs. Hardness was not different between Ct and Tb BSUs. In Ost or Int BSUs, mineral maturity (conversion of non-apatitic into apatitic phosphates) was higher in Ct than in Tb, as well as for collagen maturity (Ost). Mineral content assessed as mineral/matrix (FTIRM and Raman) or as DMB, was lower in Ct than in Tb. Crystallinity (FTIRM) was similar in BSUs from Ct and Tb, and slightly lower in Ct than in Tb when measured by Raman, indicating that the crystal size/perfection was quite similar between Ct and Tb BSUs. The differences found between Ost and Int tissues were much higher than the difference found between Ct and Tb for all those bone material properties. Multiple regression analysis showed that Indentation modulus and dissipated energy were mainly explained by mineral maturity in Ct and by collagen maturity in Tb, and hardness by mineral content in both Ct and Tb. In conclusion, in untreated human iliac bone, Ct and Tb BSUs exhibit different characteristics. Ct BSUs have higher indentation modulus, dissipated energy (Int), mineral and organic maturities than Tb BSUs, without difference in hardness. Although those differences are relatively small compared to those found between Ost and Int BSUs, they may influence bone strength at macroscale.
PubMed: 36213624
DOI: 10.1016/j.bonr.2022.101623 -
Pathology Oncology Research : POR 2000Blood formation by pluripotent stem cells and their progeny is thought to be regulated by receptor-ligand interactions between cell-substrate, cell-cell and cell-matrix... (Review)
Review
Blood formation by pluripotent stem cells and their progeny is thought to be regulated by receptor-ligand interactions between cell-substrate, cell-cell and cell-matrix in the bone marrow. Primitive stem cells form progenitors and, in their turn, these give rise to haemopoietic progeny which are more specifically committed in that they can form progressively fewer types of blood cells. Recently we have established that direct cell-cell communication via gap junctions may be part of this regulatory system. Connexin43 gap junctions metabolically couple the three dimensional meshwork of bone marrow stromal cells to form a functional syncytium in which some blood-forming cells are also coupled. The expression of gap junctions in the bone marrow is markedly upregulated when there is an urgent and substantial demand for blood-formation; for example, following cytotoxic injury after 5-fluorouracil or irradiation; or during neonatal blood-formation and in the epiphysis of growing bones. Chemical blockade of gap junctions blocks blood-formation in long-term cultures but is reversible after the blockade has been relieved. This short review highlights briefly the known regulatory mechanisms of blood-formation with especial attention to gap junctional communication.
Topics: Animals; Cell Communication; Connexin 43; Extracellular Matrix; Gap Junctions; Haversian System; Hematopoiesis; Hematopoietic Cell Growth Factors; Humans; Integrins; Mice; Up-Regulation
PubMed: 11173655
DOI: 10.1007/BF03187326 -
International Journal of Legal Medicine Sep 2022Numerous intrinsic and extrinsic factors influence bone remodelling rates and have shown to affect the accuracy of histological aging methods. The present study...
Numerous intrinsic and extrinsic factors influence bone remodelling rates and have shown to affect the accuracy of histological aging methods. The present study investigates the rib cortex from two Mediterranean skeletal collections exploring the development of population-specific standards for histomorphometric age-at-death estimation. Eighty-eight standard ribs from two samples, Cretans and Greek-Cypriots, were processed histologically. Thirteen raw and composite histomorphometric parameters were assessed and observer error tested. The correlation between age and the parameters and the differences between sex and population subsamples were explored through group comparisons and analysis of covariance. General linear models assessed through data fit indicators and cross-validation were generated from the total dataset, and by sex and population subsamples. Most of the histological variables showed a statistically significant correlation with age with some differences observed by sex and by sample. From the twelve models generated, the optimal model for the whole sample included osteon population density (OPD), osteon perimeter, and osteon circularity producing an error of 10.71 years. When sex and samples were separated, the best model selected included OPD and osteon perimeter producing an error of 8.07 years for Greek-Cypriots. This research demonstrates the feasibility of quantitative bone histology to estimate age, obtaining errors rates in accordance with macroscopic ageing techniques. Sex and sample population differences need further investigation and inter-population variation in remodelling rates is suggested. Moreover, this study contributes to the creation of population-specific standards for Cretans and Greek-Cypriots.
Topics: Age Determination by Skeleton; Aging; Bone Remodeling; Haversian System; Humans; Linear Models; Ribs
PubMed: 35394177
DOI: 10.1007/s00414-022-02812-2 -
Materials (Basel, Switzerland) Mar 2019In this work we present a novel algorithm for generating in-silico biomimetic models of a cortical bone microstructure towards manufacturing biomimetic bone via additive...
In this work we present a novel algorithm for generating in-silico biomimetic models of a cortical bone microstructure towards manufacturing biomimetic bone via additive manufacturing. The software provides a tool for physicians or biomedical engineers to develop models of cortical bone that include the inherent complexity of the microstructure. The correspondence of the produced virtual prototypes with natural bone tissue was assessed experimentally employing Digital Light Processing (DLP) of a thermoset polymer resin to recreate healthy and osteoporotic bone tissue microstructure. The proposed tool was successfully implemented to develop cortical bone structure based on osteon density, cement line thickness, and the Haversian and Volkmann channels to produce a user-designated bone porosity that matches within values reported from literature for these types of tissues. Characterization of the specimens using a Scanning Electron Microscopy with Focused Ion Beam (SEM/FIB) and Computer Tomography (CT) revealed that the manufacturability of intricated virtual prototype is possible for scaled-up versions of the tissue. Modeling based on the density, inclination and size range of the osteon and Haversian and Volkmann´s canals granted the development of a dynamic in-silico porosity (13.37⁻21.49%) that matches with models of healthy and osteoporotic bone. Correspondence of the designed porosity with the manufactured assessment (5.79⁻16.16%) shows that the introduced methodology is a step towards the development of more refined and lifelike porous structures such as cortical bone. Further research is required for validation of the proposed methodology model of the real bone tissue and as a patient-specific customization tool of synthetic bone.
PubMed: 30893894
DOI: 10.3390/ma12060913 -
Journal of Anatomy Oct 2011Cortical bone histology has been the subject of scientific inquiry since the advent of the earliest microscopes. Histology - literally the study of tissue - is a field...
Cortical bone histology has been the subject of scientific inquiry since the advent of the earliest microscopes. Histology - literally the study of tissue - is a field nearly synonymous with 2D thin sections. That said, progressive developments in high-resolution X-ray imaging are enabling 3D visualization to reach ever smaller structures. Micro-computed tomography (micro-CT), employing conventional X-ray sources, has become the gold standard for 3D analysis of trabecular bone and is capable of detecting the structure of vascular (osteonal) porosity in cortical bone. To date, however, direct 3D visualization of secondary osteons has eluded micro-CT based upon absorption-derived contrast. Synchrotron radiation micro-CT, through greater image quality, resolution and alternative contrast mechanisms (e.g. phase contrast), holds great potential for non-destructive 3D visualization of secondary osteons. Our objective was to demonstrate this potential and to discuss areas of bone research that can be advanced through the application of this approach. We imaged human mid-femoral cortical bone specimens derived from a 20-year-old male (Melbourne Femur Collection) at the Advanced Photon Source synchrotron (Chicago, IL, USA) using the 2BM beam line. A 60-mm distance between the target and the detector was employed to enhance visualization of internal structures through propagation phase contrast. Scan times were 1 h and images were acquired with 1.4-μm nominal isotropic resolution. Computer-aided manual segmentation and volumetric 3D rendering were employed to visualize secondary osteons and porous structures, respectively. Osteonal borders were evident via two contrast mechanisms. First, relatively new (hypomineralized) osteons were evident due to differences in X-ray attenuation relative to the surrounding bone. Second, osteon boundaries (cement lines) were delineated by phase contrast. Phase contrast also enabled the detection of soft tissue remnants within the vascular pores. The ability to discern osteon boundaries in conjunction with vascular and cellular porosity revealed a number of secondary osteon morphologies and provided a unique 3D perspective of the superimposition of secondary osteons on existing structures. Improvements in resolution and optimization of the propagation phase contrast promise to provide further improvements in structural detail in the future.
Topics: Femur; Haversian System; Humans; Imaging, Three-Dimensional; Male; Synchrotrons; X-Ray Microtomography; Young Adult
PubMed: 21644972
DOI: 10.1111/j.1469-7580.2011.01398.x -
Journal of Anatomy Feb 2013A casting technique with methyl-methacrylate (MMA) was applied to the study of the osteon lacunar-canalicular network of human and rabbit cortical bone. The MMA monomer...
A casting technique with methyl-methacrylate (MMA) was applied to the study of the osteon lacunar-canalicular network of human and rabbit cortical bone. The MMA monomer infiltration inside the vascular canals and from these into the lacunar-canalicular system was driven by capillarity, helped by evaporation and the resulting negative pressure in a system of small pipes. There was uniform, centrifugal penetration of the resin inside some osteons, but this was limited to a depth of four to five layers of lacunae. Moreover, not all of the osteon population was infiltrated. This failure can be the result of one of two factors: the incomplete removal of organic debris from the canal and canalicular systems, and lack of drainage at the osteon external border. These data suggest that each secondary osteon is a closed system with a peripheral barrier (represented by the reversal line). As the resin advances into the osteon, the air contained inside the canalicula is compressed and its pressure increases until infiltration is stopped. The casts gave a reliable visualization of the lacunar shape, position and connections between the lacunae without the need for manipulations such as cutting or sawing. Two systems of canalicula could be distinguished, the equatorial, which connected the lacunae (therefore the osteocytes) lying on the same concentric level, and the radial, which established connections between different levels. The equatorial canalicula radiated from the lacunar border forming ramifications on a planar surface around the lacuna, whereas the radial canalicula had a predominantly straight direction perpendicular to the equatorial plane. The mean length of the radial canalicula was 40.12 ± 10.26 μm in rabbits and 38.4 ± 7.35 μm in human osteons; their mean diameter was 174.4 ± 71.12 nm and 195.7 ± 79.58 nm, respectively. The mean equatorial canalicula diameter was 237 ± 66.04 nm in rabbit and 249.7 ± 73.78 nm in human bones, both significantly larger (P < 0.001) than the radial. There were no significant differences between the two species. The lacunar surface measured on the equatorial plane was higher in rabbit than in man, but the difference was not statistically significant. The cast of the lacunar-canalicular network obtained with the reported technique allows a direct, 3-D representation of the system architecture and illustrates how the connections between osteocytes are organized. The comparison with models derived by the assumption of the role of hydraulic conductance and other mechanistic functions provides descriptive, morphological data to the ongoing discussion on the Haversian system biology.
Topics: Acrylic Resins; Animals; Femur; Humans; Male; Microscopy, Electron, Scanning; Models, Anatomic; Osteocytes; Rabbits; Replica Techniques; Tibia
PubMed: 23082756
DOI: 10.1111/joa.12004 -
Journal of Structural Biology Sep 2016The macro- and micro-features of bone can be assessed by using imaging methods. However, nano- and molecular features require more detailed characterization, such as use...
The macro- and micro-features of bone can be assessed by using imaging methods. However, nano- and molecular features require more detailed characterization, such as use of e.g., vibrational spectroscopy and X-ray scattering. Nano- and molecular features also affect the mechanical competence of bone tissue. The aim of the present study was to reveal the effects of mineralization and its alterations on the mineral crystal scale, by investigating the spatial variation of molecular composition and mineral crystal structure across the cross-section of femur diaphyses in young rats, and healthy and osteoporotic mature rats (N=5). Fourier transform infrared spectroscopy and scanning small- and wide-angle X-ray scattering (SAXS/WAXS) techniques with high spatial resolution were used at identical locations over the whole cross-section. This allowed quantification of point-by-point information about the spatial distribution of mineral crystal volume. All measured parameters (crystal dimensions, degree of orientation and predominant orientation) varied across the cortex. Specifically, the crystal dimensions were lower in the central cortex than in the endosteal and periosteal regions. Mineral crystal orientation followed the cortical circumference in the periosteal and endosteal regions, but was less well-oriented in the central regions. Central cortex is formed rapidly during development through endochondral ossification. Since rats possess no osteonal remodeling, this bone remains (until old age). Significant linear correlations were observed between the dimensional and organizational parameters, e.g., between crystal length and degree of orientation (R(2)=0.83, p<0.001). Application of SAXS/WAXS provides valuable information on bone nanostructure and its constituents, effects of diseases and, prospectively, mechanical competence.
Topics: Animals; Bone Density; Female; Femur; Rats, Sprague-Dawley; Scattering, Small Angle; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction
PubMed: 27417019
DOI: 10.1016/j.jsb.2016.07.005 -
Nanoscale Advances Aug 2021Hierarchical biological materials, such as osteons and plant cell walls, are complex structures that are difficult to mimic. Here, we combine liquid crystal systems and...
Hierarchical biological materials, such as osteons and plant cell walls, are complex structures that are difficult to mimic. Here, we combine liquid crystal systems and polymerization techniques within confined systems to develop complex structures. A single-domain concentric chiral nematic polymeric fiber was obtained by confining cellulose nanocrystals (CNCs) and hydroxyethyl acrylate inside a capillary tube followed by UV-initiated polymerization. The concentric chiral nematic structure continues uniformly throughout the length of the fiber. The pitch of the chiral nematic structure could be controlled by changing the CNC concentration. We tracked the formation of the concentric structure over time and under different conditions with variation of the tube orientation, CNC concentration, CNC type, and capillary tube size. We show that the inner radius of the capillary tube is important and a single-domain structure was only obtained inside small-diameter tubes. At low CNC concentration, the concentric chiral nematic structure did not completely cover the cross-section of the fiber. The highly ordered structure was studied using imaging techniques and X-ray diffraction, and the mechanical properties and structure of the chiral nematic fiber were compared to a pseudo-nematic fiber. CNC polymeric fibers could become a platform for many applications from photonics to complex hierarchical materials.
PubMed: 36132352
DOI: 10.1039/d1na00425e -
Indian Journal of Orthopaedics 2019There has been a lot of research done on Ilizarov's limb lengthening; however, very few publications focus on the quantitative assessment of the distractional bone...
BACKGROUND
There has been a lot of research done on Ilizarov's limb lengthening; however, very few publications focus on the quantitative assessment of the distractional bone regeneration in tibial and femur lengthening. Data regarding quality of the bone after lengthening are needed to consider the time of frame removal and develop a rehabilitation program.
MATERIALS AND METHODS
Computed tomography (CT) assessment of a parent bone was performed on 136 patients with limb length discrepancy and bone deformity of various etiologies before and after lengthening. Transosseous osteosynthesis technique with the Ilizarov's external fixation was used for limb lengthening and deformity correction in all the cases. A 64-slice scanner was used for CT assessments. Specific Roentgen-negative units of the Ilizarov apparatus and techniques for interpreting CT findings were employed for artifact-free densitometric assessment.
RESULTS
Cortical density of the femur and tibia in patients with limb length discrepancy and bone deformity of various etiologies was shown to have differences as compared to the contralateral limb. The lengthening process was accompanied by decreased cortical density of the segment being lengthened, and the decrease in the density was greater in the areas adjacent to the distractional bone regeneration. The cortical structure underwent characteristic changes. Osteonal density of the cortical bone was higher in the norm and at long term followup as compared to the density of external and internal plates.
CONCLUSION
Cortical bone of the femur and tibia in patients with limb length discrepancy and bone deformity of various etiologies showed various preoperative local densities of external, internal, and osteon layers. The cortical bone demonstrated heterogenic structures with resorption areas of various magnitude and density, with minimal values at the boundary with regenerate bone during distraction and fixation with frame on and at short-term followup. Complete organotypical restructuring of the bone was shown to occur at a 1-to-3-year followup depending on the etiology of the disease and amount of lengthening performed.
PubMed: 31303674
DOI: 10.4103/ortho.IJOrtho_443_18