Bio-Medical Materials and Engineering - Volume 17, issue 2

Authors: Mohd Janurudin, Juliana | Ozeki, Kazuhide | Aoki, Hideki | Fukui, Yasuhiro

Article Type: Research Article

Abstract: Hydroxyapatite (HA)/Hydrogen Peroxide (H2 O2 ) solutions was prepared for a tooth whitening application. HA powder was immersed in the 100, 1000 and 10 000 ppm of the H2 O2 solutions. The HA/H2 O2 , HA and H2 O2 solutions were applied to HA discs and extracted teeth for weight and whiteness change evaluation. After 24 hours, each HA disc was measured for the weight changes and each tooth was measured for the whitening changes (L* ) using a Spectro Color Meter. The topology of the teeth surfaces were also observed using Scanning Electron Microscope (SEM). The weight of …the HA disc applied with H2 O2 at all concentrations was lower than that applied with HA and HA/H2 O2 solutions. The whiteness of the teeth treated with HA/H2 O2 were higher than that treated with HA and H2 O2 only solutions. The whiteness change of the teeth treated with the HA/H2 O2 (10 000 ppm) showed the highest value in all solutions at L* =4.98±0.90 (p<0.05). In the SEM observation, the teeth surface treated with the H2 O2 showed rough and destructive holes on the enamel surface. However, the teeth surface treated with the HA/H2 O2 show smooth enamel surface due to covering of the destructive holes with HA powder. Show more

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 69-75, 2007

Authors: Maeda, Eijiro | Noguchi, Hitoshi | Tohyama, Harukazu | Yasuda, Kazunori | Hayashi, Kozaburo

Article Type: Research Article

Abstract: The central one-third portion of the patellar tendon (PT) is commonly used for the reconstruction of the anterior cruciate ligament. For better understanding of the healing mechanisms of the PT, tensile properties of collagen fascicles harvested from the healing PT were studied. A rectangular defect was made at the central third portion in each right PT in the skeletally mature rabbit. At 6 and 12 weeks, tensile tests were performed on fascicles from the tissue regenerated in the defect and the non-resected, residual tissue. The elastic modulus and tensile strength of fascicles from the regenerated tissue gradually increased in a …fashion similar to the bulk regenerated tissue. The properties of fascicles from the residual tissue were similar to those from normal tendons, which was very much different from those of the bulk residual tissue that were greatly deteriorated by the removal of the central portion. Show more

Keywords: Mechanical properties, patellar tendon, collagen fascicle, tissue healing, remodeling

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 77-85, 2007

Authors: Kobayashi, Koichi | Kakinoki, Toshihiko | Sakamoto, Makoto | Tanabe, Yuji

Article Type: Research Article

Abstract: The effects of strain rate and low-gamma irradiation on the compressive properties of ultra-high molecular-weight polyethylene (UHMWPE) were investigated. Gamma irradiation was performed at 30 kGy in nitrogen or at 29 kGy in air without post-irradiation treatment. Quasi-static and impact compressive tests using the split-Hopkinson pressure-bar technique were performed to measure stress–strain relations up to a true strain of 8% at strain rates of between 0.0004 and 260 s−1 . For both unirradiated and gamma-irradiated UHMWPE specimens, an increase in the strain rate significantly increased the Young's modulus and the 0.5% yield stress. Gamma irradiation in air significantly increased the …Young's modulus, as determined by quasi-static and impact compressive testing, and the 0.5% yield stress, as determined by impact compressive testing. The strain-rate dependence in the power-law relationship was similar to that observed for strain rates ranging from 0.02 to 0.10 s−1 (Kurtz et al., Biomaterials 23, 2002, pp. 3681–3697). Show more

Keywords: Gamma irradiation, impact compressive testing, strain rate, ultra-high molecular-weight polyethylene

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 87-95, 2007

Authors: Lewis, Gladius | Vejerla, Raghuveer | Mishra, Sanjay

Article Type: Research Article

Abstract: The objective of this study was to test the hypothesis that there is one model for the interface between the passive layer on the surface of an orthopaedic alloy and an electrolyte that has clinical relevance. To this end, electrochemical impedance spectroscopy measurements were made on mechanically-polished test specimens fabricated from three orthopaedic alloys [two Ti-based ones (Ti–6Al–4V and Ti–13Nb–13Zr) and a very-low-nickel austenitic stainless steel, Biodur® 108] while they were immersed in phosphate buffered saline (PBS) solution, at 37±1°C, over a period of 25 d. Through a statistical comparison between the experimental results (Nyquist and Bode plots) and …those computed using seven different equivalent electrical circuits (each representing a different model of the aforementioned interface), it was found that one circuit (comprising an arrangement of three resistances and three capacitances in series with a resistor representing the solution resistance) provided the best-fit in all three alloy surface-PBS solution systems, thus providing support for the working hypothesis. The variation of each of the circuit elements with time of immersion of the specimen in the PBS solution and the study limitation are discussed. Show more

Keywords: Ti–6Al–4V alloy, Ti–13Nb–13Zr alloy, Biodur$^{\textregistered}$ 108, electrochemical impedance spectroscopy

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 97-108, 2007

Authors: Yip, C.P. | Walker, D. | Fernlund, G. | Pinder, K.

Article Type: Research Article

Abstract: There are few studies on the effect of in situ fibroblast viability on the mechanical properties of skin. This study examines the effect of poison (2-deoxy-D-glucose) and strain on fibroblast viability and stress-relaxation in skin samples from the backs of 20 same-age male rats. Skin samples were either soaked in Kreb's solution or in poison and was then either strained or left unstrained, for a total of four different treatment groups. All samples were fixed and processed for apoptosis assay and light microscopy. The viability study showed that strained tissues soaked in Kreb's solution had significantly more apoptotic cells compared …to unstrained tissues soaked in the same solution. For tissues soaked and strained in poison the increase in apoptotic cells was negligible. Samples strained in Kreb's solution were found to have greater stress relaxation compared to samples strained in Kreb's solution with poison. The amount of stress relaxation was found to correlate with the number of viable fibroblasts in the tissues; tissues with more viable fibroblasts have lower stress relaxation. According to the relationships observed, fibroblasts do play an important role in the mechanical properties of rat skin tissues. Show more

Keywords: 2-deoxy-D-glucose, apoptosis, stress relaxation, strain, dermal fibroblasts

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 109-117, 2007

Authors: Farmanzad, Farhad | Najarian, Siamak | Eslamee, Mohammad Reza | Seddighi, Amir Saeed

Article Type: Research Article

Abstract: To obtain an appropriate model for the simulation of the biomechanical behavior of brain tissue and the deformation of ventricles, in particular, we have developed a novel computerized plain strain finite element model. For optimum results, a multiple loading solutions approach using various tissue parameters for the simulation of epidural hematoma have been tested. For this purpose, CT-Scan of a patient with traumatic epidural hematoma has been modeled. By changing the tissue parameters (E and ν) and increasing intraventricular pressure gradient, the displacement of similar points in the modeled ventricle was compared with the true values obtained from patient's CT-Scan …taken 3 months later after the resolution of hematoma. The magnitudes leading to least errors were determined. Best solutions were obtained with E=11–12 kPa and ΔP=1.25–1.5 kPa (7.5–9.4 mmHg), which were consistent with the patient's clinical condition. Biomechanical modeling of unilateral displacement loadings, which are the conditions similar to surgical navigation systems, without considering ventricular geometry and their internal pressure resulted in unacceptable results. Show more

Keywords: Brain tissue, biomechanical modeling, intraventricular pressure, epidural hematoma, finite element

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 119-125, 2007

Authors: Shimojo, Nagahiro | Kondo, Chihiro | Yamashita, Kyoko | Hoshino, Takeshi | Hayakawa, Taro

Article Type: Research Article

Abstract: A recently developed novel Ti–29Nb–13Ta–4.6Zr alloy (Ti–Ta) was investigated physically and chemically, and the results suggested it to be a possibly suitable dental material. In this study we analyzed the effects of the alloy, in comparison with those of other dental metals, on the adhesion, spreading, and proliferation of human gingival fibroblasts (Gin-1 cells) in vitro. The Gin-1 cells adhered and spread well on the Ti–Ta as well as on commercially pure titanium (Ti) and commercial Ti–6Al–7Nb alloy (Ti–Al), forming long processes showing a typical fibroblastic morphology that was close to that on glass. The proliferation of Gin-1 cells was …significantly suppressed on Au–Pd–Ag alloy (Au–Pd) and commercially pure copper (Cu); however, the cells proliferated as well on Ti–Ta as they did on Ti, Ti–Al, and glass. Though most of the Gin-1 cells on Cu and about half of them on Au–Pd died after 1 day and 5 days of culture, respectively, the cells on Ti–Ta, Ti, Ti–Al and glass showed 100% viability even after 5 days of culture. These results suggest that the newly developed Ti–Ta alloy has biocompatibility as good as that of Ti and Ti–Al with respect to morphology and proliferation of Gin-1 cells in vitro. Show more

Keywords: Ti–Nb–Ta–Zr alloy, Ti–Al–Nb alloy, Au–Pd–Ag alloy, biocompatibility, gingival fibroblasts, adhesion, spreading, proliferation

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 2, pp. 127-135, 2007