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1
Content available remote Stiffness and strength of composite acrylic bone cements
EN
Purpose: Different acrylic bone cements based upon PMMA-MMA system are applicable for implant fixation in bone tissue. The aim of present study is the optimisation of the structure of some new bone acrylic cements made on the basis of PMMA-ethylmethacrylate-triethyleneglycoldimethacrylate and bone cements having additives (HA and radio pacifier), and the finding of the effect of these modifications on the flexural strength and stiffness. Design/methodology/approach: Different new bone cements on the basis of PMMA-EMA-TEGDMA system (ABC) were developed experimentally. The stiffness and strength of the samples of these modified cements were determined in the special three point bending equipment. Findings: A comparison of the flexural properties of new PMMA-EMA-TEGDMA cements and commercial available PMMA-MMA cement showed that commercial bone cement had larger values of ultimate strength of modulus of elasticity, but the difference is not very important. As concerns the polymerisation peak temperature, then there is a significant difference between commercial PMMA-MMA cement (-800C) and PMMA-EMA-TEGDMA modified cements (50-600C). The introduction of 10% and 18% of HA into solid phase does not influence essentially strength and modulus of elasticity of the PMMA-EMA-TEGDMA bone cements. The introduction of radio pacifier BaSO4 into bone cement leads to flexural strength diminishing. Low polimerisation peak temperature and appropriate mechanical properties of bone cements developed allows regarding new 3-D structure acrylic bone cements as promising biomaterials. Research limitations/implications: It is supposed to carry out animal testing to learn more about reaction of modified implanted material on the biological environment. Practical implications: The new materials could be efficiently used as bone cements because they will not damage surrounding biological tissue during curing. Originality/value: Paper is providing the new information about possibilities to realize the safe fixation of implants.
EN
A satisfactory finite element analysis model of the human mandibular and dentition system besides the detailed 3D geometry and static elastic properties should also consider time-dependent mechanical properties of different components of the jaw bone. Compact bone tissue plays the major role in this time dependence. The aim of the work was to investigate the active creep of the compact part of human mandibular bone. Creep tests of 15 specimens were conducted at room temperature, with applied constant compressive stresses between 5 and 40.8 MPa. The obtained results were approximated with exponential function. Average values of the creep properties of human jaw compact bone tissue for 5 specimens group were achieved.
EN
Two types of new composite implant materials are investigated. Their mechanical characteristics and biocompatibility are determined. The first type of the biomaterials is based on silicate glass (SG) and hydroxyapatite. Both the natural (NHAp) and a synthetic (HAp) hydroxyapatites were used. The second type of the biomaterials was made of an ultrahigh-molecular polyethylene (UHMPE) and the NHAp. Composite materials of both the types were implanted into the rabbit femur. The bond strength between the bone tissue and the implants was determined in 2, 4, 10, and 25 weeks. The stress–strain state of bone–implant system was determined by the finite element method (FEM).
4
Content available remote General principles of bone tissue testing
EN
Five basic principles that govern the structure and biomechanical behaviour of biological tissue have been analysed. Many different factors of the mechanical and biological origin, which can significantly affect the mechanical properties and, consequently, the mechanical behaviour of the bone tissue are presented and discussed. The effect of structural levels in the bone tissue on the selection of proper size of the test specimens is emphasised. Different aspects of the testing procedure of bone tissue are discussed. Peculiarities of the distribution of its biomechanical properties in the man left tibia are described.
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