Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 43

Abstract: Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

Abstract: The aim of this article is to develop the mathematical model to describe response of endodontic file in curved root canal during the preparation of root canal using fracture mechanics approach. Any obturation process involves the filling of prepared root canal using bio-compatible materials like gutta-percha. During preparation of infected root canal, substrate, dead tissue and pulp is removed and tapered shape is formed so that any practitioner can fill it effectively. During preparation process of root canal, the canal wall applies locking action and causes resistance to motion of endodontic file, finally resulting into fatigue failure. This article described plastic behavior of endodontic file in curved root canal, mathematical model describing the necessary condition for crack growth in endodontic file, a mathematical model describing plastic zone size for crack on surface of endodontic file, a mathematical model describing crack tip opening displacement for crack on surface of endodontic file and mathematical model for pure-combined torsion and bending consideration for design of endodontic file. The mathematical model described is helpful for the Endodontic experts, researchers, design engineers. However the applicability of the described mathematical model limited to assumption of study. The gap between root canal to be prepared and endodontic file is zero while preparation. The endodontic file weight, speed of rotation and substrate removal rate is assumed to be constant. The mathematical model for endodontic file discussed above proved to be efficient tool for studying the root canal preparation.

Abstract: Cannulation of the aorta is done in order to provide oxygenation and circulatory function through the use of the heart lung machine during cardio-pulmonary bypass (CPB). The nature of the blood flow through the aorta and its ramifications during CPB is mostly linear as compared to the physiological flow, which is pulsatile in nature. This leads to the development of multiple morbidities caused by the development of emboli and atheromas. Perioperative postoperative care is necessitated by these conditions. As such the understanding of the blood flow characteristics is necessitated in order to effectively prevent the formation of emboli and to prevent the "Sandblasting" effect. The authors in this work seek to investigate the nature of blood flow through the aorta under such circumstances. The results obtained show the nature of blood flow in the cannulated aorta as well as the optimum angle of placement of the cannula with respect to the aortic wall.

Abstract: The main goal of this research work is to study and evaluate the muscles force and fatigue of Gastrocnemius Medialis (GMS), Gluteus Maximus (GM), and Gastrocnemius Lateralis (GL) during running for 400-meters based on surface Electromyography (sEMG) signals. The sEMG signals of the selected muscles from the right leg have been collected by using bipolar electrodes from 15 subjects during the run on the tartan athletic track with two pacing strategies. The first strategy: 1^st 200-meters running 87% - 94% of full speed and last 200-meters sprinting (full speed). The second strategy: 1^st 300-meters running 87% - 94% of sprinting and last 100-meters sprinting. The rate of fatigue has been calculated by using Root Mean Square (RMS) and Median Frequency (MDF) features. Then, the slopes of linear regression were calculated from both RMS and MDF at each 100-meters. The linear slope values represented the rate of fatigue and force. From the results of 1^st and 2^nd running strategies, the force of GM and GL muscles increased during the 4^th 100-meters of the 1^st strategy and decreased with GM and GMS muscles during the 4^th 100-meters of the 2^nd strategy. The less index fatigues were during the 1^st strategy for most selected muscles. Finally, it can be concluded the running with the 1^st strategy get less fatigues and the force of most selected muscles increased compared with the 2^nd strategy based on the results of time and frequency domain features (RMS and MDF).

Abstract: Despite the widespread use of reverse total shoulder arthroplasty, there is still a problem of conflict between the polyethylene cup of the prosthesis and the scapula, which over time causes the phenomenon of notching. In order to circumvent this problem correctly, several innovations have been proposed regard to the implementation method. In this context, the aim of this work is to study the biomechanical behavior of new implantation methods using different glenoid configurations in order to avoid the notching phenomenon between the cup and the scapula. The study was performed using virtual prototypes of the shoulder prosthesis assembly. Using CT scan images, three-dimensional models of shoulder bones were reconstructed. The implantation of the prosthesis in the three-dimensional model was performed in collaboration with an experienced surgeon from the Caduceus Clinic (Oran, Algeria). The numerical models were imported to finite element calculation software. After the validation of the numerical model using the literature results, we assessed the biomechanical behavior of four implantation methods under the same boundary conditions and abduction movements. From the obtained results, it was found that among the proposed methods, the BIO-SR lateralization method offers significant biomechanical advantages in terms of the forces applied to the glenoid during the abduction movement.

Abstract: Breast cancer is the utmost female tumor and the primary cause of deaths among female. Computer-Aided Detection (CAD) systems are widely used as a tool to detect and classify the abnormalities found in the mammographic images. A detection of breast tumor in a mammogram has been a challenge due to the different intensity distribution which leads to the misdiagnosis of breast cancer. This research proposes a dectection system that is capable to detect the presence of mass tumor from a mammogram image. A total of 160 mammogram images are acquired from Mammographic Image Analysis Society (MIAS) databse, which are 80 normal and 80 abnormal images. The mammogram images are rescaled to 300 x 300 resolution. The noise in the mammogram is suppressed by using a Wiener filter. The images are enhanced by using Power Law (Gamma) Transformation, ɣ = 2 for a better image quality. The greyscale information that contain tumor mass is extracted and used to model the proposed detection system by using 80% or 128 and of the total 160 mammogram images. The rest 20% or 32 mammogram images are used to test the performance of the proposed detection system. The experimental results show that performance of the proposed detection system has 90.93% accuracy.

Abstract: The paper deals with the application of specific methods of digital image analysis for the monitoring of morphological changes in cultures of filamentous microorganisms. First, a sequence of digital image preprocessing and processing steps is proposed for the treatment of microscopic images of a filamentous culture. The preprocessing step include band pass filtering by the Difference of Gaussians filter featuring a novel approach to the task of parameters tuning, as well as the optimization of image porosity and image objects separation quality. In the processing step, the resulting enhanced images are subject to morphological state characterization using a set of several standard and modified morphological parameters. Descriptions of morphological states of different complexity are then discussed varying from the standard set of mean values of parameters to the set of parameters in their full histogram of value frequencies (distribution) form. For such complex descriptions also new fashions of graphical representation of results without loss of information are compared. The potential of the proposed full description of morphological behavior of the culture is demonstrated using a set of microscopic images taken during an industrial antibiotics production cultivation using a microorganism belonging into the Streptomyces genus. Finally, the cluster analysis is proposed for further automatic quantitative classification and interpretation of complex description of metabolic states.

Abstract: A novel biocompatible fluorine substituted hydroxyapatite (F-HAp) / poly (ε-caprolactone) (PCL) bilayer coating on 316L SS with superior adhesion strength and admirable corrosion protection properties. PCL slurry was coated on 316L SS as a first layer using dip coating method followed by F-HAp coating as the second layer using electrodeposition method. The structural and functional group analysis of bilayer coatings were characterized by different analytical technique. Also, the mechanical properties of the bilayer coating showed higher adhesion strength than HAp and F-HAp coatings on 316L SS. The potentiodynamic polarization and electrochemical impedance spectroscopy results indicated that the admirable corrosion protection nature. The in vitro bioactivity test for coated 316L SS substrate was carried out by soaking it in the SBF solution, the induced apatite formation confirming the improved bioactivity of the specimen. Further, dissolution of metal ions was considerably reduced which was confirmed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The in vitro cell–material interaction of the bilayer coating was studied with human osteosarcoma MG63 cells for cell viability at 3, 7, 14 and 21 days of incubation and good biocompatibility was observed. The obtained results show that the F-HAp/PCL bilayer coating provides effective corrosion protection and enhanced bioactivity.

Abstract: Diamond like carbon (DLC) a carbon-based nanomaterial has been nominated as a potential solution to prevent the biofilm formation on indwelling medical devices such as dentures and heart valves. Candida albicans is an opportunistic fungal pathogen where biofilms are a part of its pathogenicity which primarily utilized indwelling medical devices as platform to build up the biofilm. In this work, DLC deposited on silicon substrate was prepared to accomplish the optimal characteristics for bio-coating material (roughness, purity, uniformity) and then evaluated for their ability to prevent or reduce the biofilm formation of pathogenic C.albicans (SC5314) under conditions mimicking human body. Optimized DLC was synthesized via chemical vapor deposition, and then the film was characterized by Raman spectroscopy, scan electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The potential biofilms on DLC, silicon substrate and positive control (polyvinyl chloride-PVC) were quantified via colorimetric cell viability assay (XTT); as intact and vortexed biofilms. The characteristics of formed biofilms were carried out using confocal scanning laser microscopy (CSLM) and scan electron microscope (SEM). The result showed that DLC was successfully deposited on the silicon substrate with a root mean square (RMS) roughness of 0.183± 0.09 nm. The biofilm efficaciously grown on all samples (DLC and positive control) with thickness of 46.8 ± 6.97 μm and 42.18 ± 4.65 μm, respectively. No topological and morphological changes have been observed by SEM on biofilm-DLC compared to PVC-biofilm. Moreover, all results indicated that the hydrophobicity and roughness of DLC appeared to support the attachment and the growth of C.albicans .In conclusion , there is no privilege of utilizing DLC over PVC in term of reduction or inhibition of C.albicans biofilm formation at physiological conditions. Furthermore, this study may serve as an experimental model to evaluate the potential effect of nanomaterials coating on biofilm formation at conditions mimicking human’s body.

Abstract: Hydrophilicity of apatite cement was increased after O₃ gas treatment on apatite cement (AC) powder. It results on the improvement of the handling and mechanical properties of set AC. Behavior of osteoblastic cells to O₃-treated set AC was evaluated including initial cell attachment, morphology of the attached cells and proliferation using rat bone marrow cell (RBM). Cells’ response to the set AC was the same regardless of O₃ treatment. The cells well attached and spread with filopodial extensions even over the O₃-treated set AC specimens. The rates of cell proliferation on set AC were also the same regardless of O₃ treatment. The result indicated O₃ treatment of AC powder would not affect to the osteoblast cell response of set AC.