Papers by Keyword: Cancellous Bone

Abstract: The purpose of this study was to develop a new three-dimensional model of an osseointegrated molar dental prosthesis and to carry out finite element analysis to evaluate stress distributions and intensities in the bone and in the components of dental prosthesis under three loads (corono-apical, distal-mesial and buccal-lingual) were applied to the top of the occlusal face of the prosthesis crown. The interfacial stresses were also determined inside and outside of the threading when the dental prosthesis system was subjected to one of three masticatory loads. All materials used in the models were considered to be isotropic, homogeneous and linearly elastic. The elastic properties, loads and constraints used in the model were taken from published data. In this study, the stress concentration occurred around the threaded dental implant neck. Thus, this area should be preserved clinically in order to maintain the bone–implant interface structurally and functionally.

Abstract: Using porous bioceramics became recently an alternative approach to increase bone density which is a key factor for successful dental implant application. These novel biomaterials should substitute missing natural trabecular structures in terms of material strength as well as deformation characteristics. However, mechanical behavior of these materials used as bone fillers are still in question. This problem is made more difficult by the fact that bone structure itself exhibits a complex mechanical behavior which is still in question as well and, therefore, appropriate analytical criteria should to be established. The purpose of this paper is to determine typical mechanical behavior of trabecular structure of mandibular cancellous bone using computational simulations which can serve as a basis for establishing such criteria. For this purpose, four bone specimens of various bone density were μCT-scanned and high-level finite element models including detailed trabecular structure were created on their basis to analyze relevant mechanical quantities for various loadings in terms of bone density and various histomorphometric parameters.

Abstract: This work presents an experimental program to determine the mechanical properties of cancellous bone in the femoral head as a function of location. To achieve this several specimens of cancellous bone of approximately 10 mm height and 10 mm diameter were obtained from one human femoral head, starting the sampling from its main loading compressive direction. All specimens underwent compression testing in order to determine the mechanical properties of each specimen and thus a properties map of the cancellous bone in the femoral head was obtained. Based on the results a parametric file with material properties was created in order to be used by professionals in finite element analysis programs.

Abstract: Coral and converted coralline hydroxyapatites have been widely used in biomedical application as orbital implant and bone graft substitute. The aim of this study was to characterize the physical and chemical properties of various corals found in Bidong Island and determines their potential for development of bone graft substitute. Five species of coral which is commonly found in Bidong Island, Terengganu was collected and identified. The physical properties of corals such as density and porosity were determined using the Archimedes Principle, whereas a mechanical strength was determined using a universal testing machine. The structure of corals such as pore sizes and shape, distribution and pore connectivity was observed using Scanning Electron Microscope (SEM). Chemical properties of corals were characterized using X-ray diffraction (XRD), and energy dispersive x-ray (SEM-EDX). Five species of coral were identified as Leptoria, Porites, Platygyra, Acropora and Pocillopora. The densities of corals range from 2.00 to 19.00 g/cm³ while the porosity range from 15 to 60%. The corals structure consists of interconnected open pores with mean pore sizes in range of 100 to 600μm. Their compressive strengths are in the range of 4.92 to 27 MPa, which is higher than the reported strength for cancellous bone. SEM-EDX analysis shows the elements calcium carbonate (C, O and Ca) found in Platygyra. This result was supported by XRD analysis, which shows the calcium carbonate phase in form of aragonite presence in Platygyra. Aragonite phase was suitable for transforming coral to hydroxyapatite via hydrothermal treatment. Based on this finding, coral species in Bidong Island, Terengganu has been great potential to be used as bone graft substitutes.

Abstract: Morphology of cancellous bone has been studied for years, with researchers always seeking accurate methods to assess the parameters. They also study the importance of cancellous morphology in itself. Despite the amount of previous research, there are currently no reviews on the morphology at different anatomy. This paper evaluate the methods and parameters of cancellous bone morphology at different human anatomy. From 1997 to February 2014 we found the articles published on cancellous bone morphology vary in parameters at different anatomy of human bone. Further, researchers are also interested in finding the precision methods for identifying the parameters of cancellous bone. Both in vitro and in vivo were used in finding the accurate result of cancellous bone parameters whilst also searching the importance of the morphology parameters. The morphology studies are vital due to the direct relation with the mechanical properties of cancellous bone. Based on the morphology data, it is found that the morphology parameters are dissimilar at different human anatomy sites. A variety of methods were used by researchers in identifying the morphology parameters, with each method having its own advantages and disadvantages. This review paper summarises the pros and cons of all methods available, in order to help researchers select the best methods for their future studies.

Abstract: The permeability of the blood in the artificial cancellous are affected by certain morphological aspects that include pore diameter, pore size, porosity and the bone surface area. In this study, computational fluid dynamics method is used to study the fluid flow through the cancellous structure. Result of the present work show that geometries with the same porosity and overall volume can have different permeability due to the differences in bone surface area. The hexahedron geometry has the highest permeability under stimulated blood flow conditions, where the cylindrical geometry has the lowest. Linear relationship is found between permeability and the two physical properties, bone surface area and the pore size.

Abstract: During daily activities, trabecular bone need to bear certain amount of load which also leads to movement of the bone marrow within the structure. The flow of the bone marrow within the trabecular bone structure cause the shear stress which affect the nutrient transport, the properties of the bone and also the bone fatigue life. The aim of this paper is to simulate the trabecular structure using FSI approach in order to study the effect of the fluid flow to the structure. In this study, idealized model with 50% of porosity was used in the simulation and 1mm displacement applied on top of the model. Three different types of analysis were used in order to differentiate between CFD, CSM and FSI results. The results showed significant value between these analyses was concluded that FSI approaches is the best to mimic the real body condition.

Abstract: To investigate the effects of bony structure simplification methods on the biomechanics of tibiofemoral joint under compression and torsion effects in series of flexion angles, the MRI images of the normal human knee at flexion angles of 0°/25°/60°/80° were developed through SONATA MAESTRO 1.5T, then through the technology of threshold segmentation and registration assembly, bone tissue distinguished models and single material models were built based on these images. The results show that: (1) at the flexion angles of 0°/60°/80°, the maximum equivalent stress on femur and femoral cartilage significantly were slightly higher than single material models, only at 25 °, the maximum equivalent stress of the femoral cartilage in single material model was obviously larger; (2) difference of maximum equivalent stress on tibia and tibial cartilage between two kinds of models was not significant, and stress increased with the increase of flexion angle, only at 80 °, the stress on tibia of bone tissue distinguished models reduced; (3) The skeletal load was borne mainly by the cortical bone.

Abstract: To study whether the architectural parameters are sensitive to the shape of volume of interests in micro-CT scanning, six human C5 body samples were scanned by micro-CT. Cubic and cylindrical volumes of interests were acquired as the length of cubic samples was being changed continually. The nonlinear curve fitting method was employed to explore the correlation between the parameters and the volume of interests. The selected morphological indices showed a significantly variable tendency for the lengths of cubic and cylindrical regions of interests, except the Tb.Th and BS/BV. The Dunnett-t tests were performed to compare the architectural parameters of different region of interests against that of control group. There was no significant difference observed between the architectural parameters from cubic region of interests and that from the cylindrical region of interests.

Abstract: To establish clinical bone assessment for osteoporosis, it is necessary to evaluate not only bone density but also trabecular bone microstructure and mechanical properties of bone. Therefore relationship between the micro-structural parameters and the mechanical properties of the cancellous bone of bovine distal femur was investigated. Compression test was carried out using universal testing machine to measure Young’s modulus and the ultimate strength. X-ray CT was used to obtain 3D image of specimens. Bone trabecular orientation was obtained from fabric ellipse by the MIL (Mean Intercept Length) analysis. Young’s modulus and ultimate strength had a high correlation with bone density respectively; furthermore ultimate strength had a high correlation with Young’s modulus.