Bio-Medical Materials and Engineering - Volume 23, issue 5

Authors: Michailidis, N. | Karabinas, G. | Tsouknidas, A. | Maliaris, G. | Tsipas, D. | Koidis, P.

Article Type: Research Article

Abstract: Although dental implants exhibit only limited failure rates, their fracture is associated to major modifications of the prosthetic treatment and complex surgery for the removal of the remaining embedded implant part. This investigation aims to assess the developing stress fields in the bone–implant interface during mastication and asses the failure modes of oral implants. In order to achieve this, a FEM model of an implant was reverse engineered and virtually loaded at the top of the crown for a force spectrum ranging from 75–225 N in a vertical, horizontal and oblique occlusal direction. The calculated stress fields were compared …with clinically retrieved fractured implants with identical geometrical characteristics and the fracture modes of both cases were correlated. The developing stress patterns facilitated the interpretation of the implant failure as the maximum stresses, indicated critical values in both, lingual and buccal sides of the implant–bone interface at a certain critical level of bone resorption, in which failure occurs. Show more

Keywords: Peri-implant bone resorption, endosteal implant failure, FEM

DOI: 10.3233/BME-130756

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 317-327, 2013

Authors: Oe, Kenichi | Jingushi, Seiya | Iida, Hirokazu | Tomita, Naohide

Article Type: Research Article

Abstract: The purpose of this study was to assess the removability and biological reactivity of an ultrahigh molecular weight polyethylene (UHMWPE) fiber cable as a new biomaterial for osteosynthesis. We used a pull-out test and an implantation test to analyze the performance of the UHMWPE fiber cable using a dog model, and compared its characteristics with those of a wire cable and a soft wire. In the pull-out test, the UHMWPE fiber cable was as easy to remove as the soft wire, and both the UHMWPE fiber cable and the soft wire were significantly easier to remove than the wire cable. …The fixation capability and the biological reactivity of the UHMWPE fiber cable were examined in an osteosynthesis model of the dog greater trochanter, and were compared with those of the soft wire. The bone union rate, assessed radiographically, was very similar when using the UHMWPE fiber cable and the soft wire. However, in the soft wire group, both the surface of the greater trochanter under the fixation material and the penetration area around the fixation material showed an increased tendency toward a biological reaction, including inflammation and granulation tissue formation, as compared to the UHMWPE fiber cable group. The UHMWPE fiber cable was as easily removed from the bone tissue as the soft wire, and was easier to remove than the wire cable. Additionally, the UHMWPE fiber cable caused reduced biological reactivity with the surrounding tissue, as compared with the soft wire. In conclusion, the UHMWPE fiber cable appeared to be a suitable fixation material for osteosynthesis. Show more

Keywords: Ultrahigh molecular weight polyethylene fiber cable, biomaterials, osteosynthesis, greater trochanter osteotomy

DOI: 10.3233/BME-130757

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 329-338, 2013

Authors: Miyazaki, Toshiki | Mukai, Juntarou | Ishida, Eiichi | Ohtsuki, Chikara

Article Type: Research Article

Abstract: Apatite–polymer composites mimicking specific structure of natural bone are promised as bone substitutes with moderate flexibility able to be fabricated into desired shapes as well as bone-bonding bioactivity. In order to precipitate the apatite on polymer surfaces, aqueous processing using solution supersaturated to the apatite has been attracting as much attention. Polyglutamic acid (PGA) is a promised candidate of the polymer, since it has high apatite-forming ability owing to abundant carboxyl groups able to trigger the heterogeneous apatite nucleation. Although combination of PGA with different molecular weight is expected to provide design of organic–inorganic composites with moderate bioresorbability, precise relationship …between the molecular weight of the PGA and its apatite-forming ability has been remained unclear. In the present study, PGA hydrogels with different molecular weight were prepared by covalent cross-linking using ethylenediamine. Difference in apatite formation in simulated body fluid (SBF) was interpreted in terms of their chemical structure. It was found that hydrogels prepared from PGA with higher molecular weight showed tendency to have higher apatite-forming ability. It was attributed to high content of the carboxyl group remaining on the hydrogel due to low degree of the cross-linking. Show more

Keywords: Polyglutamic acid (PGA), apatite, simulated body fluid (SBF), molecular weight, organic–inorganic composites

DOI: 10.3233/BME-130758

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 339-347, 2013

Authors: Adalı, Terin

Article Type: Research Article

Abstract: Poly(methacrylates), namely 2-hydroxy ethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA) and triethylene glycol dimethacrylate (TEGDMA) were grafted onto chitosan by using ceric ammonium nitrate as a redox initiator. Semi-IPN gels of chitosan-graft-poly(HEMA)-graft-poly(EGDMA) and chitosan-graft-poly(HEMA)-graft-poly(TEGDMA) were obtained. The grafting conditions were optimized with respect to monomer concentrations. The products were characterized by TGA, FTIR, XRD and SEM techniques. The solubility of the grafted products in aqueous medium decreased with increasing grafting percentage. The insoluble gels exhibited a highly pH sensitive swelling behaviour. TGA thermograms showed that poly(HEMA)/poly(TEGDMA)-grafted product is much more stable than poly(HEMA)/poly(EGDMA)-grafted product showing that TEGDMA is a more …effective crosslinker than EGDMA. According to XRD analysis TEGDMA has a higher tendency to form ordered structures than EGDMA as it is capable of chain folding. The results of cytotoxicity studies revealed that the methacrylate-grafted chitosans were noncytotoxic and good candidates for biomedical applications. Show more

Keywords: Chitosan, grafting, poly(methacrylates), cytotoxicity, redox, biodegradability

DOI: 10.3233/BME-130759

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 349-359, 2013

Authors: Pajic-Lijakovic, Ivana

Article Type: Research Article

Abstract: The mechanism of micro-environmentally restricted hybridoma cell growth caused by action of local mechanical compression stress generated within various polysaccharide hydrogel matrixes is estimated by comparing the growth of hybridoma cells within (1) 1.5% Ca-alginate microbeads from Bugarski et al. [in: Fundamentals of Animal Cells Immobilization and Microencapsulation, M.F.A. Goosen, ed., CRC Press, Boca Raton, FL, 1993, p. 267] and (2) 1.3% alginate-agarose microbeads from Shen et al. [Animal Cell Technology: Basic & Applied Aspects, H. Murakami ed., Kluwer Academic Publishers, The Netherlands, 1992, p. 173]. Consideration of restricted cell growth dynamics based on developed kinetic model and kinetic …3D Monte Carlo simulation include: (1) changes the fraction of active proliferating cells in the exponential phase and (2) changes of non-proliferating cell concentration in the plateau phase. Higher value of the specific decrease of active fraction of proliferating cells κ is obtained for 1.3% alginate-agarose compared to 1.5% alginate microbeads. It corresponds to higher compression stress generated within hydrogel matrix during cell growth obtained for 1.3% alginate-agarose microbeads. Show more

Keywords: Immobilized cells, hydrogel, local compression stress, bioprocess design, modeling

DOI: 10.3233/BME-130760

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 361-371, 2013

Authors: Zhang, Shailin | Sun, Junying | Xu, Ying | Qian, Shi | Wang, Bing | Liu, Fei | Liu, Xuanyong

Article Type: Research Article

Abstract: Zirconia films were prepared on titanium by cathodic arc deposition technique. The surface topography and element composition of the films were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Osteoblast-like MG63 cells were cultured on the surface of the zirconia films in vitro, and cell behaviour was investigated, with titanium as control. The results obtained from scanning electron microscopy and immunofluorescence studies showed that the MG63 cells on ZrO2 films spread better than those on Ti. The CCK8 assay indicated that the zirconia films promoted the proliferation of MG63 cells. The results of alkaline phosphatase (ALP) activity …test and the expression of osteogenic marker genes, such as ALP, collagen I and osteocalcin, demonstrated that the differentiation of MG63 cells might be enhanced by zirconia films. In addition, the zirconia films possibly regulated osteoclastogenic gene expression by stimulating the expression of osteoprotegerin and reducing the expression of receptor activator of nuclear factor-kappaB ligand. The present work suggests that the ZrO2 film is worth further consideration for orthopedic implant applications. Show more

Keywords: Cathodic arc deposition, zirconia, film, osteoblast, osteogenesis

DOI: 10.3233/BME-130761

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 373-385, 2013

Authors: Hilal-Alnaqbi, Ali | Mourad, Abdel-Hamid I. | Yousef, Basem F. | Gaylor, John D.S.

Article Type: Research Article

Abstract: Bioartificial liver support provides a bridge to transplantation which is at present the only proven specific treatment for acute liver failure. In this paper, a novel multi-coaxial hollow fiber bioreactor so-called “Fibre-in-Fibre FIF Bioartificial liver device” with three compartments is experimentally and mathematically studied. The mathematical model in this paper is an extension of Krogh cylinder model for hollow fibre devices by including one more zone for oxygen transfer, i.e. oxygenation compartment. Three simultaneous linear differential equations were derived for pressure in plasma and cell compartments and flow rate in cell compartment. To validate the model, Oxygen Transfer Rate and …hydrostatic pressure experimental measurements for different flow rates, 17–400 ml/min, and different number of hollow fibres pairs are used. Several important parameters of the Michaelis–Menten was investigated, namely, constant Vmax  (the maximum oxygen consumption per unit volume of the cell mass), the oxygen partial pressure, the flow rate of the perfusate at device inlet. The results showed that the oxygenation compartment should easily secure Oxygen to the cells in compartment B. Show more

Keywords: Hepatocytes, artificial liver, bioartificial liver, fibre-in-fibre bioreactor, FIF bioreactor, bioreactor

DOI: 10.3233/BME-130762

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 387-403, 2013

Authors: Martín-López, Eduardo | Darder, Margarita | Ruiz-Hitzky, Eduardo | Nieto Sampedro, Manuel

Article Type: Research Article

Abstract: BACKGROUND: Spinal bridge implants are strategic to provide growth surfaces for axonal regeneration after spinal cord injuries. The design of an appropriate substrate, one that is suitable for implantation, must involve careful testing of the biomaterial properties both in vitro and in vivo. OBJECTIVE: The goal of this work was to test the structure, stability and biological response after spinal bridges implantation of several biopolymers, composed of mixtures of agar (AG), as structural matrix scaffold, with κ-carrageenan (Kc), gelatin (G), xanthan gum (Xn) and polysulfone (PS). METHODS: Biopolymer structures were studied by environmental scanning electron microscopy, whereas the …stability of gels was analyzed by in vitro degradation and swelling tests. The biocompatibility of these materials and their ability to promote cell growth and axonal regeneration were studied by implantation of spinal bridges containing empty linear channels in an acute rat spinal cord transection model at thoracic level (T8). RESULTS AND CONCLUSIONS: All gel mixtures gave rise to porous structures and they were stables to degradation, excepting the AG+G mixture. Spinal bridges constructed from all mixtures were implanted during a month in adult rats. After this time a low host reaction occurred to all bridge materials as well as neurite and cell ingrowths through the empty channels. Neurites within the bridges were mostly peripheral sensory fibers such as those positive for CGRP, whereas there was a lack of regeneration of central axons crossing from the spinal tissue to bridges. Many of these neurites established closed contacts with non-myelin Schwann cells. The histological analysis revealed a high accumulation of collagen fibers within the channels. Unexpected was the apparent loss of channels linearity which affected the growth of neurites and cells, indicating the need for additional regeneration strategies and vertebrae bridge fixing. Show more

Keywords: Agar, κ-carrageenan, gelatin, xanthan gum, polysulfone, axonal regeneration, spinal cord bridges

DOI: 10.3233/BME-130763

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 405-421, 2013

Authors: Pahlavan, Pedram | Najarian, Siamak | Afshari, Elnaz | Moini, Majid

Article Type: Research Article

Abstract: Artificial palpation is one of the most valuable achievements of artificial tactile sensing approach that can be used in various fields of medicine and more specifically in surgery. These techniques cause different surgical maneuvers to be done more precisely and noninvasively. In this study, considering the present problems and limitations of cross-clamping an artery during laparoscopic vascular surgeries, a new tactile sensory system will be introduced. Having imitated surgeon's palpation during open vascular surgeries and modeled it conceptually, the optimal amount of the total angular displacement of each robot joint in order to cross-clamping an artery without damaging to …the artery surrounding tissues will be calculated. The elastic governing equation of contact occurred between the tactile sensor placed on the first link of the robot and the surrounding tissues around the artery were developed. A finite element model is coupled with genetic algorithm optimization method so that the normal stress and displacements in contact surface of the robot and artery's surrounding tissues would be minimized. Thus, reliability and accuracy of artificial tactile sensing method in artery cross-clamping will be demonstrated. Finally, the functional principles of the new tactile system capable of cross-clamping an artery during laparoscopic surgeries will be presented. Show more

Keywords: Laparoscopic vascular surgeries, artificial tactile sensing, genetic algorithm optimization method

DOI: 10.3233/BME-130764

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 423-432, 2013

Authors: Xiao, Dongming | Yang, Yongqiang | Su, Xubin | Wang, Di | Sun, Jianfeng

Article Type: Research Article

Abstract: The load-bearing bone implants materials should have sufficient stiffness and large porosity, which are interacted since larger porosity causes lower mechanical properties. This paper is to seek the maximum stiffness architecture with the constraint of specific volume fraction by topology optimization approach, that is, maximum porosity can be achieved with predefine stiffness properties. The effective elastic modulus of conventional cubic and topology optimized scaffolds were calculated using finite element analysis (FEA) method; also, some specimens with different porosities of 41.1%, 50.3%, 60.2% and 70.7% respectively were fabricated by Selective Laser Melting (SLM) process and were tested by compression test. Results …showed that the computational effective elastic modulus of optimized scaffolds was approximately 13% higher than cubic scaffolds, the experimental stiffness values were reduced by 76% than the computational ones. The combination of topology optimization approach and SLM process would be available for development of titanium implants materials in consideration of both porosity and mechanical stiffness. Show more

Keywords: Topology optimization, selective laser melting (SLM), titanium implants materials, finite element analysis

DOI: 10.3233/BME-130765

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 5, pp. 433-445, 2013