Bio-Medical Materials and Engineering - Volume 16, issue 3

Authors: Aoki, H. | Ozeki, K. | Ohtani, Y. | Fukui, Y. | Asaoka, T.

Article Type: Research Article

Abstract: Three-dimensional finite element analysis was performed for thin hydroxyapatite (HA) coated and titanium dental implants to study the effects on stress/strain distribution in the mandible with application of axial and oblique loads. The implants were of screw and cylinder types. With an axial load, the maximum equivalent bone stresses in the titanium implants were 21.5 and 29.0 MPa for the cylinder and screw types respectively, and the stress and strain distributions differed. For the cylinder type, the highest stress was located at the implant base, and for the screw type, it was located at the top edge of the first …thread within the cortical bone. For the HA-coated cylinder and screw implants, the maximum equivalent bone stresses were 7.1 and 7.2 MPa respectively. The stress and strain distributions were similar, and the highest stress was located on the upper side of the cortical bone around the implant neck for both implants. Of the implants examined, the screw type HA-coated implant had the most uniform stress distribution in bone. Show more

Keywords: Dental implant, finite element analysis, hydroxyapatite

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 157-169, 2006

Authors: Martin, Edith | Manceur, Aziza | Polizu, Stéfania | Savadogo, Oumarou | Wu, Ming H. | Yahia, L'Hocine

Article Type: Research Article

Abstract: The beta-titanium alloy, a particular type of titanium, has been investigated as a biomaterial because of its good mechanical performances and its high corrosion resistance and biocompatibility. This work focuses on the corrosion performance of a β-titanium alloy of composition Ti–11Mo–2V–4Nb–3Al in Hank's physiological solution. Potentiodynamic tests were performed from −0.25 V to 3.5 V; the breakdown potential was not reached. To observe the behaviour of the alloy while submitted to long-term aggressive conditions, 1, 4 and 8 cycles of cyclic polarization were carried out. Results show a high resistance of the alloy to corrosion and a stabilization of the …surface after several corrosion cycles. Pitting was not observed and a fast ability of the surface to repassivate was noticed. The surface was characterized by different techniques before and after corrosion testing. Following the corrosion tests, X-ray Photoelectron Spectroscopy (XPS) showed the presence of calcium and phosphorus, an increase of the oxide layer was measured by Auger Electron Spectroscopy (AES), a relatively smooth surface was visualised by Scanning Electron Microscopy (SEM) and contact-angle measurements showed that the surface energy increased. Show more

Keywords: Beta-titanium, corrosion, cyclic polarization, surface characterization, biocompatibility

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 171-182, 2006

Authors: Leung, Ting-Kai | Chang, Chih-Pong | Lee, Chi-Ming | Shen, Li-Kuo

Article Type: Research Article

Abstract: A retrospective study of patients' records on reviewing the purpose of venous catheter insertion (chemotherapy, blood transfusion, antibiotics or parenteral nutrition); total period of insertion; reason for catheter removal. 120 admitted patients who received fluoroscopic guide PICC (4-French single lumen silicone rubber catheter) insertions into distal SVC via antecubital region of forearm. We retrospectively review human factors including the patients' laboratory data of pre- and post-insertion, total insertion period and reasons for withdrawal. The important human factors that affect the clinical outcome of PICC were also evaluated. The results indicated that the most common complications were wound oozing, phlebitis, occlusion, …infection and leaking. Persistent wound oozing for over 3-day-period is the higher incidence of complication. It also demonstrated a surprisingly high ratio (>77%) in those patients with thrombocytopenia and leukemia. In this group, persistent low platelet counts could be noted, the ratio of failure (remove PICC within 3 days) is 10% and there is 40% decrease insertion period (<30 days). Prospectively, it is worthwhile to choose new material or new technology of surface coating of PICC, to decrease consumption of platelet thrombogenic proteins and to maintain normal coagulate function of human bodies. Show more

Keywords: PICC insertion, thrombocytopenia, anti-thrombogenic, clinical, silicone-rubber, biomaterials, intravenous cannulation, polyurethane, surface coating

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 183-188, 2006

Authors: Qiao, Aike | Liu, Youjun

Article Type: Research Article

Abstract: The graft–host diameter ratios have impacts on the flow patterns of bypass graft. In order to clarify the influence of graft–host diameter ratios on the flow patterns and the wall shear stress in coronary artery bypass graft (CABG), the pulsatile blood flows in three CABG models, with the graft diameter larger than, equal to and smaller than that of the coronary artery, were simulated with finite element method. The temporal-spatial distributions of flow patterns, wall shear stresses (WSS), wall shear stress gradients (WSSG), oscillating shear index and shear stress ratio were depicted and compared. Of the three models evaluated, large …model can bring about better hemodynamics to some extent with relatively large positive longitudinal velocity, uniform and large WSS, and small WSSG. The results suggest that larger or isodiametric graft is favorable. However, no distinct difference of WSS based temporal parameters was found between all the three models. Alternative anastomotic designs are necessary for the improvement of CABG patency rates. Show more

Keywords: Diameter, bypass graft, geometry configuration, intimal hyperplasia, numerical simulation, hemodynamics

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 189-201, 2006

Authors: Chu, C.L. | Xue, X.Y. | Zhu, J.C. | Yin, Z.D.

Article Type: Research Article

Abstract: Biocompatibility and bonding strength of hydroxyapatite–20vol%Ti composite fabricated by hot-pressing technique with bone tissues in the rabbit were investigated by in vivo studies in comparison with those of Ti metal and dense HA ceramic. Although fibrous tissues formed at the interface between the composite and bone tissues at 3 weeks in vivo, bonding strength of the composite increases faster than that of dense HA after 4 weeks. At 3 months in vivo, bonding strength of the composite is higher than that of dense HA and exceeds 6.5 MPa. Moreover, as compared with the visible bonding interfaces between dense HA and …new bones, the bonding interfaces for the composite cannot already be distinguished and the composite was osseointegrated fully with bone tissues into one bony body. The shear fracture of bonding strength test for the composite occurred in new bone zones near the interface, which indicates that bonding strength of the composite could even exceed the shear strength of new bones after 3 months in vivo. In conclusion, HA–Ti composite has better osteoconduction and osseointegration abilities than Ti metal and dense HA ceramic after 3 months in vivo and is a promising biomaterial for hard tissue replacement. Show more

Keywords: Hydroxyapatite composite, titanium, biocompatibility, osseointegration

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 203-213, 2006

Authors: Du, Chunjuan | Ma, Hongshun | Ruo, Min | Zhang, Zhongjun | Yu, Xiaojun | Zeng, Yanjun

Article Type: Research Article

Abstract: Objectives: To study the comprehensive biomechanical properties of the cancellous bone of distal femur through a series of mechanical tests, and provide relevant subjects with the basic technical data. Backgrounds: The study on bone mechanics is a commonly used approach to evaluate the biomechanical competency of bone. The biomechanical properties of bone have come to be the precondition of the further research of these relevant clinical subjects. Methods: In this paper, comprehensive items of mechanical properties of the cancellous bones of distal femur were conducted, and many valuable test results were obtained through a series of mechanical tests, which comprised …tensile test, compression test, torsion test, shear test, bending test and impact test. The specimens were extracted from the normal corpses of Chinese donors died from acute head injury. As another key problem in this kind of experiment, the sampling and fixing method of cancellous bones specimens was developed and optimized in this research. Results: A series of the experimental data of mechanical properties of cancellous bones were obtained in the tests, these experimental data include tensile strength, compression strength, yield tensile strength, modulus of elasticity, torsion strength, shear strength, torsion modulus, bending strength, yield shear limit and impact toughness, which can reflect the complex mechanical competency of bone, being of great value and practice in clinic and further research on cancellous bones. The mechanical properties of the cancellous bones of distal femur were analyzed and discussed. Conclusions: The biomechanical properties of the cancellous bones have a close relationship with individual difference. Comprehensive items of the mechanical properties of the bone can evaluate the mechanical performance of the bone better, and can provide more valuable data to relevant research. Show more

Keywords: Mechanical properties, cancellous bones, distal femur, biomechanics

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 215-222, 2006

Authors: Chowdhury, M.N.K. | Alam, A.K.M.M. | Dafader, N.C. | Haque, M.E. | Akhtar, F. | Ahmed, M.U. | Rashid, H. | Begum, R.

Article Type: Research Article

Abstract: Poly(vinyl alcohol) (PVA) can be modified to polymer hydrogels by radiation crosslinking and can be used in different biomedical applications. A study was done on the optimization of ingredients concentration for preparing good quality PVA hydrogels with natural polysaccharides. The synthesized hydrogels were also characterized by measuring the different physical properties e.g. gel fraction, swelling and absorption rate. Besides these, sterility test were also performed. Good quality hydrogels were obtained from PVA and natural polysaccharides solutions with 27 kGy radiation dose. There is an influence of natural polysaccharides on the gel fraction of hydrogel. The increase in the amount of …polysaccharide causes a decrease in gel fraction that is decrease in the crosslinking density of PVA hydrogel network. The prepared hydrogels were found to be sterile. Show more

Keywords: Hydrogel, biomaterials, polysaccharide, crosslinking, grafting, radiation dose, gel fraction, swelling ratio, absorption rate, sterile

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 3, pp. 223-228, 2006