칼슘 포스페이트 골 시멘트에서의 테트라사이클린 방출 거동

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Improvement of osteogenic potential of biphasic calcium phosphate bone substitute coated with synthetic cell binding peptide sequences

Purpose : The aim of this study was to evaluate the improvement of osteogenic potential of biphasic calcium phosphate (BCP) bone substitute coated with synthetic cell-binding peptide sequences in a standardized rabbit sinus model. Methods : Standardized 6-mm diameter defects were created bilaterally on the maxillary sinus of ten male New Zealand white rabbits, receiving BCP bone substitute coated with synthetic cell binding peptide sequences on one side (experimental group) and BCP bone substitute without coating (control group) on the other side. Histologic and histomorphometric analysis of bone formation was carried out after a healing period of 4 or 8 weeks. Results : Histological analysis revealed signs of new bone formation in both experimental groups (4- and 8-week healing groups) with a statistically significant increase in bone formation in the 4-week healing group compared to the control group. However, no statistically significant difference in bone formation was found between the 8-week healing group and the control group. Conclusions : This study found that BCP bone substitute coated with synthetic cell-binding peptide sequences enhanced osteoinductive potential in a standardized rabbit sinus model and its effectiveness was greater in the 4-week healing group than in the 8-week healing group.ope

Improvement of osteogenic potential of biphasic calcium phosphate bone substitute coated with two concentrations of expressed recombinant human bone morphogenetic protein 2

Purpose : The aim of this study was to determine whether biphasic calcium phosphate (BCP) bone substitute with two different concentrations of Escherichia coli-expressed recombinant human bone morphogenetic protein 2 (ErhBMP-2) enhances new bone formation in a standardized rabbit sinus model and to evaluate the concentration-dependent effect of ErhBMP-2. Methods : Standardized, 6-mm diameter defects were made bilaterally on the maxillary sinus of 20 male New Zealand white rabbits. Following removal of the circular bony windows and reflection of the sinus membrane, BCP bone substitute without coating (control group) was applied into one defect and BCP bone substitute coated with ErhBMP-2 (experimental group) was applied into the other defect for each rabbit. The experimental group was divided into 2 subgroups according to the concentration of ErhBMP-2 (0.05 and 0.5 mg/mL). The animals were allowed to heal for either 4 or 8 weeks and sections of the augmented sinus and surrounding bone were analyzed by microcomputed tomography and histologically. Results : Histologic analysis revealed signs of new bone formation in both the control and experimental groups with a statistically significant increase in bone formation in experimental group 1 (0.05 mg/mL ErhBMP-2 coating) after a 4-week healing period. However, no statistically significant difference was found between experimental group 1 and experimental group 2 (0.5 mg/mL ErhBMP-2 coating) in osteoinductive potential (P<0.05). Conclusions : ErhBMP-2 administered using a BCP matrix significantly enhanced osteoinductive potential in a standardized rabbit sinus model. A concentration-dependent response was not found in the present study.ope

Improved bonding strength between TiO2 film and Ti substrate by microarc oxidation

Titanium (Ti) and its alloys have proved to be very suitable materials for load-bearing bioimplant applications. Unfortunately, Ti and its alloys exhibit poor osteoinductive properties like most metals. This drawback was recently addressed by modified titania (TiO2). However, the bonding strength between TiO2 and substrate is not very strong. Therefore, mechanical properties and biochemical stability are very important. Many techniques have been investigated for modifying the TiO2 layer. Microarc oxidation (MAO) represents a relatively new surface modification technique where thick, hard and anticorrosive oxide coatings can be easily and cost-effectively fabricated. In this study, various chemicals were used as the electrolyte for MAO. Hydroxyapatite (HA) suspension was prepared by dispersing HA powder in distilled water and adjusting the pH in the range of 4–11. Bonding strength between TiO2 film and substrate was determined by modified ASTM C-633 and the ability to form apatite was confirmed after MAO, by soaking in simulated body fluid (SBF). The bonding strength decreased when the electrolyte was changed, but increased with increasing voltage. Bioactivity was only present in NaOH-treated specimensope

Study on bioactivity and bonding strength between Ti alloy substrate and TiO2 film by micro-arc oxidation

In this study, the Ti alloy substrate was simultaneously coated with TiO2 film and hydroxyapatite using micro-arc oxidation, a relatively new surface modification technique where thick, hard, and anticorrosive oxide coatings can be easily and cost-effectively fabricated. Pulsed DC power and various voltages were applied to the Ti alloy substrate. Citric acid, ethylene diamine, and ammonium phosphate were also dissolved as electrolytes followed by the dispersion of hydroxyapatite nanoparticles into those prepared electrolytes. The effects of the composition and applied voltage on the bonding strength, bioactivity, cell attachment and cytotoxicity were investigated. It was observed that the simultaneously coated TiO2 and hydroxyapatite samples showed improved bioactivity, cell attachment and viability, while maintaining the bonding strength between the coated film and substrate.ope

Drug-loaded porous spherical hydroxyapatite granules for bone regeneration

Porous spherical hydroxyapatite (HAp) granules, which are not only can be used for bone void filler, but also drug delivery systems, were prepared using a liquid nitrogen method. Various pore and channel structures of spherical granules were obtained by adjusting the ratio of water to HAp powder and the amount of sodium chloride (NaCl). By using the water to powder ratio at 2.0 ml/g and the amount of NaCl at 15 wt% by powder, the spherical granules have optimal pore volume, micro-channel structure and strength to handle as well as the ability to work as a drug delivery system. When the NaCl content was 15 wt%, the micro-channel structure was changed, but the pore volume was maintained. For the drug release test, dexamathasone (Dex) was loaded as a model drug on the prepared HAp granules by the immersion method, and the drug release behavior was curved by a UV/vis spectrophotometer. As a result, different drug release behavior was observed according to micro-channel structural differences. Therefore, it was concluded that the NACl could be applied as the pore and micro-channel structure control agent. Porous spherical HAp granules, which were fabricated by a liquid nitrogen method, show potential as bone void filler with the ability of controlled drug releaseope

Bone Tissue Engineering by Using Calcium Phosphate Glass Scaffolds and the Avidin-Biotin Binding System

Highly porous and interconnected scaffolds were fabricated using calcium phosphate glass (CPG) for bone tissue engineering. An avidin-biotin binding system was used to improve osteoblast-like cell adhesion to the scaffold. The scaffolds had open macro- and micro-scale pores, and continuous struts without cracks or defects. Scaffolds prepared using a mixture (amorphous and crystalline CPG) were stronger than amorphous group and crystalline group. Cell adhesion assays showed that more cells adhered, with increasing cell seeding efficiency to the avidin-adsorbed scaffolds, and that cell attachment to the highly porous scaffolds significantly differed between avidin-adsorbed scaffolds and other scaffolds. Proliferation was also significantly higher for avidin-adsorbed scaffolds. Osteoblastic differentiation of MG-63 cells was observed at 3 days, and MG-63 cells in direct contact with avidin-adsorbed scaffolds were positive for type I collagen, osteopontin, and alkaline phosphatase gene expression. Osteocalcin expression was observed in the avidin-adsorbed scaffolds at 7 days, indicating that cell differentiation in avidin-adsorbed scaffolds occurred faster than the other scaffolds. Thus, these CPG scaffolds have excellent biological properties suitable for use in bone tissue engineering.restrictio

Drug release from porous hydroxyapatite spheres as a synthetic bone-graft material

Hydroxyapatite (HA) is the most commonly used synthetic bone-graft material due to the main component of bones and teeth. However, many research about combining the biological factors and drugs with HA have been performed since a few years ago. We investigated drug(dexamethasone) release behavior after loading to porous spherical HA granules according to the amount of water and sodium chloride as well as the structure of porous HA.restrictio

Fabrication of hollow hydroxyapatite spherical granules for hard tissue regeneration and alternative method for drug release test

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Development and in vitro assays of porous calcium polyphosphate granules

Porous calcium polyphosphate granules (CPPGs) for hard tissue regeneration were developed using amorphous calcium phosphate (CaP) glass particles. The glass particles were synthesised using a conventional glass melting technique, and the CPPGs were fabricated by a cement hardening process consisting of an acid–base reaction and a condensation reaction, which was developed in our previous studies. The pore sizes of the CPPGs were controlled using polymeric pore generators (porogens) of various sizes. The glass particles and CPPGs were analysed using X-ray diffractometry and Fourier transform infrared spectroscopy. The porosity of the CPPGs increased from 33.327% to 48.706% as the size of the porogens was decreased. To evaluate the cellular response to the developed porous CPPGs, cell proliferation and differentiation tests were performed, and an analysis of the relationship between the porosity and bioactivity was carried out. The results showed that both pore size and porosity influenced the osteogenic differentiation as well as the cell proliferation. This was due to the calcium ion release rate, which increased as the porosity increased and affected cellular behaviour. In conclusion, the porous CPPGs fabricated using amorphous CaP glass particles were shown to have potential as excellent bone graft materials.restrictio