Bio-Medical Materials and Engineering - Volume 5, issue 2

Authors: Lee, Junhee | Aoki, Hideki

Article Type: Research Article

Abstract: Hydroxyapatite (HAP)-coated metal composites were made by the dipping method. The specimen substrates were Ti plates with a thickness of 2 mm. The HAP coating was carried out in HAP-sol for 1 min by the dipping method. The concentration of HAP-sol for the coating ranged from 3.28 to 9.99 wt%. Excellent coating was observed on Ti substrate dipped once in 9.99 wt% sol. A surface pretreated with a sandblasting provided a much better coating than a smooth surface. As the concentration of sol increased, the weight change and the coating thickness increased. Above 7 wt% sol, they increased sharply.

Keywords: hydroxyapatite, dipping method, thin coating

DOI: 10.3233/BME-1995-5201

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 49-58, 1995

Authors: Wan Abas, W.A.B.

Article Type: Research Article

Abstract: The response of human skin to “stress relaxation” tests at low loads in vitro was investigated. A number of behaviours, other than those already well established and documented, were observed. The significant behaviours are pure recovery and relaxation-recovery. Other behaviours observed are temporary stress recovery during the relaxation process, and momentary sudden non-linear drop in stress value followed by a second relaxation. The pure recovery and relaxation-recovery responses are repeatable. The latter represents the transitional response between the well-known behaviour of stress relaxation and the behaviour of stress recovery.

Keywords: skin in vitro, uniaxial loads, time dependency, stress relaxation, stress recovery

DOI: 10.3233/BME-1995-5202

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 59-63, 1995

Authors: Lewis, Gladius | Newman, John | Katz, William

Article Type: Research Article

Abstract: Two surface analytical spectroscopic techniques (namely, angular-dependent X-ray photoelectron spectroscopy and static secondary ion mass spectrometry) were used to characterize the nature and composition of the surface and near-surface layers formed on three biomedical polymers (namely, low-density polyethylene, expanded polytetrafluoroethylene, and a silicone elastomer) when exposed to Factor Xa in a buffer solution under adsorption conditions. It is shown that the results extracted from the spectroscopic measurements are consistent with each other. The clinical significance of the results is discussed in terms of screening biomedical polymers for use in fabricating cardiovascular system components.

Keywords: X-ray photoelectron spectroscopy, secondary ion mass spectrometry, polymers, Factor Xa

DOI: 10.3233/BME-1995-5203

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 65-82, 1995

Authors: Li, Tuantuan | Takikawa, Kazuya | Yoshizawa, Kazutake | Sakatsume, Makuto | Aoki, Hideki

Article Type: Research Article

Abstract: Hydroxyapatite-sol was prepared by dispersing hydroxyapatite microcrystals into saline. The hydroxyapatite microcrystals were synthesized by neutralization reaction of calcium hydroxide suspension and phosphoric acid solution. Sizes of the hydroxyapatite microcrystals were less than 0.1 μm, and the mean value was 0.05 μm. The 0.2 ml hydroxyapatite-sol with a concentration of 14.8 mg/ml was injected into medullary cavities of rat femurs. Both sintered hydroxyapatite powder suspension and saline as comparative materials were injected into the medullary cavities in the same way. Reaction of the hydroxyapatite-sol in the bone medullary cavities was investigated histologically using light and transmission electron microscopes. After …3 days, new bone formation was observed by injection of hydroxyapatite-sol, while no bone formation was observed by injection of sintered hydroxyapatite powder and saline. Osteoblasts were observed endocytosing the hydroxyapatite-sol in the medullary cavities of the rats. Macrophages and undifferentiated osteoblasts were found around the hydroxyapatite-sol aggregation by transmission electron microscope. After 5 days, amounts of new bone increased and matured, forming trabeculae. Many osteoblasts were observed in a line along the surface of the bone. On the other hand, 5 days after injection of sintered hydroxyapatite powder and saline no bone formation was observed while at 10 days after injection, some immature new bone formation started to be observed. New bone increased and matured at 15 days postoperatively. From these results, it was concluded that hydroxyapatite-sol only quickly promotes the formation of new bone in bone marrow and can be used as injection liquid of new biomaterials for bone formation. Show more

Keywords: hydroxyapatite-sol, bone marrow, bone formation

DOI: 10.3233/BME-1995-5204

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 83-92, 1995

Authors: Oshida, Yoshiki | Hashem, Azza | Elsalawy, Randa

Article Type: Research Article

Abstract: Four different types of dental composite resins were subjected to the water sorption environment in both dyed and undyed distilled water for 1 and 5 weeks at 37°C. Weight changes due to the water sorption, effects of water sorption on mechanical properties, and fractographic observations were conducted. It was found that (i) the water sorption was diffusion-controlled, (ii) both break stress and modulus of elasticity reduced by increasing the amount of absorbed water, and (iii) fractographic observations showed that fracture pattern of the wet/dry/wet lamellar structure was not straight line, rather S-shaped pattern, suggesting that (a) mechanical properties (particularly, the …modulus of elasticity) of the wet portion were not same as those in the dry portion, and (b) there could be an internal residual stress developed at/in the interfacial zone between the dry and wet portion. By one-layer removal from the wet/dry/wet lamellar structure composites, the residual stress was calculated from measuring the radius of the curvature. It was found that for all water-sorbed composite materials, tensile residual stresses were developed, which were from 30 to 40% of the break stresses for TPH, Charisma, and Durafil VS, and was 78% of the break stress for Z100 material. Show more

Keywords: dental composite resins, water sorption, mechanical properties, Reuss average modulus, interfacial residual stress

DOI: 10.3233/BME-1995-5205

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 93-115, 1995

Authors: Yokobori Jr., A. Toshimitsu | Kawaharada, Takashi | Sasaki, Shigeru | Watanabe, Soubei | Fang, Shou-Heng | Komatsu, Shuichi | Hayashi, Toshihiro

Article Type: Research Article

Abstract: Cases with loss of articular cartilage or lowering of articular lubricant performance are frequent among patients afflicted by various gonarthropathies or those fitted with prosthetic joints. The management of such cases has necessitated evaluation studies on the clinical efficacy of using high molecular weight hyaluronic acid as an artificial synovial fluid with a view to improving articular lubricant performance. The proper implementation of such evaluation studies on lubrication performance requires testing methods capable of assessing basic lubricant performance not ouly with respect to articular cartilage alone but also with respect to various other combinations of materials, i.e., lubrication between articular …bone and artificial joints, etc. In the present study, first, a simple standard lubricant performance test using several small readily procurable test specimens was devised. Then, this test was employed to evaluate the basic lubricant properties of hyaluronic acid intended for use as artificial synovial fluid. Show more

Keywords: mechanical testing, pendulum type friction tester, skeletal joint, hyaluronic acid, lubrication, molecular weight, viscosity

DOI: 10.3233/BME-1995-5206

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 117-124, 1995

Authors: Oshida, Yoshiki | Miyazaki, Masasi | Osman, Hisham | Xirouchaki, Loretta

Article Type: Research Article

Abstract: The ductility of thin films is normally evaluated by conducting the bulge testing. However, the accuracy of the conventional type of mechanical bulge ductility testing unit is poor in determining the actual elongation. In this development, a photo-sensitive device is provided in the detecting portion to accurately measure the elongation. The sensitivity depends on the type of the materials tested. A Pyrex® glass ball is utilized as a punching ball to provide equally distributed light. Pushing of the Pyrex glass is activated by a hydraulic media to control the punching velocity. Accuracy and reproducibility were primarily checked with copper thin …foil deposited on polyimide substrates. Two types of dental articulating papers (paper-based and plastic-based) were tested. It was suggested that an appropriate selection of articulating paper to mark the occlusal interferences is essential for precise determination of occlusal harmony. Show more

Keywords: ductility, bulge test, thin film, articulating paper, occlusal function

DOI: 10.3233/BME-1995-5207

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 2, pp. 125-139, 1995