Bone Tissue Types Research Articles

CHANGES IN THE OPTICAL DENSITY OF BONE TISSUE IN DENTAL IMPLANT PLACEMENT

Introduction. The success of dental implant placement depends primarily on the initial stability of the implant and the bone density, which allows achieving the necessary osseointegration for effective treatment. Optimal stability of dental implants depends on the quality and quantity of bone tissue, therefore bone density plays a key role in determining the prognosis of dental implantation, since the survival of implants is strongly correlated with the amount of bone tissue, and bone density is a crucial parameter for assessing the amount of bone tissue. Therefore, lower levels of cancellous bone density and less bone tissue are more likely to lead to dental implant loss. This study aims to evaluate the effectiveness of using a soft tissue cuff reinforced with bone grafting material (BGM) by the follow-up changes in the optical density of bone tissue on the implant side after one-stage dental implant placement. Materials and methods. At the start of the study, two patient groups were formed: the main group, comprising 25 individuals who received BGM (bone grafting material), and the control group, consisting of 26 individuals who did not receive BGM. Optical bone density was assessed prior to implantation, at 3 months, and one year post-implantation using cone beam computed tomography, evaluated according to the C. E. Misch and L. T. Kircos classification. The obtained results were processed using the “Statistica 13” software (Copyright 1984–2018 TIBCO Software Inc. All rights reserved. License No. JPZ8041382130ARCN10-J). Results. The optical density of bone tissue in the area of one-stage dental implantation significantly decreased from the central teeth to the posterior region. In both groups before implantation, it was significantly highest relative to all teeth in the area of central incisors, and significantly lowest relative to almost all teeth in the area of the second premolar and first molar. In the main group had been used, the optical density of bone tissue in the area of one-stage dental implantation in the upper jaw was significantly higher than in the lower jaw. In the control group had been used, no significant difference between the indicators of optical density of bone tissue depending on the jaw was found. In the main group in dental implantation provided a significant increase in the optical density of bone tissue in 3 months by 118.7 HU, and in a year by 175.6 HU; a significant increase in the optical density of bone tissue in a year in the LI area by 233 HU, 2PM area by 503.2 HU and 1M area by 244 HU (in the control group, a significant increase in the optical density of bone tissue was not achieved both in 3 months and a year after implantation) a year after implantation. There was a significant increase in the percentage of D1 and D2 bone types (42.9 % and 45.7 %, respectively), which is significantly higher than D3 type (11.4 %; χ2 = 10.08; p < 0.002 and χ2 = 8.74; p < 0.004, respectively), which indicated successful osseointegration of implants into bone tissue. Conclusions. Adequate optical bone density and the formation of D1/D2 bone tissue types, achieved through the development of a soft tissue cuff reinforced with bone graft material, contribute to improving the efficiency of dental implantation.

The osteohistology of Orthosuchus stormbergi using synchrotron radiation microcomputed tomography.

Orthosuchus stormbergi was a small-bodied crocodyliform, representative of a diverse assemblage of Early Jurassic, early branching crocodylomorph taxa from the upper Elliot Formation of South Africa. The life history of these early branching taxa remains poorly understood, with only sparse investigations into their osteohistology, yet species like Orthosuchus have potential to inform about the macroevolution of growth strategies on the stem leading to crown crocodilians. In order to elucidate the growth patterns of Orthosuchus, we used propagation phase contrast X-ray synchrotron micro-computed tomography to virtually image the osteohistology of the postcrania of two specimens, including multiple elements from the type (SAM-PK-K409), and the femur of a referred specimen (BP/1/4242). In total, we scanned nine mid-diaphyseal sections of the humerus, radius, ulna, radiale, femur, tibia, fibula, and a rib. We then compared our results to osteohistological sections of crocodylomorph taxa from the published literature. Our results show that the most predominant bone tissue type in Orthosuchus is lamellar, with a few patches of woven and parallel-fibred bone. The type specimen contains four to five lines of arrested growth and the hindlimb elements present outer circumferential lamellae, whereas the referred specimen contains six to seven. Both specimens grew at similar rates, reaching adult skeletal body size at year four or five. The sectioned bones, most notably the radius and ulna, are comparatively thick walled and compact. Our virtual osteohistological sections are one of the first for an early branching crocodyliform, and the broad sample of skeletal elements makes Orthosuchus a key anchor point for understanding the plesiomorphic life history traits of the clade.

Combining Multiple Spectroscopic Techniques to Reveal the Effects of Staphylococcus aureus Infection on Human Bone Tissues.

Osteomyelitis (OM) and periprosthetic joint infections (PJIs) are major public health concerns in Western countries due to increased life expectancy. Infections usually occur due to bacterial spread through fractures, implants, or blood-borne transmission. The pathogens trigger an inflammatory response that hinders bone tissue regeneration. Treatment requires surgical intervention, which involves the precise removal of infected tissue, wound cleansing, and local and systemic antibiotic administration. Staphylococcus aureus (SA) is one of the most common pathogens causing infection-induced OM and PJIs. It forms antimicrobial-resistant biofilms and is frequently found in healthcare settings. In this proof-of-concept, we present an approach based on multiple spectroscopic techniques aimed at investigating the effects of SA infection on bone tissue, as well as identifying specific markers useful to detect early bacterial colonization on the tissue surface. A cross-section of a human femoral diaphysis, with negative-culture results, was divided into three parts, and the cortical and trabecular regions were separated from each other. Two portions of each bone tissue type were infected with SA for one and seven days, respectively. Multiple techniques were used to investigate the impact of the infection on bone tissue, Brillouin-Raman microspectroscopy and attenuated total reflection Fourier transform infrared spectroscopy were employed to assess and develop a new noninvasive diagnostic method to detect SA by targeting the bone of the host. The results indicate that exposure to SA infection significantly alters the bone structure, especially in the case of the trabecular type, even after just one day. Moreover, Raman spectral markers of the tissue damage were identified, indicating that this technique can detect the effect of the pathogens' presence in bone biopsies and pave the way for potential application during surgery, due to its nondestructive and contactless nature.

Determinants of bone mineral density in various regions of the skeleton among smokers and non-smokers: the role of physical activity.

The adult human skeleton is composed of cortical and cancellous bone. The proportions of these two types of bone tissue differ in various parts of the skeleton. The aim of this cross-sectional study was to quantify the determinants of bone mineral density (BMD) and bone mineral content in various regions of interest (ROIs) in smokers and never-smokers. In this study, 4,332 bone scans of three regions of interest (ROIs) were analyzed: the forearm (distal and proximal), femur, and lumbar spine. Body composition and bone parameters were measured using dual-energy X-ray absorptiometry. Smoking was measured using the Global Adult Tobacco Survey questionnaire. Body mass index (BMI) was calculated, and physical activity (PA) was characterized by the metabolic equivalent of task (MET). Among women, the interaction between PA (positive β coefficient) and smoking (negative β coefficient) was a significant predictor of BMD in the distal and proximal forearm (adj. R2 = 0.40 and R2 = 0.58; p < 0.001). The interaction of three variables-age, smoking (negative β), and MET (positive β)-was significant for total hip BMD (adj. R2 = 0.54; p < 0.001). The interaction between BMI and MET (positive β) and smoking (negative β) was significant for BMD in the lumbar spine (adj. R2 = 0.62; p < 0.001). In men, the interaction between MET (positive β) and smoking (negative β) was significant for BMD in the forearm and lumbar spine (adj. R2 = 0.44, R2 = 0.46, and R2 = 0.49; p < 0.01). Smoking alone was a significant negative predictor of total hip BMD (adj. R2 = 0.34; p < 0.001). Among both women and men, never-smokers had significantly better bone parameters than smokers. Smoking was a significant negative predictor for BMD in the various ROIs in both women and men. Physical activity was a significant positive predictor of BMD, with a strong association with bone parameters.

Tailoring the properties of composite scaffolds with a 3D-Printed lattice core and a bioactive hydrogel shell for tissue engineering

The optimal performance of scaffolds for tissue engineering relies on a proper combination of their constituent biomaterials and on the design of their structure. In this work, composite scaffolds with a core-shell architecture are realized by grafting a gelatin-chitosan hydrogel onto a 3D-printed polylactic acid (PLA) core, aiming in particular at bone regeneration. This hydrogel was recently found to sustain osteogenic differentiation of mesenchymal stromal cells, leading to new bone tissue formation. Here, the integration with rigid PLA lattice structures provides improved mechanical support and finer control of strength and stiffness. The core is prepared by fused deposition modeling with the specific aim to study several lattice structures and thereby better tune the scaffold mechanical properties. In fact, the core architecture dictates the scaffold strength and stiffness, which are seen to match those of different types of bone tissue. For all lattice types, the hydrogel is found to penetrate throughout the entire core and to present highly interconnected pores for cell colonization. By varying the void volume fraction in the core it is possible to significantly change the bioactive shell content, as well as the mechanical properties, over a wide range of values. Looking for design guidelines, relationships between stiffness/strength and density are here outlined for scaffolds featuring different lattice parameters. Moreover, by acting on the core strut arrangement, scaffolds are reinforced along specific directions, as evaluated under compressive and bending loading conditions.

Novel Technology Allowing Cone Beam Computed Tomography in 6 Seconds: A Patient Study of Comparative Image Quality

PurposeThe goal of this study was to evaluate the image quality provided by a novel cone beam CT (CBCT) platform (HyperSightTM, Varian Medical Systems), a platform with enhanced reconstruction algorithms as well as rapid acquisition times. Image quality was compared to both status quo CBCT for image guidance, and to fan beam CT (FBCT) acquired on a CT simulator (CTsim). MethodsIn a clinical study, 30 subjects were recruited for whom either deep inspiration (DIBH) or deep exhalation breath hold (DEBH) was used during imaging and radiation treatment of tumors involving liver, lung, breast, abdomen, chest wall and pancreatic sites. All subjects were imaged during breath hold with CBCT on a standard image guidance platform (TrueBeam® 2.7, Varian Medical Systems) and FBCT CT (CTsim, GE Optima). HyperSight imaging with both breath hold (HSBH) and free breathing (HSFB) was performed in a single session. The four image sets thus acquired were registered and compared using metrics quantifying artifact index (AI), image non-uniformity, contrast, contrast-to-noise ratio (CNR), and difference of HU from CTsim. ResultsHSBH provided less severe artifacts compared to both HSFB and TrueBeam. The severity of artifacts in HSBH images was similar to that in CTsim images, with statistically similar AI values. CTsim provided the best image uniformity, however HSBH provided improved uniformity compared to both HSFB and TrueBeam. CTsim demonstrated elevated contrast compared to HyperSight imaging, but both HSBH and HSFB imaging showed superior CNR characteristics compared to TrueBeam. The median HU difference of HSBH from CTsim was within 1 HU for muscle/fat tissue, 12 HU for bone and 14 HU for lung. ConclusionThe HyperSight system provides six-second CBCT acquisition with image artifacts that are significantly reduced compared to TrueBeam and comparable to those in CTsim FBCT imaging. HyperSight breath hold imaging was of higher quality compared to free breathing imaging on the same system. The median HU value in HyperSight breath hold imaging is within 15 HU of that in CT simulation imaging for muscle, fat, bone and lung tissue types, indicating the utility of image data for direct dose calculation in adaptive workflows.

Evaluating methods for determining mercury concentrations in ancient marine fish and mammal bones as an approach to assessing millennial-scale fluctuations in marine ecosystems

Millennial-scale datasets of heavy metals in biota are difficult to obtain but are important for determining patterns and underlying drivers of toxicant concentrations. This is particularly important to better discriminate contemporary natural and anthropogenic sources. Globally mercury is a contaminant of concern. Post-industrial increases in mercury in arctic biota have been documented and monitoring of Steller sea lions (Eumetopias jubatus) in the Aleutian Islands, Alaska, has revealed a high proportion of pups with fur mercury concentrations above thresholds of concern in some regions. As bone is a tissue that is well preserved in archeological middens, it may prove useful for developing long-term mercury data sets under appropriate conditions. The goal of this study was to evaluate methodologies for measuring mercury concentration in Steller sea lion bone using a direct mercury analyzer, considering sample preparation methods and variability among bone tissue types (e.g., compact versus spongy bone). Finally, we directly compare sensitivity and precision of two different direct mercury analyzer models. Based on the methods presented here, direct mercury analysis using the Nippon MA-3000 can quantify small (ppb) quantities of Hg accurately and precisely in 20 to 60mg of bone with minimal specimen processing. The described method is efficient, relatively inexpensive, and requires minimal bone, conserving rare and valuable specimens. Hydrogen peroxide cleaning and collagen extraction were not required, and may be detrimental for optimal Hg quantification in bone. Further, while homogenization of distinct compact and spongy bone did not impact concentration determination, variance of technical replicates was lower improving quantitation precision. Most importantly, significant differences between compact and spongy bone exist within some individual specimen; however, the difference is not consistent and may indicate differential Hg exposure windows influenced by turnover rate of bone types. We conclude bone provides a natural archive for mercury ecosystem dynamics over millennial time scales in regions where appropriate samples are available. Compact bone has lower and less variable [THg] simplifying analysis and interpretation of data; however, the more dynamic concentrations observed in spongy bone should not be dismissed as invaluable due to their variability in [THg]. Comparisons of [THg] between bone type within individual may provide insight into more acute changes in mercury exposure within an individual’s lifetime.

Paleobiology of Rinconsaurus caudamirus and Muyelensaurus pecheni (Sauropoda, Titanosauria) from the Neuquén Group, Upper Cretaceous of Argentina: inferences from long bone histology

Titanosauria is the most successful and diverse clade of sauropodomorph dinosaurs, with some of the largest and smallest sauropod species known to date. Rinconsaurus caudamirus and Muyelensaurus pecheni were two small-sized titanosaurs recollected from the Neuquén Group (Upper Cretaceous) of Argentina. The bone remains of both specimens include axial and appendicular elements corresponding to several individuals. These taxa have been anatomically and phylogenetically studied, but did not analyzed from paleohistological viewpoint yet. This contribution focuses on the description of the long bone histology of both species including several aspects of its paleobiology. For this, thin transverse sections were made at the diaphysis level and were analyzed under microscope. The histology of M. pecheni and R. caudamirus shows a uniform bone microstructure similar to other titanosaurs, with changes in bone tissue types being mostly related to the different life story. The major difference between the taxa is in the type of bone matrix. Whereas woven fibered bone predominates in the cortex of M. pecheni, R. caudamirus shows parallel-fibered bone. The presence of this last primary tissue is consistent with the reduced size of R. caudamirus. The long bone histology of M. pecheni resembles that of large basal neosauropods. Contrary to the reported for other noesauropods, the data obtained in this study does not reveal a correlation between the ontogenetic stage and the body size in R. caudamirus and M. pecheni. Finally, as was mentioned previously to others titanosaurs, both specimens show a high rate of secondary remodeling.

Effective investigation of murine femoral bone development utilizing correlative light and electron microscopy (CLEM)

BackgroundFor effective investigation of the developing structure and chemistry of bone, comprehensive studies including compositional analysis can be achieved through the gradual observation from the micro- to nanometer scale via correlative light and electron microscopy (CLEM). This technique is particularly useful considering the complex hierarchical arrangement of bioapatite and collagen fibrils which may vary according to specific bone tissue types (i.e., lamellar bone and woven bone) and different growth stages. Scanning electron microscopy (SEM) accompanied with the attachment of the scanning transmission electron microscopy (STEM) detector, referred to as the STEM-in-SEM can be utilized to produce high contrast images from materials composed of light elements, and efficiently allows the selection of suitable accelerating voltage for energy-dispersive spectroscopy (EDS). This study aims to emphasize the efficacy of CLEM techniques through applying STEM-in-SEM and EDS analyses, and its application to comparative murine bone investigation in differing ontogenetic stages.FindingsWe have designed a new grid-holder which can be used for both light and electron microscopy, and we presented an imaging technique for TEM specimens via reflective light microscopy (RLM). For performing CLEM, ultra-thin-sections (UTS) prepared from the femoral bones of 1- to 16-week old of Sprague-Dawley (SD) rats provided light and electron micrographs that can be correlated based on the regions of interest (ROIs). STEM-in-SEM micrographs revealed information not attainable by secondary electron (SE) and back-scattered electron (BSE) micrographs. In addition, for analyzing chemical variation according to growth and development of femoral bones from 1- to 16-week-old rats, comparative chemical analysis was performed through STEM-in-SEM EDS with two reference materials.ConclusionHerein, from femoral bones of SD rats, we have confirmed the rapid chemical and structural variations within the first 8 weeks after birth. STEM-in-SEM micrographs revealed the bone development process of the early stage porous bone matrix subsequently being filled with collagen fibrils and bioapatite. In addition, chemical analysis for carbon and oxygen showed the ratios of inorganic to organic phases according to growth and progress in bone mineralization. As a result, we were able to postulate the growth mechanism of murine femoral bone in the neonatal stages of development. We also anticipate that our CLEM techniques can be further utilized for more thorough investigation of bone structure and chemistry in diverse scales.

A STATISTICAL META-ANALYSIS OF LITHOLOGIC AND OTHER POTENTIAL CONTROLS ON FOSSIL BONE CELLULAR AND SOFT TISSUE PRESERVATION

ABSTRACT Demineralization assays, utilizing weak acids to isolate organics from biomineralized tissues, have recently been applied with increasing frequency to explore soft tissue preservation in fossils, revealing frequent retention of cells and other pliable microstructures in fossil bones. However, factors controlling long-term preservation of such labile structures remain mysterious. To address this, we compiled a database of bone demineralization results from 29 studies, then conducted a statistical meta-analysis of these data to evaluate the importance of specimen age, taxonomy, entombing lithology, and bone tissue type on microstructure recovery. Our database encompasses results from 137 bones from 44 formations spanning the Permian to the Holocene. Osteocytes, blood vessels, and fibrous/proteinaceous matrix each exhibit bimodal recovery patterns in which most fossil bones either yield many or none of these microstructures. Though their relative abundances in any given fossil bone are extremely variable, statistically significant Fisher's Exact tests found that if a bone yields one of these types of microstructures in abundance then the others are usually also abundant. None of the variables examined significantly influence osteocyte recovery, but Kruskal-Wallis and subsequent pairwise Mann-Whitney tests revealed that bones collected from unconsolidated sediments, of Paleocene age, and/or deriving from birds, amphibians, marine reptiles, or crocodylians often yield few or no vessels and fibrous matrix. Although these findings hint at possible controls on cellular and soft tissue preservation in fossil bones, they should be viewed cautiously as they are demonstrably biased by uneven sampling. For example, many of the apparent trends are substantially controlled by overrepresentation of data from nonavian dinosaur specimens from Cretaceous fluvio-lacustrine deposits. Future demineralization assays should therefore focus on non-mammalian specimens from the Cenozoic and Jurassic-and-older nondinosaurian specimens, especially those preserved in less-common depositional environments (e.g., eolian settings).

Optimization of integration of jaw bone tissue by cellular structures made of titanium impregnated with ascorbic acid

The article presents a study on improving the efficiency of osseointegration processes in the plastic of jaw defects by using ascorbic acid in an experiment.&#x0D; Structured implants with cells of 250 microns, obtained by growing on the Realizer SLM 50 installation, were implanted in guinea pigs in the lower jaw area (observation period of 1 month). For this purpose, 2 groups were formed: the main one — 5 animals and the comparison group — 3 animals. Ascorbic acid was a stimulant for the growth of connective and bone tissue. A method of introducing it into the implant cells has been developed. Studies were carried out on Altami MET-5D, a universal metallographic microscope used to work in reflected light at a magnification of 10 times.&#x0D; As a result of the study, the IV degree of fixation prevailed in the main group (33.3±0.2%), the IV degree of fixation was also revealed in the comparison group (25±0.2%). Using an inductor (Vit. C) coarse-fibrous bone tissue was formed in implants with cells measuring 850 microns (term of 1 month), and in the absence of a modulator, connective tissue and cartilaginous tissue, penetrated by a network of small vessels, prevailed at the same time.&#x0D; It is concluded that implants with a face-centered cubic crystal lattice structure have sufficiently high integration properties. At the same time, the use of vitamin C as a stimulant significantly increases the growth and integration of both connective and various types of bone tissue.

Osteohistology and palaeobiology of giraffids from the Mio-Pliocene Langebaanweg (South Africa).

The reconstruction of life history traits, such as growth rate, age at maturity and age at death can be estimated from the histological analysis of long bones. Here, we studied 20 long bones (metapodials, tibia and femora) of Sivatherium hendeyi and Giraffa cf. Giraffa jumae recovered from the Miocene-Pliocene locality of Langebaanweg on the West Coast of South Africa. We analysed the long bone histology and growth marks of juvenile and adult specimens of these taxa. Our results show that bone tissue types and vascular canal orientation varies during ontogeny, as well as between the different skeletal elements, and also across single cross sections of bones. Majority of our specimens appear to be still growing, with only an adult metacarpal of S. hendeyi being skeletally mature as indicated by the presence of an outer circumferential layer. We propose that the growth marks preserved in the cortices of the bones studied are most likely related to multiple catastrophic events as opposed to being annual/seasonal.

Trabecular Bone Constitutes the Internal Cavity of the Bone

Trabecular bone is a type of bone tissue that forms the inner cavity of the bone. It is more porous and lighter than compact bone. Also, long bones contain trabecular bone at their enlarged ends. In addition, trabecular bone is the main component of the ribs, as well as the shoulders and the flat bones of the skull. Most of the short straight bones of the skeleton are also composed of trabecular bones.

An insight into cancer palaeobiology: does the Mesozoic neoplasm support tissue organization field theory of tumorigenesis?

BackgroundNeoplasms are common across the animal kingdom and seem to be a feature plesiomorphic for metazoans, related with an increase in somatic complexity. The fossil record of cancer complements our knowledge of the origin of neoplasms and vulnerability of various vertebrate taxa. Here, we document the first undoubted record of primary malignant bone tumour in a Mesozoic non-amniote. The diagnosed osteosarcoma developed in the vertebral intercentrum of a temnospondyl amphibian, Metoposaurus krasiejowensis from the Krasiejów locality, southern Poland.ResultsA wide array of data collected from gross anatomy, histology, and microstructure of the affected intercentrum reveals the tumour growth dynamics and pathophysiological aspects of the neoplasm formation on the histological level. The pathological process almost exclusively pertains to the periosteal part of the bone composed from a highly vascularised tissue with lamellar matrix. The unorganised arrangement of osteocyte lacunae observed in the tissue is characteristic for bone tissue types connected with static osteogenesis, and not for lamellar bone. The neoplastic bone mimics on the structural level the fast growing fibrolamellar bone, but on the histological level develops through a novel ossification type. The physiological process of bone remodelling inside the endochondral domain continued uninterrupted across the pathology of the periosteal part.ConclusionsBased on the results, we discuss our case study’s consistence with the Tissue Organization Field Theory of tumorigenesis, which locates the causes of neoplastic transformations in disorders of tissue architecture.

Using an Ultrasound Tissue Phantom Model for Hybrid Training of Deep Learning Models for Shrapnel Detection.

Tissue phantoms are important for medical research to reduce the use of animal or human tissue when testing or troubleshooting new devices or technology. Development of machine-learning detection tools that rely on large ultrasound imaging data sets can potentially be streamlined with high quality phantoms that closely mimic important features of biological tissue. Here, we demonstrate how an ultrasound-compliant tissue phantom comprised of multiple layers of gelatin to mimic bone, fat, and muscle tissue types can be used for machine-learning training. This tissue phantom has a heterogeneous composition to introduce tissue level complexity and subject variability in the tissue phantom. Various shrapnel types were inserted into the phantom for ultrasound imaging to supplement swine shrapnel image sets captured for applications such as deep learning algorithms. With a previously developed shrapnel detection algorithm, blind swine test image accuracy reached more than 95% accuracy when training was comprised of 75% tissue phantom images, with the rest being swine images. For comparison, a conventional MobileNetv2 deep learning model was trained with the same training image set and achieved over 90% accuracy in swine predictions. Overall, the tissue phantom demonstrated high performance for developing deep learning models for ultrasound image classification.

The Promotion of Mechanical Properties by Bone Ingrowth in Additive-Manufactured Titanium Scaffolds.

Although the initial mechanical properties of additive-manufactured (AM) metal scaffolds have been thoroughly studied and have become a cornerstone in the design of porous orthopaedic implants, the potential promotion of the mechanical properties of the scaffolds by bone ingrowth has barely been studied. In this study, the promotion of bone ingrowth on the mechanical properties of AM titanium alloy scaffolds was investigated through in vivo experiments and numerical simulation. On one hand, the osseointegration characteristics of scaffolds with architectures of body-centred cubic (BCC) and diamond were compared through animal experiments in which the mechanical properties of both scaffolds were not enhanced by the four-week implantation. On the other hand, the influences of the type and morphology of bone tissue in the BCC scaffolds on its mechanical properties were investigated by the finite element model of osseointegrated scaffolds, which was calibrated by the results of biomechanical testing. Significant promotion of the mechanical properties of AM metal scaffolds was only found when cortical bone filled the pores in the scaffolds. This paper provides a numerical prediction method to investigate the effect of bone ingrowth on the mechanical properties of AM porous implants, which might be valuable for the design of porous implants.

Additively manufactured lattice structures with controlled transverse isotropy for orthopedic porous implants

Additively manufactured lattice structures enable the design of tissue scaffolds with tailored mechanical properties, which can be implemented in porous biomaterials. The adaptation of bone to physiological loads results in anisotropic bone tissue properties which are optimized for site-specific loads; therefore, some bone sites are stiffer and stronger along the principal load direction compared to other orientations. In this work, a semi-analytical model was developed for the design of transversely isotropic lattice structures that can mimic the anisotropy characteristics of different types of bone tissue. Several design possibilities were explored, and a particular unit cell, which was best suited for additive manufacturing was further analyzed. The design of the unit cell was parameterized and in-silico analysis was performed via Finite Element Analysis. The structures were manufactured additively in metal and tested under compressive loads in different orientations. Finite element analysis showed good correlation with the semi-analytical model, especially for elastic constants with low relative densities. The anisotropy measured experimentally showed a variable accuracy, highlighting the deviations from designs to additively manufactured parts. Overall, the proposed model enables to exploit the anisotropy of lattice structures to design lighter scaffolds with higher porosity and increased permeability by aligning the scaffold with the principal direction of the load.

Structural and Metabolic Changes in Bone.

Simple SummaryBone is an extremely metabolically active tissue that is regenerated and repaired over its lifetime by bone remodeling. Most bone diseases are caused by abnormal restructure processes that undermine bone structure and mechanical strength and trigger clinical symptoms, such as pain, deformity, fracture, and abnormalities of calcium and phosphate homoeostasis. The article examines the main aspects of bone development, anatomy, structure, and the mechanisms of cell and molecular regulation of bone remodeling.As an essential component of the skeleton, bone tissue provides solid support for the body and protects vital organs. Bone tissue is a reservoir of calcium, phosphate, and other ions that can be released or stored in a controlled manner to provide constant concentration in body fluids. Normally, bone development or osteogenesis occurs through two ossification processes (intra-articular and intra-chondral), but the first produces woven bone, which is quickly replaced by stronger lamellar bone. Contrary to commonly held misconceptions, bone is a relatively dynamic organ that undergoes significant turnover compared to other organs in the body. Bone metabolism is a dynamic process that involves simultaneous bone formation and resorption, controlled by numerous factors. Bone metabolism comprises the key actions. Skeletal mass, structure, and quality are accrued and maintained throughout life, and the anabolic and catabolic actions are mostly balanced due to the tight regulation of the activity of osteoblasts and osteoclasts. This activity is also provided by circulating hormones and cytokines. Bone tissue remodeling processes are regulated by various biologically active substances secreted by bone tissue cells, namely RANK, RANKL, MMP-1, MMP-9, or type 1 collagen. Bone-derived factors (BDF) influence bone function and metabolism, and pathophysiological conditions lead to bone dysfunction. This work aims to analyze and evaluate the current literature on various local and systemic factors or immune system interactions that can affect bone metabolism and its impairments.

Examination of the Quality of Particulate and Filtered Mandibular Bone Chips for Oral Implants: An In Vitro Study

(1) Background: Autologous bone is supposed to contain vital cells that might improve the osseointegration of dental implants. The aim of this study was to investigate particulate and filtered bone chips collected during oral surgery intervention with respect to their osteogenic potential and the extent of microbial contamination to evaluate its usefulness for jawbone reconstruction prior to implant placement. (2) Methods: Cortical and cortical-cancellous bone chip samples of 84 patients were collected. The stem cell character of outgrowing cells was characterized by expression of CD73, CD90 and CD105, followed by osteogenic differentiation. The degree of bacterial contamination was determined by Gram staining, catalase and oxidase tests and tests to evaluate the genera of the found bacteria (3) Results: Pre-surgical antibiotic treatment of the patients significantly increased viability of the collected bone chip cells. No significant difference in plasticity was observed between cells isolated from the cortical and cortical-cancellous bone chip samples. Thus, both types of bone tissue can be used for jawbone reconstruction. The osteogenic differentiation was independent of the quantity and quality of the detected microorganisms, which comprise the most common bacteria in the oral cavity. (4) Discussion: This study shows that the quality of bone chip-derived stem cells is independent of the donor site and the extent of present common microorganisms, highlighting autologous bone tissue, assessable without additional surgical intervention for the patient, as a useful material for dental implantology.

Wing and leg bone microstructure reflects migratory demands in resident and migrant populations of the Dark‐eyed Junco (Junco hyemalis)

Migration is the primary strategy that temperate birds use to avoid overwintering under harsh conditions. As a consequence, migratory birds have evolved specific morphological features in their wings and skeleton. However, in addition to varying in overall shape and size, bone can also change at the microstructural level by, for example, increasing its thickness. Such changes are critical to preventing fracture and damage under repeated loading (fatigue), yet it is not known whether migratory behaviour influences bone microstructure. To address this gap in the literature, we performed micro‐computed tomography on skeletons of resident and migrant subspecies of the Dark‐eyed JuncoJunco hyemalis. We investigated the differences in the major wing bone, the humerus, and the major leg bone, the femur. In each bone, we studied the microarchitecture of the two types of bone tissue: cortical bone, the thick outer layer of bone; and trabecular bone, which is the porous network of bone tissue at the ends of long bones. We used linear models to quantify morphological features with respect to body mass and migratory behaviour. Humeri from migratory birds were thinner, wider and had higher overall geometric stiffness, i.e. a higher polar moment of inertia, relative to humeri from resident birds. These features may help keep their bones stiff to maintain their increased body mass during migration. In contrast, migrant femora were shorter, thinner and had lower geometric stiffness than femora of residents, potentially to reduce total body mass. Tissue mineral density was lower in both the humerus and the femur of migratory birds. In addition, migratory subspecies had less trabecular bone (lower bone volume fraction) due primarily to a loss of trabecular thickness. Migratory behaviour may thus select for improved stiffness and fatigue resistance in the wing bones and reduced mass of leg bones. Our work demonstrates how important insights into morphological adaptation can be obtained by investigating bone microstructure.