-
International Journal of Implant... Apr 2022Many points concerning the structure of osseointegration and the surrounding jaw bone remain unclear, and its optimal histological form has yet to be identified. The aim...
PURPOSE
Many points concerning the structure of osseointegration and the surrounding jaw bone remain unclear, and its optimal histological form has yet to be identified. The aim of this study was to clarify the structural characteristics of peri-implant jaw bone on the micro- and nano-scales by quantitatively evaluating bone quality.
METHODS
Five samples of human mandibular bone containing dental implants and one dentate sample that had been in place for some years while the donors were still alive were collected. Bulk staining was performed, and 100-μm-thick polished specimens were prepared. The osteon distributions in peri-implant bone and mandibular cortical bone were measured, after which alignment analysis of biological apatite (BAp) crystallites and anisotropy analysis of collagen fiber orientation using second-harmonic generation imaging were carried out.
RESULTS
Osteons in the vicinity of the implant body ran parallel to it. In the cortical bone at the base of the mandible, however, most osteons were oriented mesiodistally. The preferential alignment of BAp crystallites was generally consistent with osteon orientation. The orientation of collagen fibers in peri-implant jaw bone resembled the concentric rings seen in normal cortical bone, but there were also fibers that ran orthogonally across these concentric fibers.
CONCLUSIONS
These results suggest that the mechanical strain imposed by implants causes the growth of cortical bone-like bone in areas that would normally consist of cancellous bone around the implants, and that its structural characteristics are optimized for the load environment of the peri-implant jaw bone.
Topics: Apatites; Cadaver; Collagen; Dental Implants; Humans; Mandible; Osseointegration
PubMed: 35411479
DOI: 10.1186/s40729-022-00417-3 -
Biomechanics and Modeling in... Jun 2022Bone is an extraordinary biological material that continuously adapts its hierarchical microstructure to respond to static and dynamic loads for offering optimal...
Bone is an extraordinary biological material that continuously adapts its hierarchical microstructure to respond to static and dynamic loads for offering optimal mechanical features, in terms of stiffness and toughness, across different scales, from the sub-microscopic constituents within osteons-where the cyclic activity of osteoblasts, osteoclasts, and osteocytes redesigns shape and percentage of mineral crystals and collagen fibers-up to the macroscopic level, with growth and remodeling processes that modify the architecture of both compact and porous bone districts. Despite the intrinsic complexity of the bone mechanobiology, involving coupling phenomena of micro-damage, nutrients supply driven by fluid flowing throughout hierarchical networks, and cells turnover, successful models and numerical algorithms have been presented in the literature to predict, at the macroscale, how bone remodels under mechanical stimuli, a fundamental issue in many medical applications such as optimization of femur prostheses and diagnosis of the risk fracture. Within this framework, one of the most classical strategies employed in the studies is the so-called Stanford's law, which allows uploading the effect of the time-dependent load-induced stress stimulus into a biomechanical model to guess the bone structure evolution. In the present work, we generalize this approach by introducing the bone poroelasticity, thus incorporating in the model the role of the fluid content that, by driving nutrients and contributing to the removal of wastes of bone tissue cells, synergistically interacts with the classical stress fields to change homeostasis states, local saturation conditions, and reorients the bone density rate, in this way affecting growth and remodeling. Through two paradigmatic example applications, i.e. a cylindrical slice with internal prescribed displacements idealizing a tract of femoral diaphysis pushed out by the pressure exerted by a femur prosthesis and a bone element in a form of a bent beam, it is highlighted that the present model is capable to catch more realistically both the transition between spongy and cortical regions and the expected non-symmetrical evolution of bone tissue density in the medium-long term, unpredictable with the standard approach. A real study case of a femur is also considered at the end in order to show the effectiveness of the proposed remodeling algorithm.
Topics: Biomechanical Phenomena; Bone Density; Bone Remodeling; Femur; Models, Biological; Nutrients; Stress, Mechanical
PubMed: 35394267
DOI: 10.1007/s10237-022-01573-6 -
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 -
Journal of Physiology and Pharmacology... Dec 2021This study aimed to evaluate the effects of chicken eggshell powder rich in calcium and the inorganic form of calcium carbonate on osteoporotic bone structure using an...
This study aimed to evaluate the effects of chicken eggshell powder rich in calcium and the inorganic form of calcium carbonate on osteoporotic bone structure using an animal model of ovariectomized rats. Animals were divided into four groups: sham-operated rats (SHAM group); ovariectomized rats untreated (OVX group); OVX rats treated with eggshell powder (Biomin H® OVX + ECa group; total Ca content 1.5%); and OVX rats receiving inorganic calcium carbonate (calcium carbonate precipitated, total Ca content 1.5%; OVX + ICa group) during 8 weeks. Ovariectomy increased total body weight, plasma alkaline phosphatase activity, cortical bone thickness, periosteal bone apposition, and considerably worsened the trabecular bone microarchitecture. Calcium supplementation in both OVX + ECa and OVX + ICa groups elevated blood supply in the cortical bone when compared to OVX rats. Treatment with eggshell powder, unlike the OVX + ICa group, significantly lowered bone resorption, increased plasma calcium level, relative volume of trabecular bone, and secondary osteon population density, which together contributes to the enhanced bone strength. In addition, sizes of Haversian canals and secondary osteons in OVX + ECa group reached the values of SHAM group. Our results suggest that chicken eggshell powder more effectively ameliorates bone loss in ovariectomized rats than precipitated calcium carbonate.
Topics: Animals; Bone Density; Calcium Carbonate; Chickens; Disease Models, Animal; Egg Shell; Female; Powders; Rats
PubMed: 35377339
DOI: 10.26402/jpp.2021.6.05 -
Journal of Anatomy Jun 2022Dicraeosaurid sauropods are iconically characterized by the presence of elongate hemispinous processes in presacral vertebrae. These hemispinous processes can show an...
Osteohistology of the hyperelongate hemispinous processes of Amargasaurus cazaui (Dinosauria: Sauropoda): Implications for soft tissue reconstruction and functional significance.
Dicraeosaurid sauropods are iconically characterized by the presence of elongate hemispinous processes in presacral vertebrae. These hemispinous processes can show an extreme degree of elongation, such as in the Argentinean forms Amargasaurus cazaui, Pilmatueia faundezi and Bajadasaurus pronuspinax. These hyperelongated hemispinous processes have been variably interpreted as a support structure for a padded crest/sail as a display, a bison-like hump or as the internal osseous cores of cervical horns. With the purpose to test these hypotheses, here we analyze, for the first time, the external morphology, internal microanatomy and bone microstructure of the hemispinous processes from the holotype of Amargasaurus, in addition to a second dicraeosaurid indet. (also from the La Amarga Formatin; Lower Cretaceous, Argentina). Transverse thin-sections sampled from the proximal, mid and distal portions of both cervical and dorsal hemispinous processes reveal that the cortical bone is formed by highly vascularized fibrolamellar bone interrupted with cyclical growth marks. Obliquely oriented Sharpey's fibres are mostly located in the medial and lateral portions of the cortex. Secondary remodelling is evidenced by the presence of abundant secondary osteons irregularly distributed within the cortex. Both anatomical and histological evidence does not support the presence of a keratinized sheath (i.e. horn) covering the hyperelongated hemispinous processes of Amargasaurus, and either, using a parsimonious criterium, in other dicraeosaurids with similar vertebral morphology. The spatial distribution and relative orientation of the Sharpey's fibres suggest the presence of an important system of interspinous ligaments that possibly connect successive hemispinous processes in Amargasaurus. These ligaments were distributed along the entirety of the hemispinous processes. The differential distribution of secondary osteons indicates that the cervical hemispinous processes of Amargasaurus were subjected to mechanical forces that generated higher compression strain on the anterior side of the elements. Current data support the hypothesis for the presence of a 'cervical sail' in Amargasaurus and other dicraeosaurids.
Topics: Animals; Bone and Bones; Dinosaurs; Haversian System; Ligaments; Spine
PubMed: 35332552
DOI: 10.1111/joa.13659 -
Current Osteoporosis Reports Apr 2022Osteocytes are the conductors of bone adaptation and remodelling. Buried inside the calcified matrix, they sense mechanical cues and signal osteoclasts in case of low... (Review)
Review
PURPOSE OF REVIEW
Osteocytes are the conductors of bone adaptation and remodelling. Buried inside the calcified matrix, they sense mechanical cues and signal osteoclasts in case of low activity, and osteoblasts when stresses are high. How do osteocytes detect mechanical stress? What physical signal do they perceive? Finite element analysis is a useful tool to address these questions as it allows calculating stresses, strains and fluid flow where they cannot be measured. The purpose of this review is to evaluate the capabilities and challenges of finite element models of bone, in particular the osteocytes and load-induced activation mechanisms.
RECENT FINDINGS
High-resolution imaging and increased computational power allow ever more detailed modelling of osteocytes, either in isolation or embedded within the mineralised matrix. Over the years, homogeneous models of bone and osteocytes got replaced by heterogeneous and microstructural models, including, e.g. the lacuno-canalicular network and the cytoskeleton. The lacuno-canalicular network induces strain amplifications and the osteocyte protrusions seem to be stimulated much more than the cell body, both by strain and fluid flow. More realistic cell geometries, like minute constrictions of the canaliculi, increase this effect. Microstructural osteocyte models describe the transduction of external stimuli to the nucleus. Supracellular multiscale models (e.g. of a tunnelling osteon) allow to study differential loading of osteocytes and to distinguish between strain and fluid flow as the pivotal stimulatory cue. In the future, the finite element models may be enhanced by including chemical transport and intercellular communication between osteocytes, osteoclasts and osteoblasts.
Topics: Bone and Bones; Finite Element Analysis; Humans; Mechanotransduction, Cellular; Osteocytes; Stress, Mechanical
PubMed: 35298773
DOI: 10.1007/s11914-022-00728-9 -
Journal of the Royal Society, Interface Feb 2022Bone has a sophisticated architecture characterized by a hierarchical organization, starting at the sub-micrometre level. Thus, the analysis of the mechanical and...
Bone has a sophisticated architecture characterized by a hierarchical organization, starting at the sub-micrometre level. Thus, the analysis of the mechanical and structural properties of bone at this scale is essential to understand the relationship between its physiology, physical properties and chemical composition. Here, we unveil the potential of Brillouin-Raman microspectroscopy (BRaMS), an emerging correlative optical approach that can simultaneously assess bone mechanics and chemistry with micrometric resolution. Correlative hyperspectral imaging, performed on a human diaphyseal ring, reveals a complex microarchitecture that is reflected in extremely rich and informative spectra. An innovative method for mechanical properties analysis is proposed, mapping the intermixing of soft and hard tissue areas and revealing the coexistence of regions involved in remodelling processes, nutrient transportation and structural support. The mineralized regions appear elastically inhomogeneous, resembling the pattern of the osteons' lamellae, while Raman and energy-dispersive X-ray images through scanning electron microscopy show an overall uniform distribution of the mineral content, suggesting that other structural factors are responsible for lamellar micromechanical heterogeneity. These results, besides giving an important insight into cortical bone tissue properties, highlight the potential of BRaMS to access the origin of anisotropic mechanical properties, which are almost ubiquitous in other biological tissues.
Topics: Anisotropy; Bone and Bones; Cortical Bone; Haversian System; Humans; Microscopy, Electron, Scanning; Spectrum Analysis, Raman
PubMed: 35104431
DOI: 10.1098/rsif.2021.0642 -
Animals : An Open Access Journal From... Oct 2021The paleohistology of dyrosaurids is known from a small sample, despite being common fossils and representing a rare lineage of crocodylomorphs that survived the...
The paleohistology of dyrosaurids is known from a small sample, despite being common fossils and representing a rare lineage of crocodylomorphs that survived the Cretaceous-Paleogene extinction. Their lifestyle has been inferred only from sections of the snout, vertebrae, partial femur, and tibia. To improve this, we conducted a skeletochronological and paleohistological study of midshaft cross-sections of both femora and humeri of a nearly complete skeleton. We found lamellar-zonal bone that underwent remodeling, evidenced by resorption cavities and abundant secondary osteons within the primary periosteal cortex. The osteons, mostly longitudinally oriented and arranged in circular rows, often anastomose radially along a linear path, resembling radial rows. The medullary cavity is completely open, lacking trabeculae: endosteal deposition is limited to thin lamellae surrounding the cavity. Analysis of cyclical growth marks and the presence of an external fundamental system indicate the specimen was a fully mature adult 17-18 years of age. Comparison of the skeleton to others suggests sexual dimorphism and that it was female. The open medullary cavity, and no evidence for pachyosteosclerosis, osteosclerosis, osteoporosis, or pachyostosis indicate was not a deep diver or a fast swimmer in the open ocean but a near-shore marine ambush predator.
PubMed: 34827799
DOI: 10.3390/ani11113067 -
Archives of Craniofacial Surgery Oct 2021Bone grafts can provide an optimal environment for permanent tooth to erupt and enhance the stability of the alveolar maxilla. Although autologous bone is an optimal...
BACKGROUND
Bone grafts can provide an optimal environment for permanent tooth to erupt and enhance the stability of the alveolar maxilla. Although autologous bone is an optimal source for osteogenesis, its inevitable donor site morbidity has led to active research on bone substitutes. This study was designed to evaluate the safety and feasibility of using biphasic calcium phosphate (BCP; Osteon) as a bone substitute in dogs.
METHODS
Bilateral third and fourth premolars of four 15-week-old mongrel dogs were used. All teeth were extracted except the third premolar of the right mandible, which was used as a control. After extraction of the premolars, each dog was administered BCP (Osteon), demineralized bone matrix (DBM; DBX), and no graft in the hollow sockets of the right fourth premolar, left fourth premolar, and left third premolar, respectively. Radiographs were taken at 2-week intervals to check for tooth eruption. After 8 weeks, each dog was sacrificed, and tooth and bone biopsies were performed to check for the presence of tooth and bone substitute particle remnants.
RESULTS
Four weeks after the operation, permanent tooth eruptions had started at all the extraction sites in each dog. Eight weeks after the operation, all teeth had normally erupted, and histological examination revealed BCP particles at the right fourth premolar.
CONCLUSION
In all four dogs, no delay in the eruption of the teeth or shape disfigurement of permanent teeth was observed on gross inspection and radiologic evaluation. On histological examination, most of the BCP and DBM were replaced by new bone. Bone substitutes can be used as graft materials in patients with alveolar clefts.
PubMed: 34732035
DOI: 10.7181/acfs.2021.00325 -
Wiadomosci Lekarskie (Warsaw, Poland :... 2021The aim: To evaluate morphological changes in long tubular bones of mature rats under the influence of experimental hyperglycemia.
OBJECTIVE
The aim: To evaluate morphological changes in long tubular bones of mature rats under the influence of experimental hyperglycemia.
PATIENTS AND METHODS
Materials and methods: The study was conducted on 140 nonlinear white male rats divided into two groups. The experimental group included rats that were introduced into a state of hyperglycemia by a single intraperitoneal injection of an alloxan dihydrate solution at a dose of 150 mg / kg body weight in 0.9% sodium chloride. The control group included rats that were injected with a similar volume of 0.9% sodium chloride one time intraperitoneally. The animals were taken out of the experiment on the 2nd, 30th, 60th, 90th, 120th, 150th and 180th day. Right and left femur and humerus were studied by morphometric and histological methods.
RESULTS
Results: Under conditions of prolonged uncontrolled hyperglycemia in mature rats, there is a slowdown in the growth rate of length and thickness of femur and humerus. This is indicated by a significant decrease in the length of bone and its diaphyses, as well as by a decrease in the cross-sectional area of the diaphysis, the width of the proximal and distal epiphyses, starting from 120 and 90 days of the experiment, respectively. The relative area of trabecular tissue, thickness of trabeculae and epiphyseal cartilage decreases in comparison with animals of the control group. The diameter of osteons and their channels increases in cortical tissue. Changes in the microarchitecture of the trabecular and cortical compartments of femur and humerus under conditions of hyperglycemia are similar and are characterized by a reduced bone mass, bone disorder progression and remodeling disorders.
CONCLUSION
Conclusions: Prolonged uncontrolled experimental hyperglycemia leads to slow growth of femur and humerus in mature rats, which is accompanied by an increase in microarchitecture disorder of the trabecular and cortical compartments, causing miniaturization of bones and, consequently, violation of their biomechanical properties and increased risk of fractures.
Topics: Animals; Bone Density; Bone and Bones; Femur; Fractures, Bone; Hyperglycemia; Male
PubMed: 34725275
DOI: No ID Found