Bio-Medical Materials and Engineering - Volume 3, issue 4

Authors: Yokobori, Jr., A. Toshimitsu | Ohkuma, Tsuneo | Yoshinari, Hiromi | Ichiki, Masataka | Ohuchi, Hirosi | Yokobori, Takeo

Article Type: Research Article

Abstract: A mechanical test on small caliber blood vessel is difficult because the strength is very low and the dimension is very small. In the present paper a multifunctional axial test apparatus design is proposed. This has the characteristics such that the load cell and the environmental container for the specimen are built up in terms of cassette, respectively, and thus both are easy to equip and take off, that is, easy to replace. Also, the test methodology by internal pressure for small caliber blood vessels has been proposed. By using both of these methodologies, the characteristics of the mechanical behavior …of small caliber blood vessels, such as compliance, stress relaxation, and viscoelastic property have been clarified. An attempt has been made on the application of this method to a clinical case. Show more

Keywords: multifunctional axial test, test methodology by internal pressure, small caliber blood vessel, compliance, stress relaxation, viscoelastic property

DOI: 10.3233/BME-1993-3401

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 175-183, 1993

Authors: Oshida, Yoshiki | Hashem, Azza

Article Type: Research Article

Abstract: The bonding strength of porcelains to metals depends on the oxide layer between the porcelain and the metal. Oxidation of a metal surface increases the bonding strength, whereas excessive oxidation decreases it. Titanium and its alloys are gaining acceptance for dental use since they exhibit excellent biocompatibility, corrosion resistance, low specific gravity, good mechanical properties, and low cost. However, titanium suffers from its violent reactivity with oxygen at high temperatures that yields an excessive thick layer of TiO2 , and this presents difficulties with porcelain bonding. The present study deals with the oxidation kinetics of titanium simulated to porcelain firing …and evaluating surface nitridation of titanium as a process of controlling the oxidation behavior of titanium. Nitrided samples with the Arc Ion Plating PVD process and un-nitrided control commercially pure titanium (CPT, Grade 1) were subjected to oxidation simulating firing of Procera porcelain with 550°, 700°, and 800°C firing temperatures for 10 min in both 1 and 0.1 atmospheric air. Weight difference before and after oxidation was calculated and the parabolic rate constant, Kp (mg2 /cm4 /s), was plotted against inverse absolute temperature. Surface layers of the samples were subjected to x-ray and electron diffraction techniques for phase identifications. Results revealed that both nitrided and un-nitrided samples obey a parabolic rate law with activation energy of 50 kcal/mol. In addition this study shows that nitrided CPT had a Kp about 5 times lower than the un-nitrided CPT and hence the former needs about 2.24 times longer oxidation time to show the same degree of oxidation. Phase identification resulted in confirming the presence of TiO2 as the oxide film in both groups but with 1 – 2 μm thickness for the un-nitrided CPT and 0.3 – 0.5 μm thickness for the nitrided samples. Therefore it can be concluded that nitridation of titanium surface can be effective in controlling the surface oxide thickness that might ensure satisfactory bonding with porcelain. Show more

Keywords: pure titanium, metal ceramic system, nitrided titanium, oxidation, x-ray, transmission electron diffraction

DOI: 10.3233/BME-1993-3402

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 185-198, 1993

Authors: Murakami, Kenkichi

Article Type: Research Article

Abstract: The structural changes of material caused by chemical reaction are reflected in the viscoelastic properties of these substances. Such a viscoelastic property induced by chemical reaction was termed chemorheology. Therefore, chemorheology is a relatively new discipline encompassing the physical and chemical aspects involved in the elucidation of the mechanisms, at a molecular level, of structural changes of polymers during their degradation. The studies presented here are the results stimulated further research in areas where this new determination will be more developed.

DOI: 10.3233/BME-1993-3403

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 199-209, 1993

Authors: Yahia, L. H. | Drouin, G. | Zukor, D.

Article Type: Research Article

Abstract: In this study, the effect of sterilization was investigated on the mechanical properties of rabbit's meniscal grafts. The processes of freezing and irradiation were carried out and their effects upon the elastic and viscoelastic properties measured using a tensile testing machine and an indentation test. It was found that gamma irradiation, at dosages commonly used for sterilizing grafts, had a significant adverse influence on the elastic and viscous response of the grafts. Freezing led also to a small significant decrease in elastic stiffness but no change in failure strength. It is concluded that irradiation sterilization is unsuitable for clinical use …and other techniques should be used whenever possible. Show more

Keywords: meniscal grafts, irradiation, sterilization, mechanical properties

DOI: 10.3233/BME-1993-3404

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 211-221, 1993

Authors: Lu, Luo | Jones, Michael W. | Wu, Richard L. C.

Article Type: Research Article

Abstract: Ion beam assisted diamond-like carbon (DLC) films have been used for growing the human hematopoietic myeloblastic ML-1 cells and human embryo kidney 293 cells in the control environment. DLC films were directly deposited onto the P-35 plastic dishes by impacting the high kinetic energy (1000 eV) of methane ions at room temperature. The present results showed that both ML-1 and HEK 293 cells continuously grow with and without DLC films. It has demonstrated that human cells proliferated on DLC film with very high viability and DLC material had no toxicity to cultured human ML-1 and HEK 293 cells. We conclude …that DLC film is a biological compatible material for potential cell culture matrix and bio-medical applications. Show more

Keywords: diamond-like carbon, bio-materials, biocompatibility, human cell culture

DOI: 10.3233/BME-1993-3405

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 223-228, 1993

Authors: Otsuka, Makoto | Matsuda, Yoshihisa | Kokubo, Tadashi | Yoshihara, Satoru | Nakamura, Takashi | Yamamuro, Takao

Article Type: Research Article

Abstract: A novel device consisting of Eudragit-coated cephalexin as a model drug and a self-setting bioactive cement based upon CaO-SiO2 -P2 O5 glass was investigated. The glass cement hardened within 5 min of mixing with a phosphate buffer. After setting, in vitro drug release from homogeneous or heterogeneous drug-loaded cement pellets in a simulated body fluid (SBF) at pH 7.25 and 37deg;C continued for over 2 weeks. The hardened cement gradually formed low-crystallinity hydroxyapatite and decreased in volume by about 5% during drug release in SBF. Consequently, 30% of the loaded drug was initially released from the homogeneous cement system, …and thereafter it was released more slowly. Since the heterogeneous system consisting of the cement and a 50% polymer coated, drug-loaded pellet avoided this drug's burst, the drug was released over a longer period than that in the homogeneous system. The heterogeneous system released the polymer-coated drug very slowly, because it completely avoided the initial burst, and sustained the release over a long period. Show more

Keywords: hydroxyapatite, bioactive material for artificial bone or teeth, self-setting bone cement, bioactive bone glass cement, drug delivery system for skeletal tissue, drug release test

DOI: 10.3233/BME-1993-3406

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 229-236, 1993

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 3, no. 4, pp. 237-244, 1993