• Biomaterials and Biomechanics in Bioengineering
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• v.5 no.1
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• pp.1-10
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• 2020

This paper investigated vibrational behavior of the osteon as bone unit in the different situations. This study can lead to increase our knowledge of our body. In this paper free vibration of the osteon with considering it as composite material has been studied. The effect of numbers of lamellae and radius of those on natural frequency of osteon are subtle; while thickness of lamellae have decreasing trend on natural frequency of osteon. The presence of nerve and blood in haversian canal change trend of natural frequency, absolutely. Using the nonlocal strain gradient theory(NSGT) leads to effectiveness of scale parameter on equations of motion and the obtained results. The governing equations are derived by Hamilton's principles. A parametric study is presented to examine the effect of various parameters on vibrational behaviour of osteon. The results can also be regarded as a benchmark in vibration analysis behavior of osteon as bone unite.

• Korean Journal of Computational Design and Engineering
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• v.22 no.2
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• pp.172-180
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• 2017

The fractal structures, which include Sierpinski and Pascal triangular fractals, have provided many mathematical interests. In this study, the hydrodynamic and mechanical properties of the triangular fractals were investigated, and their application to the design of various artificial bone scaffolds has been implemented via CAD modeling, computational analysis and mechanical testing. The study proved that the Sierpinski and Pascal triangular fractal structures could effectively be applied to bone scaffold design and manufacturing regarding permeability and mechanical stiffness.

• Journal of the Korean Data and Information Science Society
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• v.16 no.4
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• pp.1017-1026
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• 2005

We consider the problem of modeling count data where the observation period is determined by the survival time of the individual under study. We assume random effects or frailty model to allow for a possible association between the death times and the counts. We assume that, given a random effect, the death times follow a Weibull distribution with a rate that depends on some covariates. For the counts, given the random effect, a Poisson process is assumed with the intensity depending on time and the covariates. A gamma model is assumed for the random effect. Maximum likelihood estimators of the model parameters are obtained. The model is applied to data set of patients with breast cancer who received a bone marrow transplant. A model for the time to death and the number of supportive transfusions a patient received is constructed and consequences of the model are examined.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.9.1-9.9
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• 2016

Background: As dental implants receive masticatory stress, the distribution of stress is very important to peri-implant bone homeostasis and implant survival. In this report, we created a saddle-type implant and analyzed its stability and ability to distribute stress to the surrounding bone. Methods: The implants were designed as a saddle-type implant (SI) that wrapped around the alveolar bone, and the sizes of the saddles were 2.5, 3.5, 4.5, and 5.5 mm. The X and Y displacement were compared to clarify the effects of the saddle structures. The control group consisted of dental implants without the saddle design (CI). Using finite element modeling (FEM), the stress distribution around the dental implants was analyzed. Results: With saddle-type implants, saddles longer than 4.5 mm were more effective for stress distribution than CI. Regarding lateral displacement, a SI of 2.5 mm was effective for stress distribution compared to lateral displacement. ASI that was 5.6 mm in length was more effective for stress distribution than a CI that was 10 mm in length. Conclusions: The saddle-type implant could have a bone-gaining effect. Because it has stress-distributing effects, it might protect the newly formed bone under the implant.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.151-156
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• 2016

Purpose: The dental implant should be enough to endure chewing load and it's required to have efficient design and use of implant to disperse the stress into bones properly. This study was to evaluate the stress distribution on a supporting bone by lengths and diameters of the implant fixture. Methods: The modeling and analysis of stress distribution was used for the simple molar porcelain crown model by Solidworks as FEM program. It was designed on applying with tightening torque of 20 Ncm of a abutment screw between a cement retained crown abutment and a fixture. The fixtures of experimental model used 10, 13mm by length and 4, 5mm by diameter. A external vertical loading on the two buccal cusps of crown and performed finite element analysis by 100 N. Results: The maximum von Mises stress(VMS) of all supporting bone models by fixture length and diameter were concentrated on the upper side of supporting compact bone. The maximum stress of each model under vertical load were 164.9 MPa of M410 model, and 141.2 MPa of M413 model, 54.3 MPa of M510 model, 53.6 MPa of M513 model. Conclusion: The stress reduction was increase of fixture's diameter than it's length. So it's effective to use the wider fixture as possible to the conditions of supporting bone.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1273-1281
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• 2014

Tissue engineering is an emerging research field that has the potential to restore, regenerate and repair damaged bone tissue and organs. Tricalcium phosphate and hydroxyapatite biomaterials-based calcium phosphate are excellent materials that have both osteoconduction and biocompatibility for bone tissue regeneration. In this study, solution structures were successfully fabricated using a fused deposition modeling system based on deposition and heating devices. The morphology characteristics of the bioceramic scaffolds sintered at a temperature of $1,300^{\circ}C$ were analyzed by scanning electron microscopy. The effects of various blended TCP/HA ratio on the microstructure and shrinkage were studied. The mechanical properties of the scaffolds were measured using a compression testing machine from stress-strain curves on the crosshead velocity of 1 mm/min. The fabricated scaffolds were evaluated by cell proliferation tests of MG-63 cells. The results of this study suggest that the blended TCP(75 wt%)/HA(25 wt%) scaffold is an appropriate scaffold for bone tissue regeneration.

• Journal of dental hygiene science
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• v.18 no.2
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• pp.130-135
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• 2018

The aim of this study was to investigate the role of osteal macrophages (osteomac) and osteocytes in bone remodeling using a mathematical model. We constructed the bone system with pre-osteoblasts, osteoclasts, osteocytes, and osteomac. Each link of the parameters and ordinary differential equations followed the Graham's model in 2013 except for the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts. We simulated the changes in each cell and bone volume according to the changes in the parameters of osteomac signaling and osteocytes signaling. The results showed bone volume was unstable and decreased gradually when the effectiveness of osteocytes and osteomac dropped below a certain level. When the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts had a value less than 1, bone volume increased with the increase in the parameter of osteomac signaling to link preosteoblasts and osteoblasts. Moreover, although the parameter of osteocytes signaling to link preosteoblasts and osteoblasts, increased in case of a small parameter of osteomac signaling, bone volulme decreased. If the parameters of osteomac signaling to link preosteoblasts and osteoblasts were over a certain level, bone volume was positively maintained, despite the parameter of osteocyte signaling to link preosteoblasts and osteoblasts. We suggested the osteomac may affect bone remodeling and may play an important role in bone cell network.

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.67-74
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• 2020

PURPOSE. This study evaluated the influence of prosthesis weight and number of implants on the bone tissue microstrain. MATERIALS AND METHODS. Fifteen (15) fixed full-arch implant-supported prosthesis designs were created using a modeling software with different numbers of implants (4, 6, or 8) and prosthesis weights (10, 15, 20, 40, or 60 g). Each solid was imported to the computer aided engineering software and tetrahedral elements formed the mesh. The material properties were assigned to each solid with isotropic and homogeneous behavior. The friction coefficient was set as 0.3 between all the metallic interfaces, 0.65 for the cortical bone-implant interface, and 0.77 for the cancellous bone-implant interface. The standard earth gravity was defined along the Z-axis and the bone was fixed. The resulting equivalent strain was assumed as failure criteria. RESULTS. The prosthesis weight was related to the bone strain. The more implants installed, the less the amount of strain generated in the bone. The most critical situation was the use of a 60 g prosthesis supported by 4 implants with the largest calculated magnitude of 39.9 mm/mm, thereby suggesting that there was no group able to induce bone remodeling simply due to the prosthesis weight. CONCLUSION. Heavier prostheses under the effect of gravity force are related to more strain being generated around the implants. Installing more implants to support the prosthesis enables attenuating the effects observed in the bone. The simulated prostheses were not able to generate harmful values of peri-implant bone strain.

• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.258-264
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• 2012

Purpose: This review aims at introducing 3 modeling approaches classified into 3 categories based on the purpose (estimation or prediction), structure (linear or non-linear) and phase (steady-state or dynamic-state); 1) statistical approaches, 2) kinetic modeling and 3) mechanistic modeling. We hope that this review can be a useful guide in the model-based approach of calcium metabolism as well as illustrates an application of engineering tools in studying biosystems. Background: The meaning of biosystems has been expanded, including agricultural/food system as well as biological systems like genes, cells and metabolisms. This expansion has required a useful tool for assessing the biosystems and modeling has arisen as a method that satisfies the current inquiry. To suit for the flow of the era, examining the system which is a little bit far from the traditional biosystems may be interesting issue, which can enlarge our insights and provide new ideas for prospective biosystem-researches. Herein, calcium metabolic models reviewed as an example of application of modeling approaches into the biosystems. Review: Calcium is an essential nutrient widely involved in animal and human metabolism including bone mineralization and signaling pathways. For this reason, the calcium metabolic system has been studied in various research fields of academia and industries. To study calcium metabolism, model-based system analyses have been utilized according to the purpose, subject characteristics, metabolic sites of interest, and experimental design. Either individual metabolic pathways or a whole homeostasis has been modeled in a number of studies.

• Biomolecules & Therapeutics
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• v.19 no.1
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• pp.70-76
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• 2011

Bone remodeling is a dynamic process involving a constant balance between osteoclast-induced bone resorption and osteoblast-induced bone formation. Osteoclasts play a crucial homeostatic role in skeletal modeling and remodeling, and destroy bone in many pathological conditions. Previously, we reported that the hexane soluble fraction of Ficus carica inhibited osteoclast differentiation. Poly unsaturated fatty acids, such as ethyl docosahexaenoate (E-DHA), docosahexaenoic acid (DHA), cis-11,14-eicosadienoic acid (EDA) and eicosapentaenoic acid (EPA), were identified from the hexane soluble fraction of Ficus carica. Among them, E-DHA most potently inhibited osteoclastogenesis in RAW264.7 cells. E-DHA reduced the activities of JNK and NF-$\kappa}B$. E-DHA suppressed the expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1). Interestingly, DHA increased the activity of alkaline phosphatase and expression of bone morphogenetic protein 2 (BMP2) more than E-DHA in MC3T3-E1 cells, suggesting that DHA may induce osteoblast differentiation. The data suggests that a combination of E-DHA and DHA has potential use in the treatment of diseases involving abnormal bone lysis, such as osteoporosis, rheumatoid arthritis and periodontal bone erosion.