Structure Of Human Bone Research Articles

Humanized In Vivo Bone Tissue Engineering: In Vitro Preculture Conditions Control the Structural, Cellular, and Matrix Composition of Humanized Bone Organs.

Bone tissue engineering (BTE) has long sought to elucidate the key factors controlling human/humanized bone formation for regenerative medicine and disease modeling applications, yet with no definitive answers due to the high number and co-dependency of parameters. This study aims to clarify the relative impacts of in vitro biomimetic 'preculture composition' and 'preculture duration' before in vivo implantation as key criteria for the optimization of BTE design. These parameters are directly related to in vitro osteogenic differentiation (OD) and mineralization and are being investigated across different osteoprogenitor-loaded biomaterials, specifically fibrous calcium phosphate-polycaprolactone (CaP-mPCL) scaffolds and gelatin methacryloyl (GelMA) hydrogels. The results show that OD and mineralization levels prior to implantation, enhanced by a mineralization medium supplement to the osteogenic medium (OM), significantly improve ectopic BTE outcomes, regardless of the biomaterial type. Specifically, preculture conditions are pivotal in achieving more faithful mimicry of human bone structure, cellular and extracellular matrix composition and organization, and provide control over bone marrow composition. This work emphasizes the potential of using biomimetic culture compositions, specifically the addition of a mineralization medium as a cost-effective and straightforward approach to enhance BTE outcomes, facilitating rapid development of bone models with superior quality and resemblance to native bone.

Polyacrylonitrile‒Chitosan IPN composite scaffolds that closely mimic the human trabecular bone structure for tissue engineering

Successful bone tissue engineering involves managing several important parameters, such as the design of intercommunicating porous structures, pore sizes, and the material and mechanical suitability of the material. In our work, we focused on the preparation of a synthetic scaffold that morphologically mimics the structure of human trabecular bone. The scaffolds were fabricated through the thermal modification (TM) of polyacrylonitrile. The scaffold strength was supported by a crosslinked chitosan supporting network. The prepared scaffold has imprinted pores of the appropriate size to facilitate the ingrowth and proliferation of human osteoblasts throughout the entire pore volume created by a primary porogen, sodium chloride. The resulting material has a dual porous morphological structure, in which adjustable larger pores support cellular ingrowth into the scaffold, whereas smaller pores, created using succinonitrile (SCN) as a secondary porogen, increase the diffusion of oxygen and nutrients to developing cells. The mechanical properties of the scaffold were promoted by the use of a secondary interpenetrating network (IPN) based on chitosan. The incorporation of secondary IPNs led to a significant improvement in the mechanical characteristics of the scaffold. Two crosslinking agents were used: the widely utilized glutaraldehyde (GA) and its green, nontoxic alternative, genipin (GEN).The current study introduces a synthetic scaffold that effectively mimics the structure of human trabecular bone, providing a conducive environment for osteoblast proliferation and ingrowth. We incorporated a dual porous morphology and a secondary IPN based on chitosan and found that the scaffold exhibited improved mechanical properties and nutrient diffusion capabilities. This research highlights the potential of these scaffolds for major advancements in bone tissue engineering, demonstrating their noncytotoxic nature and ability to support the adhesion and proliferation of the human osteosarcoma cell line SAOS-2. The described scaffold preparation technique may offer distinct advantages over current high-end methods such as 3D printing. The primary benefit lies in its very simple instrumentation, which enables the creation of a complex trabecular bone morphology with both macro- and microporosity in the bulk, which is still challenging for common 3D printers. Additionally, IPN with chitosan can be postmodified, substantially expanding the potential applications of these scaffolds.

Preliminary study on the preparation of antler powder/chitosan/β-glycerophosphate sodium/polyvinyl alcohol porous hydrogel scaffolds and their osteogenic effects.

Introduction: The production of bone-like structural scaffolds through bone tissue engineering technology is a promising method for bone regeneration to repair bone defects. Deer antler, an easily harvested and abundantly sourced initial bone tissue structure, resembles the composition and structure of human cancellous bone and can serve as a new material for allogeneic bone transplantation. Methods: This study involved the preparation and characterization of antler powder/chitosan/β-glycerophosphate sodium/polyvinyl alcohol (AP/CS/β-GP/PVA) porous hydrogel scaffolds to verify their material properties and osteogenic mechanisms. The microstructure, hydrophilicity, and mechanical properties of the scaffolds were studied using Scanning Electron Microscopy (SEM), contact angle measurement, and a universal material testing machine. The interactions between the various components were investigated using Fourier-Transform Infrared Spectroscopy (FTIR). Biocompatibility, osteogenic properties, and expression of osteogenesis-related proteins of the scaffolds were evaluated through Cell Counting Kit-8 (CCK-8) assays, alkaline phosphatase staining, Alizarin Red staining, live/dead cell staining, and Western blot analysis. Results: The results showed that as the content of deer antler powder increased, both the hydrophilicity and mechanical properties of the scaffold materials improved, while the porosity slightly decreased with an increase in deer antler powder content. Cell culture experiments demonstrated that scaffolds with a higher proportion of deer antler powder were beneficial for the proliferation and differentiation of mouse pre-osteoblast (MC3T3-E1) cells, with the scaffolds containing 10% and 8% deer antler powder showing the best effects. The upregulation of RUNX2, OCN, OSX, and OPN protein expression may promote differentiation. Discussion: Therefore, the AP/CS/β-GP/PVA hydrogel scaffolds have the potential to become a promising biomaterial for bone tissue engineering.

Mechanical properties of hierarchical porous lattices with microscopic porosity fabricated by combination of lattice design and HSSH process

The hierarchical porous lattice implant with microscopic porosity, which resembles the original human bone structure, has significant potential application value. The microscopic porosity in the hierarchical porous lattice implant plays a crucial role in transporting nutrients and promoting tissue regeneration. However, it is difficult to fabricate microscopic pores smaller than 200 μm by powder bed fusion (PBF) processes due to the limitations of the laser spot size. In this study, the preparation of a hierarchical porous lattice implant with microscopic porosity is proposed by coupling structure design with the high scanning speed - short hatch spacing (HSSH) process formation. The structure-versus-process relationship is used to control the size and distribution of the microscopic pores, which meets the requirements of modulus and high biocompatibility. This proposed process breaks the inherent law where the higher the porosity, the higher the modulus of the lattice for the same lattice type. The modulus and porosity of the hierarchical porous implants could be flexibly tuned over a wide range (0.1–1.8 GPa and 63–84 %, respectively). The microscopic porosity is mainly distributed near the contour of the core rod, and the macroscopic porosity and microscopic porosity are approximately 73.70 % and 8.22 %, respectively. The problem of large errors in fitting the hierarchical porous lattice modulus calculation model according to the Gibson-Ashby equation has been solved. The mechanism of microscopic porosity formation was also analyzed. Furthermore, this method has the advantage of universal applicability, providing a feasible way for the development and application of porous materials.

Correlation between Malocclusion and Mandibular Fractures: An Experimental Study Comparing Dynamic Finite Element Models and Clinical Case Studies.

Mandibular fractures are very common in maxillofacial trauma surgery. While previous studies have focused on possible risk factors related to post-operative complications, none have tried to identify pre-existing conditions that may increase the risk of mandibular fractures. We hypothesized, through clinical observation, that anatomical conditions involving poor dental contacts, such as malocclusions, may increase the risk of mandibular fractures. This work was subdivided into two parts. In the first part, Digital Imaging and Communications in Medicine (DICOM) data of four healthy patients characterized by different dentoskeletal occlusions (class I, class II, class III, and anterior open bite) have been used to develop four finite element models (FEMs) that accurately reproduce human bone structure. A vertical and lateral impact have been simulated at increasing speed on each model, analyzing the force distribution within the mandibular bone. Both vertical and lateral impact showed higher level of stress at the impact point and in the condylar area in models characterized by malocclusion. Specifically, the class III and the open bite models, at the same speed of impact, had higher values for a longer period, reaching critical stress levels that are correlated with mandibular fracture, while normal occlusion seems to be a protective condition. In the second part of this study, the engineering results were validated through the comparison with a sample of patients previously treated for mandibular fracture. Data from 223 mandibular fractures, due to low-energy injuries, were retrospectively collected to evaluate a possible correlation between pre-existing malocclusion and fracture patterns, considering grade of displacement, numbers of foci, and associated CFI score. Patients were classified, according to their occlusion, into Class I, Class II, Class III, and anterior open bite or poor occlusal contact (POC). Class I patients showed lower frequencies of fracture than class II, III, and open bite or POC patients. Class I was associated with displaced fractures in 16.1% of cases, class II in 47.1%, class III in 48.8% and open bite/POC in 65.2% of cases (p-value < 0.0001). In class I patients we observed a single non-displaced fracture in 51.6% of cases, compared to 12.9% of Class II, 19.5% of Class III and 22.7% of the open bite/POC group. Our analysis shows that class I appears to better dissipate forces applied on the mandible in low-energy injuries. A higher number of dental contacts showed a lower rate of multifocal and displaced fractures, mitigating the effect of direct forces onto the bone. The correlation between clinical data and virtual simulation on FEM models seems to point out that virtual simulation successfully predicts fracture patterns and risk of association with different type of occlusion. Better knowledge of biomechanics and force dissipation on the human body may lead to the development of more effective safety devices, and help select patients to plan medical, orthodontic/dental, and/or surgical intervention to prevent injuries.

Drug-Releasing Tannic Acid-Mediated Adhesive PEG Hydrogel for Porous Titanium Implants.

Porous titanium implants are commonly utilized for orthopedic surgery because they can mimic the mechanical properties and porous structure of human bone. However, the bioinertness of titanium (Ti) has been reported to obstruct biointegration processes, resulting in slower bone repair. Here, we propose a localized drug delivery system on Ti surfaces using adhesive hydrogel to enhance biological-Ti interactions. The hydrogel was fabricated from polyethylene glycol (PEG), which was cross-linked by the complex of tannic acid (TA) and 1,4-phenylenediboronic acid (PDBA) and stabilized by bovine serum albumin (BSA). The hydrogel was formed and attached to a Ti plate to investigate stability, biodegradability, controlled drug release, and biocompatibility. The stability and biodegradability of the hydrogel could be tuned by adjusting the concentrations of BSA and TA. The hydrogel lasted and remained adhered to the Ti surface after being submerged in PBS for at least 15 days. The controlled release of strontium ranelate (SrRan) and the release mechanism depended on the amount of TA since it was found to govern the hydrogel integrity and pore size. Additionally, in vitro biocompatibility was validated using L929 fibroblast and MC3T3-E1 osteoblast cells that showed greater than 70% viability. The adhesive hydrogel was further studied by injecting it into a 3D-printed Ti-scaffold that contained a porous structure mimicking natural human bone. The hydrogel completely filled and adhered to the inner porous structure of the scaffold. The biodegradation and drug release of the hydrogel in the scaffold occurred at a slower rate, suggesting sustainable drug release that is suitable for bone cell regeneration. The overall results in biodegradability, controlled drug release, and biocompatibility demonstrate the great potential of the drug-releasing TA-mediated adhesive PEG hydrogel as a Ti-enhancing biomaterial that supports osseointegration.

Medical simulator for the training of radiologists: experimental work

BACKGROUND: Ankle injuries of various nature bruises, sprains, tears, dislocations and subluxations, and fractures account for 2030% of all musculoskeletal system injuries. The most common ankle injuries are a tear and sprain. The difficulty in treating fractures in this location is due to the need for accurate repositioning of the articular surface and stable fixation of fragments. The actual task is to train roentgenologists in the field. The inclusion of medical personnel in the educational process at all levels of training simulation courses aids in the reduction of errors, reduction of problems, and the improvement of the quality of medical treatment provided to the public.&#x0D; OBJECTIVE: This study aims to develop and create a simulator that simulates human bone structure and soft tissues and allows roentgenologists to get through training and instruction radiological examinations of an ankle joint and a foot.&#x0D; MATERIALS AND METHODS: The following stages of the simulators development have been completed: acquiring ankle bone samples, creating a mold for casting, and constructing the simulator. The results of computer and magnetic resonance imaging were used to construct bone samples, from which a computerized 3D model of the bones of the foot and ankle joint was obtained. Using additive technologies, anatomically correct reproductions of human foot and ankle bones were made. At the next stage, a three-dimensional digital model was developed, and a mold for casting the finished product was made. Bone samples collected in a single structure were placed inside the mold. Next, a step-by-step filling of the form with a soft gel-like material was performed. In this case, a self-vulcanizing silicone rubber composition is selected, which, after solidification, imitates human soft tissues.&#x0D; RESULTS: During the course of the study, a prototype medical simulator was created that models human bone structure and soft tissues and allows roentgenologists to practice performing ankle joint and foot roentgenography.&#x0D; CONCLUSION: Because of its high anatomical accuracy, ease of use, and mass production potential, the developed simulator can be widely employed in the teaching of roentgenologists.

Hydroxyapatite microspheres used as a drug delivery system for gliosarcoma strain 9l/Lacz treatment by photodynamic therapy protocols

BackgroundHydroxyapatite (HAp) presents similarities with the human bone structure and presents properties such as biodegradability, biocompatibility, and osteoconductivity, which favors its use in prostheses implants and enables its use as a vehicle for the delivery of photosensitizers (PS) from systems of release (DDS) for photodynamic therapy applications Methods: In this work was to synthesized hydroxyapatite microspheres (meHAp), encapsulated with chloroaluminium phthalocyanine (ClAlPc), for DDS. meHAp was synthesized using vaterite as a template. The drug was encapsulated by mixing meHAp and a 50.0 mg.mL−1 ClAlPc solution. Photochemical, photophysical, and photobiological studies characterized the system. Results: The images from the SEM analysis showed the spherical form of the particles. All spectroscopic results showed excellent photophysical parameters of the drug studied when served in the meHAp system. The incorporation efficiency was 57.8 %. The trypan blue exclusion test results showed a significant reduction (p < 0.05) in cell viability for the groups treated with PDT at all concentrations above 250 μg.mL−1. In 9 L/lacZ gliosarcoma cells, PDT mediated at concentrations from 250 to 62.5 µg.mL−1 reduced cell viability by more than 98 %. In the cell internalization study, it was possible to observe the internalization of phthalocyanines at 37 °C, with the accumulation of PS in the cytoplasm and inside the nucleus in the two tested concentrations. Conclusions: From all the results presented throughout the article, the meHAp system shows promise for use as a modified release system (DSD) in photodynamic therapy.

Structural and topological design of conformal bilayered scaffolds for bone tissue engineering

A fundamental outcome of bone tissue engineering is the regeneration of bone defects presenting large dimensions. A promising solution in biomedical practice is the implantation of biomimetic scaffolds, i.e. porous structures mimicking the natural shapes of healthy bone tissues, which are colonized by mesenchymal stem cells and that support the growth of the regenerating tissues, until the complete healing process is realized. This work presented a workflow for the geometrical modeling and the mechanical design of beam-based, bilayered, and conformal scaffolds, mimicking the human cortico-cancellous bone structure for filling a large dimension defect in the mandibular bone of an injured patient. An isotropic Voronoi topology built on a refined point set generated by a high-quality meshing algorithm was adopted for lattice generation, which led to an open-cell architecture characterized by full connectivity and uniform cell size. Such geometrical and structural features represent crucially important requirements for maximizing the osteointegration and the vascularization of the implanted scaffold. An irregular scaffold was modelled, including a cortical and a sponge layer. The beam radii of both layers were determined by matching the elastic properties of the corresponding bone tissues, thus minimizing the stress shielding effects. Interestingly, several scaffold properties deriving from the proposed procedure, such as the porosity and the pore size, were in good agreement with those reported in the literature.

Is Corticalization in Radiographs Related to a Higher Risk of Bone Loss around Dental Implants in Smoking Patients? A 5-Year Observation of Radiograph Bone-Texture Changes.

Currently, the topic of dental implants is widely researched. However, still compromising are the factors that can affect implant loss as a consequence of marginal bone loss. One of the factors is smoking, which has a devastating effect on human health and bone structure. Oral health and jaw condition are also negatively affected by smoking. The aim of this study was to evaluate the peri-implant jawbone corticalization phenomenon in tobacco smokers. A total of 2196 samples from 768 patients with an implant in the neck area were checked, and texture features were analyzed. The corticalization phenomenon was investigated. All analyses were performed in MaZda Software. The influence of corticalization was investigated as a factor on bone structure near the implant neck. The statistical analysis included a feature distribution evaluation, mean (t-test) or median (W-test) comparison, analysis of regression and one-way analysis of variance or Kruskal-Wallis test as no normal distribution or between-group variance was indicated for the significant differences in the investigated groups. Detected differences or relationships were assumed to be statistically significant when p < 0.05. The research revealed that MBL was correlated with smoking after 5 years (0.42 mm ± 1.32 mm 0 mm ± 1.25 mm), the Corticalization Index was higher in the smoker group on the day of surgery, and it became higher after 5y of observation (185.98 ± 90.8 and 243.17 ± 155.47). The implant-loss frequency was higher in the group of smokers, too, compared to non-smokers (6.74% and 2.87%). The higher the torque value during the implant placement, the higher the Corticalization Phenomenon Index. The research revealed a correlation between smoking and changes in bone structure in radio textures near the implants. The corticalization phenomenon is important, may be detected immediately after implant placement and may be one of the indicators of the implant success rate.

Improved Biocompatibility and Angiogenesis of the Bone Titanium Scaffold through ERK1/2 Signaling Mediated by an Attached Strontium Element.

The promotion of early osseointegration is crucial for the success of biomedical titanium implants. Physical and chemical modifications to the material surface can significantly compensate for the lack of biocompatibility and early osseointegration of the implant. In this study, we implanted strontium onto titanium plates and analyzed the effect of strontium-doped materials on angiogenesis and biocompatibility in the human bone structure. Our findings demonstrated that strontium-loaded titanium sheet materials effectively promote human umbilical vein endothelial cell (HUVEC) biocompatibility and vascular differentiation ability, as evidenced by proliferation-apoptosis assays, RT-qPCR for vascular neogenesis markers, ELISA for vascular endothelial growth factor (VEGF) levels, and nitric oxide (NO) analysis. Mechanism studies based on RNAseq and Western blotting analysis revealed that strontium can promote titanium material biocompatibility with HUVEC cells and vascular neovascularization ability by activating the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. Meanwhile, blocking the ERK1/2 signaling pathway could reverse the promotional effect of vascular formation. Overall, we have successfully fabricated a multifunctional biocompatible bone implant with better histocompatibility and angiogenesis compared to uncoated implants.

Design and Development of 3D-Printed Personalized Femoral Prosthesis Technologies

The femur supports the entire body weight, and any damage or necrosis to this bone can significantly impair normal walking. Therefore, repairing the femur is essential to restoring its function. However, due to variations in human bone structure, standardized prostheses often deliver poor repair outcomes. We used the medical three-dimensional (3D) auxiliary software Mimics to design personalized femoral prostheses to address this issue. The femoral prosthesis filler was porous, and all aspects of the prosthesis were thoroughly studied and analyzed before direct molding using 3D printing technology. The personalized femoral prosthesis filler and bone plate designed using 3D printing technology have positive effects, and the matching between the femoral prosthesis, bone plate, and filler is satisfactory. The pore structure of the 3D-printed femoral prosthesis filler and the bone plate is clear and of high quality, which shortens the research and development cycle and reduces costs, providing a foundation for the direct application of 3D-printed personalized prostheses.

Additive manufacturing of complex-shaped and porous silicon nitride-based components for bionic bones

Si3N4 is a novel implant material with promising applications in the replacement of human hard tissues. The biomimetic human bone structure used in this study was created using digital light-processing technology. The effect of pore-forming agent content on the curing and mechanical properties of Si3N4 ceramics was studied. The obtained results indicated that with an increase in the pore-forming agent content, the cure depth of the ceramic suspension first increased and then decreased, while the excess cure width decreased. Furthermore, as the pore-forming agent content increased, the porosity of the sample increased, whereas the compressive strength and Young's modulus decreased. The maximum porosity of the sample at the optimal mass ratio (pore-forming agent: Si3N4 = 5:10) is 58.48 ± 0.49%, and the compressive strength and Young's modulus are 79.01 ± 6.78 MPa and 18.18 ± 0.26 GPa, respectively.

Design and Geometric Characterization of Three-Dimensional Gradient Heterogeneous Bone Tissue Structures Based on Voronoi

Bone tissue is one of the most transplanted tissues. During transplantation, additive manufacturing enables fast and efficient production and fabrication of shaped external implants, and designing porous interconnected bionic external implants is the focus and difficulty of bone tissue engineering. Based on Voronoi geometry to design a bone tissue structure with hole position gradient—Voronoi gradient structure (VFGM, Voronoi functional gradient materials), the design hole center conforms to the uniform gradient probability spatial distribution, and the boundary in 3D Voronoi is calculated with the hole center as the bone trabecular skeletal. It can be used to design a variety of heterogeneous structures to match with the damaged location. The heteromorphic VFGM structure is highly similar to the human bone structure and can provide geometric design for bone tissue engineering external implants.

369Fabrication of 3D gel-printed β-tricalcium phosphate/titanium dioxide porous scaffolds for cancellous bone tissue engineering.

Human bone is composed of cortical bone and cancellous bone. The interior portion of natural bone is cancellous with a porosity of 50%-90%, but the outer layer is made of dense cortical bone, of which porosity was not higher than 10%. Porous ceramics were expected to be research hotspot in bone tissue engineering by virtue of their similarity to the mineral constituent and physiological structure of human bone. However, it is challenging to utilize conventional manufacturing methods to fabricate porous structures with precise shapes and pore sizes. Three-dimensional (3D) printing of ceramics is currently the latest research trend because it has many advantages in the fabrication of porous scaffolds, which can meet the requirements of cancellous bone strength, arbitrarily complex shapes, and individualized design. In this study, β-tricalcium phosphate (β-TCP)/titanium dioxide (TiO2) porous ceramics scaffolds were fabricated by 3D gel-printing sintering for the first time. The chemical constituent, microstructure, and mechanical properties of the 3D-printed scaffolds were characterized. After sintering, a uniform porous structure with appropriate porosity and pore sizes was observed. Besides, biological mineralization activity and biocompatibility were evaluated by in vitro cell assay. The results demonstrated that the incorporation of TiO2 (5 wt%) significantly improved the compressive strength of the scaffolds, with an increase of 283%. Additionally, the in vitro results showed that the β-TCP/TiO2 scaffold had no toxicity. Meanwhile, the adhesion and proliferation of MC3T3-E1 cells on scaffolds were desirable, revealing that the β-TCP/TiO2 scaffolds can be used as a promising candidate for repair scaffolding in orthopedics and traumatology.

Surface modification of coral skeleton derived nanohydroxyapatite using polymers and its in-vitro studies for bone substitute applications

Reprocessing waste things into a functional product gives two-edged benefits, an eco-friendly environment and waste management. Nowadays, Ceramic materials based on calcium phosphates, which include Nanohydroxyapatite (nHAp) and Tri-calcium Phosphates (TCP) were extensively used in biomedical applications for their outstanding biocompatibility and bioactivity properties. In this work, nHAp (pure) and its polymeric composites were prepared through the precipitation method using the coral skeleton as a calcium precursor. Besides, to change the surface functional characteristics, the polymers were utilized as a capping agent. The synthesized samples were examined by spectrographic tools such as XRD, FT-IR, SEM/EDAX, TG-DTA, XPS and HR-TEM to find the phase, functional groups, size, morphology and thermal stability together with phase transition as well as bonding types which present in the prepared samples respectively. In addition, Simulated Body Fluid (SBF) analysis, antimicrobial assay and hemolytic test were intended to test the apatite-forming ability, antimicrobial effectiveness and hemocompatibility of the prepared samples. Therefore, the present findings suggest the possibility of developing novel HAp polymeric nanocomposites that exhibit improved biocompatible, osteoconductive which impersonates the structure of natural human bone. So, that can use for making bone and dental implants using corals skeleton as a precursor at a lesser cost.

Review of Physical, Mechanical, and Biological Characteristics of 3D-Printed Bioceramic Scaffolds for Bone Tissue Engineering Applications.

This review focuses on the advancements in additive manufacturing techniques that are utilized for fabricating bioceramic scaffolds and their characterizations leading to bone tissue regeneration. Bioscaffolds are made by mimicking the human bone structure, material composition, and properties. Calcium phosphate apatite materials are the most commonly used scaffold materials as they closely resemble live bone in their inorganic composition. The functionally graded scaffolds are fabricated by utilizing the right choice of the 3D printing method and material combinations to achieve the requirement of the bioscaffold. To tailor the physical, mechanical, and biological properties of the scaffold, certain materials are reinforced, doped, or coated to incorporate the functionality. The biomechanical loading conditions that involve flexion, torsion, and tension exerted on the implanted scaffold are discussed. The finite element analysis (FEA) technique is used to investigate the mechanical property of the scaffold before fabrication. This helps in reducing the actual number of samples used for testing. The FEA simulated results and the experimental result are compared. This review also highlights some of the challenges associated while processing the scaffold such as shrinkage, mechanical instability, cytotoxicity, and printability. In the end, the new materials that are evolved for tissue engineering applications are compiled and discussed.

Morphological Integrated Preparation Method and Implementation of Inorganic/Organic Dual-Phase Composite Gradient Bionic Bone Scaffold.

Large bone defects caused by congenital deformities and acquired accidents are increasing day by day. A large number of patients mainly rely on artificial bone for repair. However, artificial bone cannot fully imitate the structure and composition of human bone, resulting in a large gap with autologous bone function. Therefore, this article proposes a continuous preparation method for inorganic/organic biphasic composite gradient biomimetic bulk bone scaffolds. First, a controllable gradient hybrid forming platform for inorganic/organic dual-phase biomaterials was constructed, and the feeding control strategy was studied to achieve precise control of the feeding of sodium alginate/gelatin composite organic materials and hydroxyapatite inorganic materials. The speed is, respectively, sent from the corresponding feeding nozzle to the mixing chamber to realize the uniform mixing of the biphasic material and the extrusion of the composite material, and the inorganic/organic biphasic composite gradient biomimetic bone scaffold with gradual structure and composition is prepared. Second, to prove the superiority of the preparation method, the physicochemical and biological properties of the prepared scaffolds were evaluated. The test results showed that the morphological characteristics of the biphasic composite gradient bone scaffold showed good microscopic porosity and the structure and composition showed gradients. The mechanical properties are close to that of human bone tissue and in vitro cell experiments show that the scaffold has good biocompatibility and bioactivity. In conclusion, this article provides a new type of bone scaffold preparation technology and equipment for the field of tissue engineering, which has research value and application prospects.

Design of a Novel Trabecular Acetabular Cup and Selective Laser Melting Fabrication.

The acetabular cups used in total hip arthroplasty are mostly made of dense metal materials with an elastic moduli much higher than that of human bone. This leads to stress shielding after implantation, which may cause aseptic loosening of the implant. Selective laser melting (SLM) technology allows us to produce tiny and complex porous structures and to reduce the elastic moduli of dense metals, thereby avoiding stress shielding. In the present study, rhombic dodecahedron porous structures with cell sizes of 1 mm, 1.5 mm, and 2 mm were designed. The strut diameter was changed to ensure that the porosity and pore size would meet the bone ingrowth requirements. Then, porous Ti6Al4V alloy specimens were printed using SLM, and compressive tests were carried out. The results showed that the compressive strength and elastic modulus values of the specimens with a cell size of 1.5 mm were in the range of 78.16–242.94 MPa and 1.74–4.17 GPa, respectively, which are in line with the mechanical properties of human cortical bone. Finite element analysis of a total hip joint model was carried out to simulate gait, and the surface of the trabecular acetabular cup was divided into 10 regions according to the stress distribution, with the stress interval in the range of 37.44–219.24 MPa. According to the compression test results, the gradient structure of Ti6Al4V alloy with different porosity was designed for trabecular coating. The gradient porous structure meets the mechanical requirements and is closer to the natural structure of human bone than the uniformly distributed porous structure.

P-65934199-236 - The segmentation of the mandible with convolutional neuronal networks for preoperative 3D-planning

Objectives Multiple sophisticated automatic and semi-automatic techniques for human bone structure segmentation in CT scans have been developed in order to simplify and speed up diagnostic tasks, for example, preoperative planning and 3D-printing. We created a segmentation method based on convolutional neuronal networks (CNN) for surgical mandible 3D planning and 3D-Printing. In this study we investigated the accuracy of a neuronal network bases segmentation method. Methods Facial CTs at the Inselspital, Bern University Hospital (Switzerland) were used. The segmentation of 106 mandibles was performed manually. These 106 datasets were then divided into a training set, consisting of 96 CT scans, and a validation set with 10 CT scans. Three different, modified CNN were trained to recognize and segment the mandible using the training set. The trained networks then analyzed the test data set. These Results were then compared with the manually segmented data. Results The neural network was able to identify the mandible in all 10 different test data sets. We found an average dice coefficient of 0.961 with an accuracy of 0.999. Conclusion The results show that a trained CNN has developed an amazing ability to recognize anatomical structures such as the jaw in a CT data set. The upper and lower jaw are separated automatically. We observed that artefacts were filtered out by the neural network. This can and will greatly simplify the preparation of data sets for 3D planning and 3D printing. Multiple sophisticated automatic and semi-automatic techniques for human bone structure segmentation in CT scans have been developed in order to simplify and speed up diagnostic tasks, for example, preoperative planning and 3D-printing. We created a segmentation method based on convolutional neuronal networks (CNN) for surgical mandible 3D planning and 3D-Printing. In this study we investigated the accuracy of a neuronal network bases segmentation method. Facial CTs at the Inselspital, Bern University Hospital (Switzerland) were used. The segmentation of 106 mandibles was performed manually. These 106 datasets were then divided into a training set, consisting of 96 CT scans, and a validation set with 10 CT scans. Three different, modified CNN were trained to recognize and segment the mandible using the training set. The trained networks then analyzed the test data set. These Results were then compared with the manually segmented data. The neural network was able to identify the mandible in all 10 different test data sets. We found an average dice coefficient of 0.961 with an accuracy of 0.999. The results show that a trained CNN has developed an amazing ability to recognize anatomical structures such as the jaw in a CT data set. The upper and lower jaw are separated automatically. We observed that artefacts were filtered out by the neural network. This can and will greatly simplify the preparation of data sets for 3D planning and 3D printing.