Bio-Medical Materials and Engineering - Volume 27, issue 4
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: Background: Both Electrical Impedance Tomography (EIT) and Computed Tomography (CT) allow the estimation of the lung area. We compared two algorithms for the detection of the lung area per quadrant from the EIT images with the lung areas derived from the CT images. Methods: 39 outpatients who were scheduled for an elective CT scan of the thorax were included in the study. For each patient we recorded EIT images immediately before the CT scan. The lung area per quadrant was estimated from both CT and EIT data using two different algorithms for the EIT data. Results:…Data showed considerable variation during spontaneous breathing of the patients. Overall correlation between EIT and CT was poor (0.58–0.77), the correlation between the two EIT algorithms was better (0.90–0.92). Bland–Altmann analysis revealed absence of bias, but wide limits of agreement. Conclusions: Lung area estimation from CT and EIT differs significantly, most probably because of the fundamental difference in image generation.
Abstract: In this study, polyvinyl alcohol (PVA) and gelatin based cryogels were prepared by crosslinking chemically or physically for tissue engineering applications. Different PVA/Gelatin ratios (100:0, 90:10, 70:30, 50:50) and crosslinking methods have been used to prepare cryogels; chemical and physical structure of the prepared matrices were analysed by FTIR and SEM; swelling and degradation profiles were followed. Chemical and physical crosslinking was obtained by using glutaraldehyde as crosslinker and by applying freeze thawing cycle, respectively. Gelatin concentration and crosslinking method had significant effect on the pore size, swelling ratio and degradation profiles of the cryogels. Biocompatibility of the cryogels were…also investigated by MTT assay. SEM was used to investigate the cell morphology on the scaffolds. The MTT assay findings prove that physically crosslinked PVA/Gelatin scaffolds are more biocompatible and enhance more the adhesion and proliferation of mouse embryonic fibroblast cells (MEF) than chemically crosslinked PVA/Gelatin scaffolds. The overall results demonstrated that, the PVA/Gelatin cyrogels as a suitable biomaterial for tissue engineering applications and crosslinking methods affect the architecture and characteristic properties of the cryogels.
Abstract: Corrosion of surgical instruments provides a seat for contamination and prevents proper sterilisation, placing both patients and medical staff at risk of infection. Corrosion can also compromise the structural integrity of instruments and lead to mechanical failure in use. It is essential to understand the various factors affecting corrosion resistance of surgical instruments and how it can be minimised. This paper investigates the effect on corrosion resistance from the clinical washing decontamination (WD) process, specifically by studying the changes in surface roughness and Cr/Fe ratio. Results indicate that the WD process provides a positive effect on smooth polished samples,…while a lesser positive effect was observed on rough reflection reduced samples.
Abstract: Background: Chitosan is used in a wide field of applications and therapies and has been reported to be an effective hemostyptic. The objective of this study was to provide further information about the use of chitosan as a hemostyptic agent also taking into focus its hemocompatible effects. Methods: Human whole blood (n = 5 ) was anticoagulated with heparin, treated with different chitosan concentrations (0, 2.5, 5, 7.5, 10, 12.5, 25 mg/mL) and incubated at 37°C for 30 minutes. Before and after incubation different parameters for coagulation and hemocompatibility were evaluated. Results: Blood treated…with high chitosan concentrations showed enhanced coagulation, which we evaluated with activated clotting time, activated partial thromboplastin time and concentration of thrombin–antithrombin complexes. Furthermore, we observed an activation of blood platelets, complement cascade and granulocytes in the groups treated with chitosan. Conclusion: Our data indicate that chitosan activates human blood coagulation and hence has good properties as a hemostyptic agent. However, inflammatory parameters were upregulated after direct contact with human blood indicating that systemic administration of chitosans should not be performed whereas the topical use of chitosan as a hemostypticum should not present any hazard with regard to adverse inflammatory reactions at the site of application.
Keywords: Chitosan, hemostypticum, coagulation, hemocompatibility, platelets, complement system
Abstract: Background: Adhesive resin composite, which is used to bond orthodontic bracket to tooth surface is exposed to the influence of wear by tooth brushing and wear may influence loosening of the bracket. Objective: The aim of this study was to evaluate in vitro the effect of tooth brushing on the adhesion strength of orthodontic brackets bonded to surface treated porcelain. Method: A total of 90 glazed porcelain fused to metal facets (PFM) were randomly assigned into 3 groups according to the surface treatment to be received. Group 1 was conditioned with hydrofluoric acid (HF), group…2 conditioned with grit-blasting (GB) and group 3 conditioned with tribochemical silica coating (RC). The groups were evaluated for surface roughness (R a ) before and after surface treatment. Next, 15 samples from each group were subjected to brushing and remaining 15 samples served as the baseline (n = 15 ). Adhesion strength (shear bond strength)was recorded using a universal testing machine. Data collected were analyzed by ANOVA and Tukey’s multiple comparison post hoc analysis. Results: Tooth brushing decreased the bond strength in all groups. The highest adhesion strength (baseline and after brushing) was observed in group 3 (26.8 ± 1.77 MPa and 23.57 ± 1.02 MPa) and the lowest was found in group 1 (9.6 ± 1.5 MPa and 5.87 ± 0.77 MPa). Group 3 specimens exhibited the highest R a (1.24 ± 0.08). Conclusion: It was found that tooth brushing of the exposed adhesive resin composite at the bracket-bonding substrate interface lowers the bonding strength regardless of the surface treatment of the substrate.
Abstract: Orthodontic tunnel miniscrews with and without TiO2 nanotube arrays were fabricated to improve the induction of new bone formation and osseointegration. To inject the drug of recombinant human bone morphogenetic protein, tunnels in a conventional machined miniscrew were machined by a computer-numerical-control lathe. TiO2 nanotube arrays to load the drug were also formed on the surface of the tunnel miniscrew by anodic oxidation. To obtain clean TiO2 nanotube arrays, two-step anodic oxidation was conducted. The diameters of TiO2 nanotube window and TiO2 nanotube were ∼70 nm and ∼110 nm, respectively. Three groups, i.e., a conventional machined miniscrew,…a tunnel miniscrew without TiO2 nanotube arrays, and a tunnel miniscrew with TiO2 nanotube arrays, were prepared and inserted in the legs of five New Zealand White rabbits. In a histomorphometric analysis, the bone implant contact ratios of the tunnel miniscrews with the TiO2 nanotube arrays and without the TiO2 nanotube arrays were 5.84% and 5.88%, respectively. These values were higher than the value of 4.30% for the conventional machined miniscrew. The bone surface ratios in the tunnel miniscrew with and without the TiO2 nanotube were also higher than those of the conventional machined miniscrew. The measured values of the tunnel miniscrew with and without the nanotube and the conventional miniscrew were 76.75%, 73.41%, and 44.82%, respectively, although the differences were statistically insignificant. New bone at three weeks and six weeks after the operations were found in the tunnel miniscrews in fluorescent images. Both the tunnel miniscrews with and without the TiO2 nanotube arrays demonstrated greater bone formation compared to the conventional miniscrews. However, TiO2 nanotube arrays was not likely to provide additional benefit to the tunnel miniscrew. An in vivo study suggested that the tunnel fabricated in the miniscrew can be efficient drug-delivery systems to improve osseointegration.
Keywords: TiO2 nanotube arrays, orthodontics, miniscrew, drug delivery, in vivo
Abstract: Background: Vertical femoral neck fractures in the youth could be happened in high-energy accidents, and because of dominant shearing forces, this fracture is considered as a troublesome injury with a controversy regarding selection of the best fixation method. Objective: The long term goal of this quasi-experimental study was to find the more stable fixation method among cannulated screws (CSs), proximal femoral locking plate (PFLP), and dynamic hip screw with derotational screw (DHS+DS) for this kind of fracture. Methods: Twelve fresh-frozen cadaveric femurs were assigned to three groups that were matched for mean bone mineral density and…stiffness of intact bone. Vertical fractures were artificially mimicked in the specimens and fixed using three different implants, i.e. CSs, PFLP, and DHS+DS. Then, the samples were tested under incremental, cyclic, and failure loading phases. Results: The differences in all biomechanical parameters were statistically significant among tested groups (p < 0.05 ). All biomechanical parameters for the DHS+DS method of fixation are significantly different from those corresponding to CSs (p < 0.05 ). There were no significant differences in failure load and failure energy between the PFLP and CSs techniques (p > 0.05 ). Also, there were no significant differences in relative stiffness and femoral head displacement between the PFLP and DHS+DS groups (p > 0.05 ). Conclusions: Based on the clinical assumption that restricted weight-bearing regimen is recommended in the postoperative rehabilitation protocol, the results of this study suggest that the priority order of selection for the stable fixation implant of vertical femoral neck fracture in young patients is DHS+DS, then PFLP, and finally CSs.
Abstract: Background: Red blood cell (RBC) susceptibility to hemolysis – or fragility – can be profiled by subjecting a sample to progressive durations of mechanical stress and measuring hemolysis upon each. The ability to control stress application with multiple variable parameters can be useful in various areas of research. Bead milling, by oscillating an object in a blood sample, can offer control of parameters including oscillation force and frequency. Objective: This work addresses the role of bead shape and size, for a given container, in potentially creating qualitatively as well as quantitatively different fluidic stresses in the sample.…Methods: Identical, diluted RBC samples were stressed via bead milling using different beads, with other parameters the same. Resulting hemolysis was plotted for several time increments in each case. Results: For a cylindrical bead oscillating at a given frequency and force, bead length was a determinant of albumin’s protective effect on RBC, as reflected by mechanical fragility. Compared to a sphere of same diameter, the protective effect was absent with shorter cylinders, whereas for longer ones it appeared enhanced. Conclusions: Bead milling based RBC fragility testing could present a useful tool for creating, and studying effects of different shear stress types in inducing hemolysis.
Abstract: Existing scaffolds cannot adequately satisfy the simultaneous requirements for the regeneration of bone. The challenge remains of how to improve the integration of newly formed bone with the surrounding tissues. The purpose of this study was to investigate the effects of two silk fibroin scaffolds, a hexafluoro isopropanol-based silk fibroin (HFIP-F) and an aqueous-based silk fibroin (A-F), for their osteoinductive potentials in large critical size bone defects in vivo. β -tricalcium phosphate (β -TCP) was used as a positive control. After implantation into defects created in the knee joints of rabbits for 1 and 2 weeks, hematoxylin and eosin (H-E)…and Azan staining revealed that the A-F scaffold as well as β -TCP had stronger osteoinductive ability than the HFIP-F scaffold. The A-F scaffold exhibited prominent areas of neo-tissue containing bone-like nodules. Furthermore, induced osteointegration was observed between native and neo-tissue within the osteo defects in the knee joints of rabbits. Immunohistochemical staining showed the highest expression of Runx2, BMP-2, BMP-7, Smad1/5/9 and Phospho-Smad in the A-F scaffold implants. Osteoinduction of the porous A-F scaffold might be influenced by the amount of BMP signaling present in the local microenvironment in the implants. This study opens a new avenue to use A-F silk fibroin scaffolds for the regeneration of bone defects.
Keywords: Silk fibroin, surface morphology, scaffold, β-TCP, bone regeneration
Abstract: Bioactive glass (BG)-containing fiber-reinforced composite implants, typically screw-retained, have started to be used clinically. In this study, we tested the mechanical strength of composites formed by a potential implant adhesive of n-butyl-2-cyanoacrylate glue and BG S53P4 particles. Water immersion for 3, 10 or 30 days had no adverse effect on the compression strength. When cyanoacrylate glue-BG-composites were subjected to simulated body fluid immersion, the average pH rose to 7.52 (SD 0.066) from the original value of 7.35 after 7 days, and this pH increment was smaller compared to BG particle-group or fibrin glue-BG-composite group. Based on these results n-butyl-2 cyanoacrylate…glue, by potentially producing a strong adhesion, might be considered a possible alternative for fixation of BG S53P4 containing composite implants. However, the mechanical and solubility properties of the cyanoacrylate glue may not encourage the use of this tissue adhesive with BG particles.