Figure - available from: Journal of Biomedical Materials Research Part B Applied Biomaterials
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Operative procedure on the maxilla in a canine. The maxillary's second and third incisors are extracted on both sides. After 12 weeks two cylindrical bone holes, which have 3 mm diameter and 4 mm depth, are drilled at intervals of 3 mm in the right maxilla of the canine. One of the two holes was filled with electrically polarized β‐TCP granules (the polarized group) and the other was with nonpolarized β‐TCP granules (the nonpolarized group). Four more weeks later, the same operative procedure is performed to implant electrically polarized and nonpolarized β‐TCP granules in the two drill holes on the contralateral left maxilla. Four weeks after the second implantation, the animals are sacrificed. The number of specimens harvested at 4 and 8 weeks postoperatively was six respectively in both polarized and polarized groups
Source publication
We succeeded in the electrical polarization of β‐tricalcium phosphate (β‐TCP) granules and performed an unprecedented attempt to implant them into maxillary bone defects in canines to confirm their ability to facilitate new bone formation. Two holes were drilled into each maxilla half of a canine and filled with electrically polarized and nonpolari...
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... Although 3D printing is an adapted technique for creating block-type BGs with ordered porous structures, it is unsuitable for manufacturing fine BGs because of its resolution and productivity [51][52][53][54][55][56]. Notably, dental treatments employ submillimeter BG granules [57][58][59][60][61][62][63]. Manufacturing dental BG granules with precisely controlled pore sizes and shapes using 3D printing is difficult. ...
Synthetic bone grafts are in high demand owing to increased age-related bone disorders in the global aging population. Here, we report fabrication of gear-shaped granules (G-GRNs) for rapid bone healing. G-GRNs possessed six protrusions and a hexagonal macropore in the granular center. These were composed of carbonate apatite, i.e., bone mineral, microspheres with ∼1-μm micropores in the spaces between the microspheres. G-GRNs formed new bone and blood vessels (both on the granular surface and within the macropores) 4 weeks after implantation in the rabbit femur defects. The formed bone structure was similar to that of cancellous bone. The bone percentage in the defect recovered to that in a normal rabbit femur at week-4 post-implantation, and the bone percentage remained constant for the following 8 weeks. Throughout the entire period, the bone percentage in the G-GRN-implanted group was ∼10% higher than that of the group implanted with conventional carbonate apatite granules. Furthermore, a portion of the G-GRNs resorbed at week-4, and resorption continued for the following 8 weeks. Thus, G-GRNs are involved in bone remodeling and are gradually replaced with new bone while maintaining a suitable bone level. These findings provide a basis for the design and fabrication of synthetic bone grafts for achieving rapid bone regeneration.
... Therefore, synthetic scaffolds with precisely controlled macropore size (200-300 μm) and micropore volume (0.1-0.2 g/cm 3 ) are required to achieve favorable bone regeneration. Granular, rather than blockish, scaffolds (<2 mm) are used in clinical dentistry because their defect sizes in bone are usually small [27][28][29][30][31][32][33][34]. Macroporous granules are more favorable than dense granules (DGs) for the rapid ingrowth of bone [35][36][37][38][39][40][41][42][43][44][45]. ...
Granular porous calcium phosphate scaffolds are used for bone regeneration in dentistry. However, in conventional granules, the macropore interconnectivity is poor and has varying size. Herein, we developed a productive method for fabricating carbonate apatite honeycomb granules with uniformly sized macropores based on extrusion molding. Each honeycomb granule possesses three hexagonal macropores of ∼290 μm along its diagonal. Owing to these macropores, honeycomb granules simultaneously formed new and mature bone and blood vessels in both the interior and exterior of the granules at 4 weeks after implantation. The honeycomb granules are useful for achieving rapid osteogenesis and angiogenesis.
... Wang et al. showed that β-TCP ceramic particles can accumulate by polarization large electric charges of ca. 1 mC cm -2 , which is 10 2 times larger than that required with HAp (10 μC cm -2 ) [12]. We also reported enhanced bone formation in canine maxilla when electrically polarized β-TCP was used [13]. However, the mechanism for the polarization of β-TCP is still controversial and requires clarification so that excellent polarizable β-TCP ceramics as biomaterials can be fabricated. ...
... Alternating current (AC) impedance conductivity of the Na-β-TCP pellets was calculated from the complex impedance measured in the frequency range of 1 to 10 MHz using an impedance/gain phase analyzer (SI 1260, Toyo Co. Ltd., Tokyo, Japan), as described previously [2][3][4]12,13,22,23]. Platinum was sputtered on both surfaces of the Na-β-TCP pellets, which were then clamped between a pair of platinum electrodes and tested from 350 to 650 • C at 50 • C intervals using a voltage of 2.0 V rms . ...
... In accordance with the electrical polarization process reported in previous studies [2][3][4]12,13,22,23], Na-β-TCP samples were electrically polarized in a DC field of 0.65 V/mm in air at 400 • C for 1 h. The samples were cooled down to room temperature under electric field polarization. ...
With the aim to understand electric polarization mechanisms of β-tricalcium phosphate as an advanced biomaterial, Na ion-substituted β-Ca3(PO4)2 (Na-β-TCPs) ceramics with controlled lattice vacancies were synthesized and structural refinement was performed by the Rietveld method. The Rietveld analysis revealed that Ca and vacancies at Ca(4) sites in the β-TCP structure decreased with an increase in Na substitution. Electrical measurements by the complex impedance method revealed that the conductivity and the activation energy calculated from Cole-Cole plots rapidly decreased to a constant value with an increase in Na substitution and decrease in vacancies. The thermally stimulated depolarization current (TSDC) curve of the electrically polarized Na-β-TCP showed one large peak at 530–610 °C. However, the accumulated charge decreased with an increase in Na ions and decrease in vacancies up to 2.37 mol%, after which it became constant. These results are consistent with the presumed formation of a dipole moment between aligned Ca²⁺ ions and their vacancies along the direction of the external polarization field applied at high temperature. We conclude that the large amount of stored charge in β-TCP caused by electrical polarization is due to the low site occupancy of calcium ions and vacancies at Ca(4) sites in the β-TCP structure, which is not the case for hydroxyapatite (HAp), as previously reported.
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Various bone graft products are commercially available worldwide. However, there is no clear consensus regarding the appropriate bone graft products in different clinical situations. This review is intended to summarize bone graft products, especially alloplastic bone substitutes that are available in multiple countries. It also provides dental clinicians with detailed and accurate information concerning these products. Furthermore, it discusses the prospects of alloplastic bone substitutes based on an analysis of the current market status, as well as a comparison of trends among countries. In this review, we focus on alloplastic bone substitutes approved in the United States, Japan, and Korea for use in periodontal and bone regeneration. According to the Food and Drug Administration database, 87 alloplastic bone graft products have been approved in the United States since 1996. According to the Pharmaceuticals and Medical Devices Agency database, 10 alloplastic bone graft products have been approved in Japan since 2004. According to the Ministry of Health and Welfare database, 36 alloplastic bone graft products have been approved in Korea since 1980. The approved products are mainly hydroxyapatite, β-tricalcium phosphate, and biphasic calcium phosphate. The formulations of the products differed among countries. The development of new alloplastic bone products has been remarkable. In the near future, alloplastic bone substitutes with safety and standardized quality may be the first choice instead of autologous bone; they may offer new osteoconductive and osteoinductive products with easier handling form and an adequate resorption rate, which can be used with growth factors and/or cell transplantation. Careful selection of alloplastic bone graft products is necessary to achieve predictable outcomes according to each clinical situation.
Bone degeneration associated with various diseases is increasing due to rapid aging, sedentary lifestyles, and unhealthy diets. Living bone tissue has bioelectric properties critical to bone remodeling, and bone degeneration under various pathological conditions results in significant changes to these bioelectric properties. There is growing interest in utilizing biomimetic electroactive biomaterials that recapitulate the natural electrophysiological microenvironment of healthy bone tissue to promote bone repair. This review first summarizes the etiology of degenerative bone conditions associated with various diseases such as type II diabetes, osteoporosis, periodontitis, osteoarthritis, rheumatoid arthritis, osteomyelitis, and metastatic osteolysis. Next, the diverse array of natural and synthetic electroactive biomaterials with therapeutic potential are discussed. Putative mechanistic pathways by which electroactive biomaterials can mitigate bone degeneration are critically examined, including the enhancement of osteogenesis and angiogenesis, suppression of inflammation and osteoclastogenesis, as well as their anti‐bacterial effects. Finally, the limited research on utilization of electroactive biomaterials in the treatment of bone degeneration associated with the aforementioned diseases are examined. Previous studies have mostly focused on using electroactive biomaterials to treat bone traumatic injuries. It is hoped that this review will encourage more research efforts on the use of electroactive biomaterials for treating degenerative bone conditions.
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Ceramics electrets of hydroxyapatite (HAp) have been developed for both power generators and artificial bones. However, the formation mechanisms of the HAp electrets have not yet been completely understood. In particular, it is unclear how the OH − ion dipoles in HAp lattices contribute to electret performance. Herein, we show that HAp with controlled OH − ion content exhibits excellent performance as an electret. We prepare OH−-defect-controlled HAp samples either by restricted dehydration during thermal process or by valence control through the substitution of Ca²⁺ with Nd³⁺. The experimental results prove that the electrets prepared by partially dehydrated HAp and Nd-substituted HAp with a small number of OH − ions showed better performance. Our results suggest that the OH − ion–dipole polarization contributes negatively to the electret performance.
This paper investigates the Microstructural and Mechanical properties of Wollastonite (CaSio3) ceramics incorporated with Titanium oxide (TiO2) and Hydroxyapatite (HA) composites preparation using Spark Plasma Sintering (SPS). And the influence of Sintering on CaSio3with additives at different temperatures ranging from 1150 °C to 1250 °C with heating rate of 100 °C/min holding time of 10 min are reported and discussed. The microstructure of the sintered samples was investigated by SEM microscopy, XRD Diffraction analyses which presented uniform distribution of the additives (TiO2/HA), having a maximum fine grain size of 32 nm. The mechanical tests were performed for hardness which was 67Hv and Compressive strength of 225Mpa were obtained at the sintering temperature 1250 °C. The superior results have been observed at the highest temperature, along with the addition of the additives (TiO2/HA) to the pure wollastonite over the physical and Mechanical properties.
