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Journal of Morphology Feb 2022The teeth of actinopterygian fish, like those of mammals, consist of a thin outer hyper-mineralized layer (enamel or enameloid) that surrounds a core of dentin. While...
The teeth of actinopterygian fish, like those of mammals, consist of a thin outer hyper-mineralized layer (enamel or enameloid) that surrounds a core of dentin. While all mammalian species have a single type of dentin (called orthodentin), various dentin types have been reported in the teeth of actinopterygian fish. The most common type of actinopterygian fish dentin is orthodentin. However, the second most common type of actinopterygian fish dentin, called osteodentin, found in several teleost species and in many Selachians, is structurally radically different from orthodentin. Osteodentin, comprising denteons and inter-denteonal matrix, is characterized by an appearance that is similar to mammalian osteonal bone, however, it lacks cells and a lacuno-canalicular system. The current consensus is that although osteodentin is morphologically different from orthodentin, it is a true dentinal material, the product of odontoblast cells. We present the results of a study of osteodentin found in the teeth of the Atlantic wolffish, Anarhichas lupus. Using a variety of microscopy techniques, high-resolution microCT scans, and micro-indentation we describe the three-dimensional structure of both its components (denteons and inter-denteonal matrix), as well as their mineral density distribution and mechanical properties, at several length-scales. We show that wolffish osteodentin is remarkably similar to the anosteocytic bone of the swords of several swordfish species. We also describe the three-dimensional network of canals found in mature osteodentin. The high density of these canals in a metabolically inactive, acellular tissue casts doubt upon the accepted paradigm, that the canals house a vascular network.
Topics: Animals; Dentin; Fishes; Odontoblasts; Perciformes
PubMed: 34910318
DOI: 10.1002/jmor.21438 -
Bone May 2020The needs of everyday life, such as counting and measuring, are roots of theoretical mathematics. I believe these roots are why mathematical ideas ground research so... (Review)
Review
The needs of everyday life, such as counting and measuring, are roots of theoretical mathematics. I believe these roots are why mathematical ideas ground research so amazingly well within many scientific fields. Initially trained as a theoretical mathematician and having collaborated with non-mathematicians in the field of bone research, I address the advantages and challenges of collaborations across fields of research among investigators trained in different disciplines. I report on the mathematical ideas that have guided my research on the mechanics of bone tissue. I explain how the mathematical ideas of local vs. global properties influence my research. Polarized light microscopy (PLM) is a tool that I use consistently, in association with other microscopy techniques, to investigate bone in its healthy state and in the presence of bone disease, in humans and in animal models. I review the results that I and investigators around the world have obtained with PLM. Applied to thin bone sections, PLM yields extinct (black) and bright (white) signals that are interpreted in terms of the orientation of collagen type I, by means of other microscopy techniques. Collagen type I is an elementary component of bone tissue. Its orientation is important for the mechanical function of bone. Images obtained by PLM at a specific bone site yield big data sets regarding collagen orientation. Multiple data sets in respect of multiple sites are often needed for research because the bone tissue differs by location in response to the distinct forces acting on it. Mathematics, defined by philosophers as the theory of patterns, offers the backdrop for pattern identification in the big data sets regarding collagen orientation. I also discuss the computational aspect of the research, pursuant to which the patterns identified are incorporated in simulations of mechanical behaviors of bone. These mathematical ideas serve to understand the role of collagen orientation in bone fracture risk.
Topics: Animals; Bone Diseases; Bone and Bones; Collagen; Computer Simulation; Humans; Mathematics; Microscopy, Polarization
PubMed: 32088399
DOI: 10.1016/j.bone.2020.115295 -
Clinical Biomechanics (Bristol, Avon) Aug 2023The morphology of osteocyte lacunae varies in bones of different ages and bone pathologies. Osteocyte lacunae can cause stress concentration and initiate microcracks....
BACKGROUND
The morphology of osteocyte lacunae varies in bones of different ages and bone pathologies. Osteocyte lacunae can cause stress concentration and initiate microcracks. However, the influence of changes in osteocyte lacunar shape on microcrack is unknown. Therefore, the aim of this study was to determine the effects of osteocyte lacunae with different shapes on microcrack initiation and propagation.
METHODS
Osteon models containing osteocyte lacunae with different shapes were established. The progressive damage analysis method, based on computer simulations, was used to study the evolution of microdamage within the osteon, including the processes of intralaminar and interlaminar microdamage.
FINDINGS
Models with larger DoE values can effectively delay or prevent the formation of linear microcracks, which ensures high fracture toughness of cortical bone. It is subjected to stronger mechanical stimulation, making it more sensitive to loads. Models with smaller DoE values increase the load threshold for microdamage generation and reduces its impact on bone mechanical performance, making it less susceptible to microdamage than models with larger DoE values.
INTERPRETATION
These findings enhance the limited knowledge of the influence of the lacunar shape on microdamage and contribute to a better understanding of bone biomechanics.
Topics: Humans; Osteocytes; Cortical Bone; Biomechanical Phenomena; Cognition; Computer Simulation
PubMed: 37611387
DOI: 10.1016/j.clinbiomech.2023.106072 -
Journal of the Mechanical Behavior of... Jul 2022Ostriches are the fastest bipeds in the world, but their tibias are very thin. How the thin tibia can withstand the huge momentum impacts of the heavy body during...
Ostriches are the fastest bipeds in the world, but their tibias are very thin. How the thin tibia can withstand the huge momentum impacts of the heavy body during running? The present work revealed that the combination of hierarchical and gradient design strategies was the main reason for their high strength and fracture toughness. The microstructure of ostrich's tibias compact bone was self-assembled into the 6-level hierarchical structure from the hydroxyapatite (HAP) crystals, collagen fiber (sub-nano), mineralized collagen fiber (nano-), mineralized collagen fiber bundle (sub-micro), lamellae (micro-) and osteon (macro-scales). The most distinctive design in the ostrich compact bone was that the HAP crystals were embedded in collagen fibers as well as wrapped in the outer layer of mineral collagen fibers (MCFs) in the form of HAP nanocrystals, thus achieving a high degree of soft and hard combination from the nanoscale. The bending strength was gradient-structure dependent and up to 787.2 ± 40.5 MPa, 4 times that of a human's compact bone. The fracture toughness (K) is 5.8 ± 0.1 MPa m. Several toughening mechanisms, such as crack deflection/twist, bridging, HAP fibers pulling-out, and fracture of the MCF bundles were found in the compact bone.
Topics: Animals; Collagen; Cortical Bone; Fractures, Bone; Humans; Struthioniformes; Tibia
PubMed: 35561599
DOI: 10.1016/j.jmbbm.2022.105262 -
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 -
PloS One 2024The histological, or microscopic, appearance of bone tissue has long been studied to identify species-specific traits. There are several known histological...
The histological, or microscopic, appearance of bone tissue has long been studied to identify species-specific traits. There are several known histological characteristics to discriminate animal bone from human, but currently no histological characteristic that has been consistently identified in human bone exclusive to other mammals. The drifting osteon is a rare morphotype found in human long bones and observationally is typically absent from common mammalian domesticates. We surveyed previously prepared undecalcified histological sections from 25 species (human n = 221; nonhuman primate n = 24; nonprimate n = 169) to see if 1) drifting osteons were indeed more common in humans and 2) this could be a discriminating factor to identify human bone histologically. We conclude that drifting osteons are indeed more prevalent in human and nonhuman primate bone relative to nonprimate mammalian bone. Two criteria identify a rib or long bone fragment as human, assuming the fragment is unlikely to be from a nonhuman primate given the archaeological context: 1) at least two drifting osteons are present in the cross-section and 2) a drifting osteon prevalence (or as a percentage of total secondary osteons) of ≥ 1%. We present a quantitative histological method that can positively discriminate human bone from nonprimate mammalian bone in archaeological contexts.
Topics: Animals; Humans; Haversian System; Prevalence; Mammals; Histological Techniques; Primates
PubMed: 38394068
DOI: 10.1371/journal.pone.0298029 -
Journal of Biomechanics Feb 2020This work investigates how changes in cortical bone microstructure alter the risk of fragility fractures. The secondary osteons of non-osteoporotic (by DXA) women with...
This work investigates how changes in cortical bone microstructure alter the risk of fragility fractures. The secondary osteons of non-osteoporotic (by DXA) women with fragility fractures have reduced lamellar width and greater areas of birefringent brightness in transverse sections, a pathological condition. We used hierarchical finite element (FE) models of the proximal femur of two women aged 67 and 88 (younger and older) during one-legged stance. At specific locations of the anterior-inferior neck (ROI), we analyzed micro-models containing osteons comprised of alternating birefringent extinct and bright lamellae. The plane of lamellar isotropy (XY) was transverse to the osteon longitudinal axis (Z) which was parallel to the femoral neck axis. To evaluate changes in fracture risk with changes in microstructure, we investigated principal and von Mises stresses, and planar stress measures that accounted for transverse isotropy. For both younger and older femurs, 48% to 100% of stress measures were larger in models with healthy architecture than in models with pathological architecture, while controlling for type of lamella and osteon. These findings suggest that bone adaptation reduces stress at most pathological lamellar sites. However, in the bright lamellae of the younger femur, the pathological tensile, compressive and distortional stresses in the transverse plane and distortional stress in the longitudinal planes were larger than the non-negligible corresponding stresses in 6 of the 28 osteon models with healthy architecture, in 5 of the 7 locations. Therefore, a minority of sites with pathological architecture present greater stress, and therefore, greater fracture risk.
Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Cortical Bone; Female; Femur; Fractures, Bone; Humans; Middle Aged; Stress, Mechanical
PubMed: 31898977
DOI: 10.1016/j.jbiomech.2019.109596 -
Medical Engineering & Physics Jul 2022Bone milling force is a key factor to be controlled during the orthopedic surgery. Cutting force has significant influence on the breaking of the tools or causing bone...
Bone milling force is a key factor to be controlled during the orthopedic surgery. Cutting force has significant influence on the breaking of the tools or causing bone cracks. The cutting force depends on machining parameters, cutting tools and the cortical bone tissue. In this paper, rotational speed, feed rate, cutting depth, tool diameter and the osteon orientation are considered as input parameters. For statistical modeling and experimental study, the response surface method was used. Moreover, using the Sobol statistical sensitivity analysis method the effect of each input parameter on the process force is investigated both qualitatively and quantitatively. Results revealed that bone milling force decreases with increasing rotational speed while it increases with feed rate due to an increase in the thickness of the deformed chip as well as an escalation of friction. Moreover, increasing cutting depth due to increased thickness of the deformed chip, increases friction and thus increases cutting force. Additionally, as the diameter of the blade increases, the cutting force increases. Finally, in the perpendicular direction to the osteon, less force is applied to the bone tissue than that of parallel to osteon. Based on Sobol sensitivity analysis, cutting depth (51.4%), feed rate (21.9%), tool rotational speed (19%), milling direction (4.8%) and tool diameter (1.9%) are the most effective respectively. Response optimization was also presented using Derringer algorithm, which provided a minimum cutting force of 3.76 N, when tool diameter of 4 mm, rotational speed of 3000 rpm and feed rate of 100 mm/min and cutting depth of 1 mm were selected in milling perpendicular to the osteon orientation. This research can be used to optimize milling parameters in order to assist robotic surgery and orthopedic tool design.
Topics: Bone and Bones; Cortical Bone; Mechanical Phenomena; Orthopedic Equipment; Orthopedics
PubMed: 35781391
DOI: 10.1016/j.medengphy.2022.103821 -
Anatomical Science International Jan 2020The present study concerns the histological examination of the hind limb of a cat (Felis sp.), with an emphasis on Haversian bone. Acknowledging the variety of obstacles...
The present study concerns the histological examination of the hind limb of a cat (Felis sp.), with an emphasis on Haversian bone. Acknowledging the variety of obstacles to be confronted, during histological studies, it was decided the documentation, description, and comparison of the longitudinal distribution of the main microstructural characteristics. To reveal what remains hidden from the sight of knowledge, the novel Geographical Information Systems (GIS) methodology was followed. In means to provide conclusive and credible results, it was analyzed the full spectrum of the resulted cross sections and not just a statistical acceptable number or a specific region of interest. In addition, having used the right femur and tibia from the same animal, species and age discrepancies were eliminated. More thoroughly, osteon and Haversian canal size and circularity were calculated and spatially analyzed. Absolute and relative osteon population densities (OPDs) and tissue-type distributions were also estimated. The use of GIS software constituted the core of the current research, since its application transformed cross sections into informative maps, where inter-skeletal, inter-cortical, and intra-cortical distributional patterns were directly recognized and accordingly correlated to strain and load regimes. As result, it is provided the histomorphological and histomorphometrical profile of the samples, under the prism of the existing biomechanical regime. Finally, having further deployed the potentials of GIS software, it is verified and promoted the feasibility of histological mapping as an indispensable procedure, aligned with the necessities of modern science, regardless of discipline or background.
Topics: Animals; Cats; Geographic Information Systems; Hindlimb; Software
PubMed: 31535279
DOI: 10.1007/s12565-019-00503-4 -
Brazilian Dental Journal 2021Aiming to evaluate cortical bone microarchitecture and osteonal morphology after irradiation, twelve male New Zealand rabbits were used. The animals were divided:...
Aiming to evaluate cortical bone microarchitecture and osteonal morphology after irradiation, twelve male New Zealand rabbits were used. The animals were divided: control group (no radiation-NIr); and 3 irradiated groups, sacrificed after: 7 (Ir7d); 14 (Ir14d) and 21 (Ir21d) days. A single radiation dose of 30 Gy was used. Computed microtomography analyzed the cortical microarchitecture: cortical thickness (CtTh), bone volume (BV), total porosity (Ct.Po), intracortical porosity (CtPo-cl), channel/pore number (Po.N), fractal dimension (FD) and degree of anisotropy (Ct.DA). After scan, osteonal morphology was histologically assessed by means: area and perimeter of the osteons (O.Ar; O.p) and of the Haversian canals (C.Ar; C.p). Microtomographic analysis were performed by ANOVA, followed by Tukey and Dunnet tests. Osteon morphology analyses were performed by Kruskal-Wallis, and test Dunn's. Cortical thickness was significant difference (p<0.010) between the NIr and irradiated groups, with thicker cortex at Ir7d (1.15±0.09). The intracortical porosity revealed significant difference (p<0.001) between irradiated groups and NIr, with lower value for Ir7d (0.29±0.09). Bone volume was lower in Ir14d compared to control. Area and perimeter of the osteons were statistically different (p<0.0001) between NIr and Ir7d. Haversian canals also revealed lower values (p<0.0001) in Ir7d (80.57±9.3; 31.63±6.5) compared to NIr and irradiated groups. Cortical microarchitecture was affected by radiation, and the effects appear to be time-dependent, mostly regarding the osteons morphology at the initial days. Cortex structure in Ir21d revealed similarities to control suggesting that microarchitecture resembles normal condition after a period.
Topics: Animals; Bone and Bones; Cortical Bone; Fractals; Haversian System; Male; Porosity; Rabbits
PubMed: 33914008
DOI: 10.1590/0103-6440202103384