Papers by Keyword: Bone Remodeling

Abstract: The aim of this study is to investigate the effect of soaking time on the compositional and morphological changes of dicalcium phosphate dihydrate (DCPD)-coated β-tricalcium phosphate (β-TCP) bioceramic. In this study, an established method from our research group was used to prepare the β-TCP bioceramic pellets and expose them to acidic calcium phosphate solution for 2, 4, 6, and 8 hours to obtain DCPD coated layer on β-TCP pellets through dissolution-precipitation reaction. Characterization methods such as x-ray diffraction analysis (XRD) and scanning electron microscope (SEM) were carried out on the specimen. XRD and SEM analyses indicated that the peak intensity and density of DCPD crystal precipitated on the pellets were increased when increasing the soaking time. Therefore, it was confirmed that the DCPD coated layer formation on the β-TCP pellet surfaces depended on the exposure time to acidic calcium phosphate solution.

Abstract: The aim of this study is to investigate the behavior of osteoclast cells response on dicalcium phosphate dihydrate (DCPD) layer-coated β-TCP granules. β-TCP granules with 300-600 μm were exposed to acidic calcium phosphate solution for 30 mins in order to get 10 mol% DCPD layer-coated β-TCP granular. DCPD free-coated β-TCP granular had used as control specimen. Both specimens were implant in 9 mm of rat calvarial bone defect for 4 weeks. After 4 weeks, the block section of rat calvarial containing specimen were removed for Tatrate-Resistance Acid Phosphatase (TRAP) analysis. Results of TRAP staining reveal that the number of osteoclast cells attached on 10 mol% layer-coated β-TCP granular is higher than DCPD free-coated β-TCP granular. Since remodeling of new bone formation involved simultaneous osteoclast and osteoblast cells response, therefore, the results obtained in this study indicated that the presence of DCPD layer-coated on β-TCP granular helps to improve osteoclast cells response that contribute in stimulating new bone formation.

Abstract: It is widely accepted that bones have the ability to adapt to new biomechanical environment by changing their material properties, geometry and inner architecture. Bones have also an exceptional ability to self-repair, to remove microcracks and to prevent the bone damage caused by the fatigue failure. These abilities are enabled through coupled processes of bone resorption and bone formation, the processes collectively referred to as bone remodeling. Numerous studies have shown that bone remodeling is governed by combination of mechanical stimulus (strains) and its frequency, both sensed by sensor cells (osteocytes). Through mechanotransduction, the stimulus is transmitted to actor cells (osteoclasts, osteoblasts) that actually do the bone resorption or formation. Several theories have been proposed to predict bone remodeling and several finite-element-based algorithms have been introduced. The vast majority of them uses strain energy density as the mechanical stimulus. The purpose of this paper is to investigate and discuss the applicability of also other strain-based representations of the mechanical stimulus in simulations of remodeling of bone with an initial microcrack. The need for developing more reliable models is essential for both clinicians and engineers who are interested, for instance, in prediction of bone performance when various implants are involved.

Abstract: This study aimed to evaluate the biomechanical responses in the peri-implant bony structure installed with the fixed partial dentures (FPDs). Unlike traditional configuration, the FPD considered here comprises a superstructure and is supported by three implants. The computational model of mandibular bone and the implant prosthesis were constructed based on patient-specific computerized tomography (CT) images and Computer Aided Design (CAD) tools. To better reflect the real clinical situation, the 3D real-time loading data of maximum voluntary clenching measured using piezo-electric force transducers in patient were adopted in the 3D finite element (FE) analyses (FEA). The von Mises equivalent stress, maximum shear stress, equivalent strain and strain energy density in the peri-implant bone regions are quantified. The peak stresses and strains in the peri-implant bone were observed around the neck of the implant, indicating risk of micro-motion and bone resorption. In this study, we successfully conducted a computational simulation in silico based on in vivo 3D force measurement of a specific patient. The results provided important biomechanical data for clinical treatment, potentially helping enhancing the longevity and reliability of the implant-supported FPD restoration.

Abstract: The mathematical theories of bone mechanical adaptation are based on a nonlinear ordinary differential equation which governs the evolution of bone density with respect to the applied loads. If the density distribution achieved within a certain bone model resembles the expected distribution observed in the real bone, then the mathematical theory is usually thought to be suited for such simulations. As test problem, it was extensively used the coronal section of the proximal femur. This section inspired the very creation of the mathematical models following Wolff’s observations regarding trabecular architecture. However, the lack of quantitative data when using the bi dimensional femur model prevents the quantitative validation of the adaptation mathematical models. Using computed tomography is now possible to reconstruct the three dimensional geometry of bones and also to estimate the apparent density based on correlations with the Hounsfield units. This method was already used to quantitatively validate the simulation of bone remodeling into different bones and proved to be efficient. The paper presents the apparent density distributions achieved into the 3D model of the proximal femur by coupling the finite element method with the Stanford bone adaptation equation. The densities obtained in this manner are compared by those determined from the tomographic data of the same bone. The purpose relies on establishing whether the three dimensional end proximity of the femur bone can be used for quantitative validation of remodeling simulations.

Abstract: The adaptation of bones to mechanical loads or bone remodeling can be simulated using specific mathematical models in conjunction with the finite element method. There are several theories proposed within the literature for the prediction of the bone behavior under mechanical loads and all have been used successfully, within certain limits of prediction details, but no unanimous acceptance have been reported yet. Within this context, it is important to know the differences and similarities between the results which these theories can produce, in order to improve their interpretation. On the basics of the above observation, the paper presents the comparison between density distributions achieved using three different models of bone remodeling: the original strain energy density equation developed at the University of Nijmegen, the principle of cellular accommodation incorporated into the Nijmegen model and the variant developed at the University of Manchester obtained by adding the quadric term which eliminates the density accumulation at physiologically unrealistic high loads. It is shown, using a suggestive test problem, that the three models generate significantly different results.

Abstract: The law of bone remodeling asserts that the internal trabecular bone adapts to external loadings, reorienting with the principal stress trajectories to maximize mechanical efficiency creating a naturally optimum structure. In this paper a new heuristic topology optimization method based on ordinary differential equations describing bone remodeling process is presented. The basis for numerical algorithm formulation was the phenomenon of bone adaptation to mechanical stimulation. The resulting optimization system allows fulling mechanical theorem for the stiffest design by use of presented heuristic topology optimization approach. Two widely used numerical examples are shown to confirm the validity and utility of the proposed topology optimization method.

Abstract: In this paper firstly a new hypothetical model of bone remodeling based on bone bioactivity mechanism and Turing reaction-diffusion equations is presented. Secondly this model of bone remodeling is translated to material formation and resorption process of continuum structures, a new heuristic structural topology optimization is presented. Finally short cantilever beam problem, one of the widely used examples in structural topology optimization are carried out by using present method to confirm the validity of the proposed topology optimization method.

Abstract: Inorganic component of bone is not hydroxyapatite but carbonate apatite. Although pure carbonate apatite (CO₃Ap) has not been prepared due to the limited thermal stability of CO₃Ap, dissolution - precipitation method using precursor block allows fabrication of pure CO₃Ap. Fabrication of CO₃Ap, cell response, tissue response and improvement of CO₃Ap will be discussed.

Abstract: A new damage-adaptive bone remodeling model, in which an algorithm incorporating both strain and damage stimuli, is developed in this paper. Typically, a human proximal femur model is established to predict the bone mass distribution during bone remodeling process. And human physiology damage-repair cycle is considered in the model. The governing equations of the mathematical model, digesting the predecessors’ ideas, are numerically solved and implemented into ANSYS software via the user interface of finite element algorithm. With the aid of this novel model, the whole healing behavior of human proximal femur is elucidated properly.