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Journal of the Mechanical Behavior of... Aug 2023The research focuses on the evaluation of the mechanical properties of osteonal cortical bone at the lamellar level. Elastic properties of the mid-diaphysis region of...
The research focuses on the evaluation of the mechanical properties of osteonal cortical bone at the lamellar level. Elastic properties of the mid-diaphysis region of the bovine tibia are investigated via cantilever-based nanoindentation at the submicron length scale utilizing Atomic Force Microscopy, where the force-displacement curves are used for the elastic assessment using the Derjaguin-Muller-Toropov model to calculate indentation modulus. Variations of the modulus and the directional mechanical response of the osteonal bone at different distances from the Haversian canal are investigated. Additionally, the effects of demineralization on the indentation modulus are discussed. It was found that in the axial direction, the first and last untreated thick lamella layers show a significant indentation modulus difference compared to all other layers (4.26 ± 0.4 and 4.6 ± 0.3 GPa vs ∼3.5 GPa). On the other hand, the indentation modulus of transverse thick lamella layers shows a periodic variation between ∼3 ± 0.7 GPa and ∼4 ± 0.3 GPa from near the Haversian canal to near the interstitial bone. A periodic variation in the anisotropy ratio was found. Mineral content was quantified via energy-dispersive X-ray microanalysis at different levels of mineralization and shows a positive correlation with the indentation modulus.
Topics: Animals; Cattle; Tibia; Anisotropy; Bone and Bones; Cortical Bone; Elasticity
PubMed: 37393887
DOI: 10.1016/j.jmbbm.2023.105992 -
Materials (Basel, Switzerland) Jun 2023Mechanical processing of cortical bone tissue is one of the most common surgical procedures. A critical issue accompanying this processing is the condition of the...
Mechanical processing of cortical bone tissue is one of the most common surgical procedures. A critical issue accompanying this processing is the condition of the surface layer, which can stimulate tissue growth and serve as a drug carrier. A comparison of the surface condition before and after orthogonal and abrasive processing was conducted to validate the influence of bone tissue's processing mechanism and orthotropic properties on the surface topography. A cutting tool with a defined geometry and a custom-made abrasive tool was used. The bone samples were cut in three directions, depending on the orientation of the osteons. The cutting forces, acoustic emission, and surface topography were measured. The level of isotropy and the topography of the grooves showed statistical differences relative to the anisotropy directions. After orthogonal processing, the surface topography parameter Ra was determined from 1.38 ± 0.17 μm to 2.82 ± 0.32. In the case of abrasive processing, no correlation was found between the orientation of osteons and topographical properties. The average groove density for abrasive machining was below 1004 ± 0.7, and for orthogonal, it was above 1156 ± 58. Due to the positive properties of the developed bone surface, it is advisable to cut in the transverse direction and parallel to the axis of the osteons.
PubMed: 37374480
DOI: 10.3390/ma16124293 -
Journal of Morphology Jul 2023Bone is a dynamic tissue capable of adapting to its loading environment, allowing the skeleton to remain structurally sound throughout life. One way adaptation occurs in...
Bone is a dynamic tissue capable of adapting to its loading environment, allowing the skeleton to remain structurally sound throughout life. One way adaptation occurs in mammals is via Haversian remodeling: the site-specific, coupled resorption and formation of cortical bone that results in secondary osteons. Remodeling occurs at a baseline rate in most mammals, but it also occurs in relation to strain by repairing deleterious microdamage. Yet, not all animals with bony skeletons remodel. Among mammals, there is inconsistent or absent evidence for Haversian remodeling among monotremes, insectivores, chiropterans, cingulates, and rodents. Three possible explanations for this disparity are discussed: the capacity for Haversian remodeling, body size as a constraint, and age and lifespan as constraints. It is generally accepted, although not thoroughly documented, that rats (a common model used in bone research) do not typically exhibit Haversian remodeling. The present aim is to more specifically test the hypothesis that rats of advanced age do remodel intracortically because of the longer lifespan over which baseline remodeling could occur. Most published histological descriptions of rat bone only include young (3-6 months) rats. Excluding aged rats possibly overlooks a transition from modeling (i.e., bone growth) to Haversian remodeling as the primary mode of bone adaptation. Here, midshaft and distal femora (typical sites for remodeling in other mammals) of 24-month-old rats were examined for presence of secondary osteons. None were found, suggesting that Haversian remodeling does not occur in rats under normal physiological conditions at any age. A likely explanation is that modeling of cortical bone continues throughout most of the short rat lifespan, negating the stimulus for Haversian remodeling. Thorough sampling of key rodent taxa of varying body sizes and lifespans is key to elucidating the reasons why (i.e., body size, age/lifespan, phylogenetic factors) Haversian remodeling might not occur in all mammals.
Topics: Rats; Animals; Longevity; Haversian System; Phylogeny; Mammals; Femur
PubMed: 37313764
DOI: 10.1002/jmor.21600 -
Journal of Anatomy Nov 2023We analyzed pedicle bone from roe bucks that had died around antler casting or shortly before or during the rutting period. Pedicles obtained around antler casting were...
We analyzed pedicle bone from roe bucks that had died around antler casting or shortly before or during the rutting period. Pedicles obtained around antler casting were highly porous and showed signs of intense osteoclastic activity that had caused the formation of an abscission line. Following the detachment of the antler plus a portion of pedicle bone, osteoclastic activity in the pedicles continued for some time, and new bone was deposited onto the separation plane of the pedicle stump, leading to partial pedicle restoration. Pedicles obtained around the rutting period were compact structures. The newly formed, often very large secondary osteons, which had filled the resorption cavities, exhibited a lower mineral density than the persisting older bone. The middle zones of the lamellar infilling frequently showed hypomineralized lamellae and enlarged osteocyte lacunae. This indicates a deficiency in mineral elements during the formation of these zones that occurred along with peak antler mineralization. We suggest that growing antlers and compacting pedicles compete for mineral elements, with the rapidly growing antlers being the more effective sinks. The competition between the two simultaneously mineralizing structures is probably more severe in Capreolus capreolus than in other cervids. This is because roe bucks regrow their antlers during late autumn and winter, a period of limited food and associated mineral supply. The pedicle is a heavily remodeled bone structure with distinct seasonal variation in porosity. Pedicle remodeling differs in several aspects from the normal bone remodeling process in the mammalian skeleton.
Topics: Animals; Antlers; Deer; Bone and Bones; Bone Resorption; Minerals
PubMed: 37278321
DOI: 10.1111/joa.13908 -
Bone Aug 2023Osteopetrosis (OPT) denotes the consequences from failure of osteoclasts to resorb bone and chondroclasts to remove calcified physeal cartilage throughout growth....
Osteopetrosis (OPT) denotes the consequences from failure of osteoclasts to resorb bone and chondroclasts to remove calcified physeal cartilage throughout growth. Resulting impairment of skeletal modeling, remodeling, and growth compromises widening of medullary spaces, formation of the skull, and expansion of cranial foramina. Thus, myelophthisic anemia, raised intracranial pressure, and cranial nerve palsies complicate OPT when severe. Osteopetrotic bones fracture due to misshaping, failure of remodeling to weave the collagenous matrix of cortical osteons and trabeculae, persistence of mineralized growth plate cartilage, "hardening" of hydroxyapatite crystals, and delayed healing of skeletal microcracks. Teeth may fail to erupt. Now it is widely appreciated that OPT is caused by germline loss-of-function mutation(s) usually of genes involved in osteoclast function, but especially rarely of genes necessary for osteoclast formation. Additionally, however, in 2003 we published a case report demonstrating that prolonged excessive dosing during childhood of the antiresorptive aminobisphosphonate pamidronate can sufficiently block osteoclast and chondroclast activity to recapitulate the skeletal features of OPT. Herein, we include further evidence of drug-induced OPT by illustrating osteopetrotic skeletal changes from repeated administration of high doses of the aminobisphosphonate zoledronic acid (zoledronate) given to children with osteogenesis imperfecta.
Topics: Child; Humans; Osteopetrosis; Osteoclasts; Zoledronic Acid; Fractures, Bone; Skull
PubMed: 37172883
DOI: 10.1016/j.bone.2023.116788 -
Acta Biomaterialia Aug 2023Velar bone is the material that fills the horncore of bighorn sheep rams. The architectural dimensions of velar bone are orders of magnitude larger than trabecular bone,...
Velar bone is the material that fills the horncore of bighorn sheep rams. The architectural dimensions of velar bone are orders of magnitude larger than trabecular bone, and velae are more sail-like compared to strut-like trabeculae. Velar bone is important for energy absorption and reduction of brain cavity accelerations during high energy head impacts, but velar bone material properties were previously unknown. It was hypothesized that velar bone tissue would have properties that are beneficial for increased energy absorption at the material level. Solid velar bone beams were tested using dynamic mechanical analysis and three-point bending to quantify mechanical properties. Additionally, the porosity, osteon population density, and mineral content of the solid velar sails were quantified. The velar bone damping factor (∼0.03 - 0.06) and modulus of toughness (3.9 ± 0.4 MJ/m) were lower than other mammalian cortical bone tissues. The solid bony sails have a bending modulus (8.6 ± 0.5 GPa) that lies within the range of bending moduli values previously reported for individual trabecular struts and cortical bone tissue. The solid velar bone sails had porosity (6.7 ± 0.9 %) and bone mineral content (66 ± 1 %) in the range of cortical bone values. Interestingly, velar sails contained osteons, which are rarely found in trabecular struts. The velar bone osteon population density (5.8 ± 0.9 osteons/mm) is in the low end of the range of values reported for cortical bone in other mammals. STATEMENT OF SIGNIFICANCE: Bighorn sheep rams sustain high energy head impacts during intraspecific combat without overt signs of brain injury. Previous studies have shown that the bony horncore plays a critical role in energy absorption and reduction of brain cavity accelerations post impact, which has implications for concussion prevention in humans. However, the material properties of the horncore velar bone were previously unknown. This study quantified the material properties and structure-property relationships of the horncore velar bone at the tissue level. Results from this study will improve our understanding of how bighorn sheep mitigate brain injury during head-to-head impacts and may inspire the design of novel materials for energy absorption applications (i.e., helmets materials that reduce concussion occurrence in humans).
Topics: Humans; Animals; Male; Sheep; Sheep, Bighorn; Skull; Bone Density; Porosity; Brain Injuries
PubMed: 37164299
DOI: 10.1016/j.actbio.2023.05.013 -
IUCrJ May 2023The article by Grünewald et al. [IUCrJ (2023). 10, 189-198] is corrected.
The article by Grünewald et al. [IUCrJ (2023). 10, 189-198] is corrected.
PubMed: 37144818
DOI: 10.1107/S2052252523002695 -
Compendium of Continuing Education in... May 2023This article describes the use of technology capable of converting a failed dentition to a full-arch screw-retained implant-supported provisional restoration in one day...
This article describes the use of technology capable of converting a failed dentition to a full-arch screw-retained implant-supported provisional restoration in one day using a fully digital restorative protocol. With this expedited digital treatment, the transition to a restored dentition is completed without the need for any physical impressions. Predicated on facially driven virtual smile designs, sophisticated engineering designs, complex algorithms, artificial intelligence, and novel laboratory and clinical workflows, the protocol allows for streamlined, same-day digital delivery of an in-house 3D-printed provisional prosthesis after implant placement surgery.
Topics: Dental Implantation, Endosseous; Dental Implants; Artificial Intelligence; Dental Prosthesis, Implant-Supported; Immediate Dental Implant Loading
PubMed: 37134290
DOI: No ID Found -
Romanian Journal of Morphology and... 2023Bone graft materials are more and more frequently used in dentistry for improving the periodontal support and for creating a bone support favorable for the insertion of...
Bone graft materials are more and more frequently used in dentistry for improving the periodontal support and for creating a bone support favorable for the insertion of dental implants. The experimental study carried out on laboratory animals aimed to evaluate the biocompatibility and the manner of integration of an experimental bone augmentation material, based on hydroxyapatite (HAp), reinforced with titanium-based particles by comparison with a commercial synthetic graft material already existing on the profile market, also based on HAp. We noticed a common pattern of evolution, although there were differences related to the speed of new bone tissue formation and implicitly the morphological elements captured at the two moments of time. In the presence of both synthetic materials, ossification also begins from the center of the cavity at distance from the margins of the bone defect, with a common pattern with an appearance with the presence of osteon-like structures. The experimental material generally determined a more intense initial inflammatory reaction, followed by the generation of a repair bone tissue with a denser appearance but with a less uniform structure and a greater number of residual particles.
Topics: Animals; Durapatite; Osseointegration; Titanium; Osteogenesis; Bone and Bones; Dental Implants
PubMed: 37128791
DOI: 10.47162/RJME.64.1.06 -
Acta Biomaterialia Sep 2023The development of treatment strategies for skeletal diseases relies on the understanding of bone mechanical properties in relation to its structure at different length...
The development of treatment strategies for skeletal diseases relies on the understanding of bone mechanical properties in relation to its structure at different length scales. At the microscale, indention techniques can be used to evaluate the elastic, plastic, and fracture behaviour of bone tissue. Here, we combined in situ high-resolution SRµCT indentation testing and digital volume correlation to elucidate the anisotropic crack propagation, deformation, and fracture of ovine cortical bone under Berkovich and spherical tips. Independently of the indenter type we observed significant dependence of the crack development due to the anisotropy ahead of the tip, with lower strains and smaller crack systems developing in samples indented in the transverse material direction, where the fibrillar bone ultrastructure is largely aligned perpendicular to the indentation direction. Such alignment allows to accommodate the strain energy, inhibiting crack propagation. Higher tensile hoop strains generally correlated with regions that display significant cracking radial to the indenter, indicating a predominant Mode I fracture. This was confirmed by the three-dimensional analysis of crack opening displacements and stress intensity factors along the crack front obtained for the first time from full displacement fields in bone tissue. The X-ray beam significantly influenced the relaxation behaviour independent of the tip. Raman analyses did not show significant changes in specimen composition after irradiation compared to non-irradiated tissue, suggesting an embrittlement process that may be linked to damage of the non-fibrillar organic matrix. This study highlights the importance of three-dimensional investigation of bone deformation and fracture behaviour to explore the mechanisms of bone failure in relation to structural changes due to ageing or disease. STATEMENT OF SIGNIFICANCE: Characterising the three-dimensional deformation and fracture behaviour of bone remains essential to decipher the interplay between structure, function, and composition with the aim to improve fracture prevention strategies. The experimental methodology presented here, combining high-resolution imaging, indentation testing and digital volume correlation, allows us to quantify the local deformation, crack propagation, and fracture modes of cortical bone tissue. Our results highlight the anisotropic behaviour of osteonal bone and the complex crack propagation patterns and fracture modes initiating by the intricate stress states beneath the indenter tip. This is of wide interest not only for the understanding of bone fracture but also to understand other architectured (bio)structures providing an effective way to quantify their toughening mechanisms in relation to their main mechanical function.
Topics: Sheep; Animals; Synchrotrons; Anisotropy; Bone and Bones; Cortical Bone; Fractures, Bone; Stress, Mechanical
PubMed: 37127075
DOI: 10.1016/j.actbio.2023.04.038