MicroRNAs are short, single-stranded ribonucleic acids expressed endogenously in the body to regulate gene expression at the post-translational level, with exogenous microRNA offering an attractive approach to therapy. Among the myriad microRNA candidates involved in controlling bone homeostasis and remodeling, microRNA 21 (miR21) is the most abundant. This paper discusses the studies conducted on the role and mechanism of human miR21 (hsa-miR21) in the regulation of bones and the various pathways mediated by miR21, and explores the feasibility of employing exogenous miR21 as a strategy for promoting osteogenesis. From the literature review, it was clear that miR21 plays a dual role in bone metabolism by regulating both bone formation and bone resorption. There is substantial evidence to date from both in vitro and in vivo studies that exogenous miR21 can successfully accelerate new bone synthesis in the context of bone loss due to injury or osteoporosis. This supports the exploration of applications of exogenous miR21 in bone regenerative therapy in the future.
Osteoporosis and osteoarthritis continue to pose significant challenges to the aging population, with limited preventive options and pharmacological treatments often accompanied by side effects. Amidst ongoing efforts to discover new therapeutic agents, tocotrienols (TTs) have emerged as potential candidates. Derived from annatto bean and palm oil, TTs have demonstrated efficacy in improving skeletal and joint health in numerous animal models of bone loss and osteoarthritis. Mechanistic studies suggest that TTs exert their effects through antioxidant, anti-inflammatory, Wnt-suppressive, and mevalonate-modulating mechanisms in bone, as well as through self-repair mechanisms in chondrocytes. However, human clinical trials in this field remain scarce. In conclusion, TTs hold promise as agents for preventing osteoporosis and osteoarthritis, pending further evidence from human clinical trials.
Matched MeSH terms: Bone and Bones/drug effects; Bone and Bones/metabolism
Even though variety of foreign bodies has been reported in a various locations in the craniofacial region, wooden foreign bodies are uncommon. Appropriate management of wooden foreign bodies is considered essential because of their infectious complications and difficulty in radiographic localization. Even though literature is replete with articles on management of foreign bodies in the craniofacial region, specific management of wooden foreign bodies are rarely reported. The purpose of this article is to report two cases of deeply placed wooden foreign body and a protocol for managing them in the maxillofacial region.
Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p
Matched MeSH terms: Bone and Bones/pathology; Bone and Bones/physiopathology*; Bone and Bones/chemistry*
Despite the excellent in vitro and in vivo performance of akermanite ceramic, its poor toughness and strength limit the biomedical application, particularly under load. Herein, the incorporation of strontium enhanced the physicomechanical properties of akermanite and this is ascribed to the decrease in grain size and better sinterability. To investigate the biological performance, the bone-cell interaction with sintered pellets was assessed by in vitro biocompatibility with human fetal osteoblast cell (hFOB). The cell viability using MTT assay revealed that the Ca1.9Sr0.1MgSi2O7 pellets with finer grain size provided better interaction between the cells compared to the unsubstituted counterpart with larger grain size. Our findings highlighted that the synergistic effect of controlled degradation rate and release of Sr2+ into the medium enhanced the in vitro biological properties of akermanite-based materials.
The mechanical properties of tissue scaffolds are essential in providing stability for tissue repair and growth. Thus, the ability of scaffolds to withstand specific loads is crucial for scaffold design. Most research on scaffold pores focuses on grids with pore size and gradient structure, and many research models are based on scaffolding with vertically arranged holes. However, little attention is paid to the influence of the distribution of holes on the mechanical properties of the scaffold. To address this gap, this research investigates the effect of pore distribution on the mechanical properties of tissue scaffolds. The study involves four types of scaffold designs with regular and staggered pore arrangements and porosity ranging from 30% to 80%. Finite element analysis (FEA) was used to compare the mechanical properties of different scaffold designs, with von-Mises stress distribution maps generated for each scaffold. The results show that scaffolds with regular vertical holes exhibit a more uniform stress distribution and better mechanical performance than those with irregular holes. In contrast, the scaffold with a staggered arrangement of holes had a higher probability of stress concentration. The study emphasized the importance of balancing porosity and strength in scaffold design.
Bones are nanocomposites consisting of a collagenous fibre network, embedded with calcium phosphates mainly hydroxyapatite (HA) nanocrystallites. As bones are subjected to continuous loading and unloading process every day, they often tend to become prone to fatigue and breakdown. Therefore, this review addresses the use of nanocomposites particularly polymers reinforced with nanoceramics that can be used as load bearing bone implants. Further, nanocomposite preparation and dispersion modification techniques have been highlighted along with thorough discussion on the influence that various nanofillers have on the physico-mechanical properties of nanocomposites in relation to that of natural bone properties. This review updates the nanocomposites that meet the physico-mechanical properties (strength and elasticity) as well as biocompatibility requirement of a load bearing bone implant and also attempts to highlight the gaps in the reported studies to address the fatigue and creep properties of the nanocomposites.
Osteoradionecrosis is a severe debilitating complication; it may occur from radiotherapy to the bones. It is a dental surgeon's nightmare as it may be long standing and difficult to manage. Osteoradionecrosis is characterised by hypoxia, hypocellularity and hypovascularity of the affected tissue. This paper reviews osteoradionecrosis in relation to dental treatment.
Human bones can be categorised into one of two types--the compact cortical and the porous cancellous. Whilst the cortical is a solid structure macroscopically, the structure of cancellous bone is highly complex with plate-like and strut-like structures of various sizes and shapes depending on the anatomical site. Reconstructing the actual structure of cancellous bone for defect filling is highly unfeasible. However, the complex structure can be simplified into an idealised structure with similar properties. In this study, two idealised architectures were developed based on morphological indices of cancellous bone: the tetrakaidecahedral and the prismatic. The two architectures were further subdivided into two types of microstructure, the first consists of struts only and the second consists of a combination of plates and struts. The microstructures were transformed into finite element models and displacement boundary condition was applied to all four idealised cancellous models with periodic boundary conditions. Eight unit cells extracted from the actual cancellous bone obtained from micro-computed tomography were also analysed with the same boundary conditions. Young's modulus values were calculated and comparison was made between the idealised and real cancellous structures. Results showed that all models with a combination of plates and struts have higher rigidity compared to the one with struts only. Values of Young's modulus from eight unit cells of cancellous bone varied from 42 to 479 MPa with an average of 234 MPa. The prismatic architecture with plates and rods closely resemble the average stiffness of a unit cell of cancellous bone.
Matched MeSH terms: Bone and Bones/anatomy & histology*; Bone and Bones/physiology
There are millions of orthopedic surgeries and dental implantation procedures performed every year globally. Most of them involve machining of bones and cartilage. However, theoretical and analytical study on bone machining is lagging behind its practice and implementation. This study views bone machining as a machining process with bovine bone as the workpiece material. Turning process which makes the basis of the actually used drilling process was experimented. The focus is on evaluating the effects of three machining parameters, that is, cutting speed, feed, and depth of cut, to machining responses, that is, cutting forces and surface roughness resulted by the turning process. Response surface methodology was used to quantify the relation between the machining parameters and the machining responses. The turning process was done at various cutting speeds (29-156 m/min), depths of cut (0.03 -0.37 mm), and feeds (0.023-0.11 mm/rev). Empirical models of the resulted cutting force and surface roughness as the functions of cutting speed, depth of cut, and feed were developed. Observation using the developed empirical models found that within the range of machining parameters evaluated, the most influential machining parameter to the cutting force is depth of cut, followed by feed and cutting speed. The lowest cutting force was obtained at the lowest cutting speed, lowest depth of cut, and highest feed setting. For surface roughness, feed is the most significant machining condition, followed by cutting speed, and with depth of cut showed no effect. The finest surface finish was obtained at the lowest cutting speed and feed setting.
Matched MeSH terms: Bone and Bones/physiology*; Bone and Bones/surgery*
As drilling generates substantial bone thermomechanical damage due to inappropriate cutting tool selection, researchers have proposed various approaches to mitigate this problem. Among these, improving the drill bit design is one of the most feasible and economical solutions. The theory and applications in drill design have been progressing, and research has been published in various fields. However, pieces of information on drill design are dispersed, and no comprehensive review paper focusing on this topic. Systemizing this information is crucial and, therefore, the impetus of this review. Here, we review not only the state-of-the-art in drill bit designs-advances in surgical drill bit design-but also the influences of each drill bit geometries on bone damage. Also, this work provides future directions for this topic and guidelines for designing an improved surgical drill bit. The information in this paper would be useful as a one-stop document for clinicians, engineers, and researchers who require information related to the tool design in bone drilling surgery.
Matched MeSH terms: Bone and Bones/injuries; Bone and Bones/surgery*
Osteoprogenitor cells have been reported to be present in periosteum, cancellous and cortical bone, and bone marrow; but no attempt to identify the best cell source for bone tissue engineering has yet been reported. In this study, we aimed to investigate the growth and differentiation pattern of cells derived from these four sources in terms of cell doubling time and expression of osteoblast-specific markers in both monolayer cells and three-dimensional cell constructs in vitro. In parallel, human plasma derived-fibrin was evaluated for use as biomaterial when forming three-dimensional bone constructs. Our findings showed osteoprogenitor cells derived from periosteum to be most proliferative followed by cortical bone, cancellous bone, and then bone marrow aspirate. Bone-forming activity was observed in constructs formed with cells derived from periosteum, whereas calcium deposition was seen throughout the constructs formed with cells derived from cancellous and cortical bones. Although no mineralization activity was seen in constructs formed with osteoprogenitor cells derived from bone marrow, well-organized lacunae as would appear in the early phase of bone reconstruction were noted. Scanning electron microscopy evaluation showed cell proliferation throughout the fibrin matrix, suggesting the possible application of human fibrin as the bioengineered tissue scaffold at non-load-bearing sites.
A nearly complete human skeleton dating to the Early Holocene (epi-Paleolithic culture) excavated from Gua Gunung Runtuh, Malaysia, is described. Cranial, dental, and limb bone measurements are recorded on the skeleton, and compared with early and modern skeletal samples from Southeast Asia and Australia. The comparisons demonstrate that the Gua Gunung specimen is most similar to Australian Aborigines in dental and limb measurements, while the cranial measurements indicate a close affinity to Mesolithic samples from Malaysia and Flores. These findings further suggest that the Gua Gunung skeleton, as well as other fossils from Tabon and Niah, are representative of an early group of people who occupied Sundaland during the late Pleistocene, and may be the ancestors of Australian Aborigines. Some of the dental and limb bone measurements exhibited by the ancestors persist in Southeast Asian populations until the early Holocene. Differences in cranial traits have, however, accumulated since the late Pleistocene in Australian Aborigines and early Southeast Asian peoples.
Matched MeSH terms: Bone and Bones/anatomy & histology*
Bone regeneration is a rapidly growing field that seeks to develop new biomaterials to regenerate bone defects. Conventional bone graft materials have limitations, such as limited availability, complication, and rejection. Glass ionomer cement (GIC) is a biomaterial with the potential for bone regeneration due to its bone-contact biocompatibility, ease of use, and cost-effectiveness. GIC is a two-component material that adheres to the bone and releases ions that promote bone growth and mineralization. A systematic literature search was conducted using PubMed-MEDLINE, Scopus, and Web of Science databases and registered in the PROSPERO database to determine the evidence regarding the efficacy and bone-contact biocompatibility of GIC as bone cement. Out of 3715 initial results, thirteen studies were included in the qualitative synthesis. Two tools were employed in evaluating the Risk of Bias (RoB): the QUIN tool for assessing in vitro studies and SYRCLE for in vivo. The results indicate that GIC has demonstrated the ability to adhere to bone and promote bone growth. Establishing a chemical bond occurs at the interface between the GIC and the mineral phase of bone. This interaction allows the GIC to exhibit osteoconductive properties and promote the growth of bone tissue. GIC's bone-contact biocompatibility, ease of preparation, and cost-effectiveness make it a promising alternative to conventional bone grafts. However, further research is required to fully evaluate the potential application of GIC in bone regeneration. The findings hold implications for advancing material development in identifying the optimal composition and fabrication of GIC as a bone repair material.
The effects of nicotine administration on bone-resorbing cytokines, cotinine, and bone histomorphometric parameters were studied in 21 Sprague-Dawley male rats. Rats aged 3 months and weighing 250-300 g were divided into three groups. Group 1 was the baseline control (BC), which was killed without treatment. The other two groups were the control group (C) and the nicotine-treated group (N). The N group was treated with nicotine 7 mg/kg body weight and the C group was treated with normal saline only. Treatment was given by intraperitoneal injection for 6 days/week for 4 months. The rats were injected intraperitoneally with calcein 20 mg/kg body weight at day 9 and day 2 before they were killed. ELISA test kits were used to measure the serum interleukin-1 (IL-1), interleukin-6 (IL-6), and cotinine (a metabolite of nicotine) levels at the beginning of the study and upon completion of the study. Histomorphometric analysis was done on the metaphyseal region of the trabecular bone of the left femur by using an image analyzer. Biochemical analysis revealed that nicotine treatment for 4 months significantly increased the serum IL-1, IL-6, and cotinine levels as compared to pretreatment levels. In addition, the serum cotinine level was significantly higher in the N group than in the C group after 4 months treatment. Histomorphometric analysis showed that nicotine significantly decreased the trabecular bone volume (BV/TV), trabecular thickness (Tb.Th), double-labeled surface (dLS/BS), mineralizing surface (MS/BS), mineral appositional rate (MAR), and bone formation rate (BFR/BS), while causing an increase in the single-labeled surface (sLS/BS), osteoclast surface (Oc.S/BS), and eroded surface (ES/BS) as compared to the BC and C groups. In conclusion, treatment with nicotine 7 mg/kg for 4 months was detrimental to bone by causing an increase in the bone resorbing cytokines and cotinine levels. Nicotine also exerted negative effects on the dynamic trabecular histomorphometric parameters.
Matched MeSH terms: Bone and Bones/anatomy & histology*; Bone and Bones/cytology; Bone and Bones/drug effects
This systematic review focuses on the management of two types of osseous defects, i.e. dehiscence and fenestration that arise during the placement of dental implant in the edentulous area (delayed implant placement). A systematic online search of main database from 1975 to 2009 was made. Five randomised controlled trials have been identified based on the inclusion criteria. Different management procedures were identified, in which guided bone regeneration procedure was most commonly advocated. Resorbable and non-resorbable m'embranes were compared, in which resorbable membrane was preferred as it caused less complicatiQn of membrane exposure or risk of infection. The benefit of using bone substitute along with membrane in rypairing bony defects cannot be concluded.