Bone tissue engineering (BTE) plays an important role in treating bone diseases related to osteoporosis and other orthopedic treatments. Although several methods are used in orthopedic surgery, some bone transport methods such as autografting and allografting have a certain number of disadvantages. Both are expensive methods and they can be exposed to infections and diseases. Therefore, in stead of using these potential risky methods, bone tissue engineering process are used to treat in orthopedic treatments. In general, both tissue engineering and bone tissue engineering have major constituents including stem cells, scaffold, bioreactors and growth factors.
2.1.1 Scaffolds Tissue defects in bone tissues tentatively need a new environment in order to provide basic requirements such as water resources, aliments, cytokines and growth factors until new bone tissue are restored. Scaffolds which has particular structure, are assigned as tentative matrix for cell propagation and ECM accumulation in damaged bone tissue. In addition, scaffold must have some significant features in order to adapt for bone tissue engineering because these features have an impact on cellular fate processes. There are several
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Growth factors are cytokines that are assigned as signalling molecules and most of different cell types sectarianize them. They encourage or obstruct cellular fate processes and they play an a significant role in tissue formation. Bone tissues comprise of plethora of growth factors and this has been involved in osteogenesis. Some essential growth factors which include bone morphogenetic proteins (BMPs), transforming growth factor beta (TGF-β), fibroblast growth factors (FGFs), insuline growth factor I and II (IGF I/II) and platelet derived growth factor (PDGF) are promising for bone tissue engineering applications (Rose & Oreffo,
However some of the basic bone functions include storing of crucial nutrients, minerals and lipids, producing red blood cells for the body, protect the organs such as heart, ribs and the brain, aide in movement and also to act as a buffer for pH. With the differences in all of the bones there are four things that remain the same in each bone, their cells. Bones are made up of four different cells; osteoblasts, osteoclasts, osteocytes and bone lining cells. Osteoblasts produce and secrete matrix proteins and then transport the minerals into the matrix. Osteoclasts are responsible for the breaking down of tissue. The osteoblasts and osteoclasts are both responsible for remodeling and rebuilding of bones as we grow and age. The production of osteoclasts for resorption is initiated by the hormone, the parathyroid hormone. Osteocytes are the mature versions of osteoblasts because they are trapped in the bone matrix they produced. The osteocytes that are trapped continue making bone to help with strength and the health of the bone matrix. The bone lining cells are found in the inactive bone surfaces which are typically found in
Many individuals have different views surrounding cochlear implants. Most of the Deaf community tends to be against them whereas most of the hearing community tends to be in favor of them. It is important to understand not only want a cochlear implant is, but how the different communities view the implants so that we can gain a better understanding of Deaf culture.
So far, various techniques have been used for reconstruction and regeneration of maxillary and mandibular bone defects. Autogenous bone grafting, guided bone regeneration (GBR), distraction osteogenesis and nerve transpositioning are among these regenerative techniques (1-8). Decision making for the treatment could be influenced by the type, size and location of the bone defects (2, 3, 9, 10). GBR had high success rate in treating small alveolar defects such as dehiscence or fenestration. Regenerative bony walls around the defect with ingrowing blood vessels can begin osteogenesis (11) larger bone defects with insufficient regenerative walls and an low quality avascular bed need varied amount of autogeneous bone graft from extra oral or intra oral donor sites, however, the patient may suffer from complications in donor site as well as bone graft resorption.(10, 12-15)
In orthopedic surgery, iliac bone graft which is commonly used for treatment nonunion or spinal fusion is contained multipotential stem cells or mesenchymal progenitor cells. These cells are found approximately 1 in 10,000 nucleated cells in the bone marrow. Friedenstein et al. (1970) reported that a rare population of cells was found by plastic-adherent ability (Friedenstein et al., 1970). These cells are capable of proliferation and mesenchymal lineages differentiation (Pittenger et al., 1999, Caplan, 1991). Unique antigens of MSCs (hMSCs) are controversy and the limited popularity of sorting cells techniques are not as widely used as gradient media in MSC isolation. Most MSC populations have been isolated by plastic adherent ability which is similar to that originally used by Friedenstein. Direct BM plating method is commonly used for cells from small animal (Lennon and Caplan, 2006, Nadri et al., 2007) but in human bone marrow, Density gradient centrifugation is the most commonly used method for isolating MSCs.
Some ceramics are used in orthopaedic applications such as bone repair, bone augmentation and joint replacement but their use in this field is not as extensive or widespread as metals and polymers because ceramics have poor fracture toughness. This severely limits the use of ceramics in load bearing applications (Davis, 2003).
Titanium exhibits a variety of mechanical properties that allows it to be used in different applications. Titanium is extremely resistant to corrosion especially when in close proximity with different media such as human bone, synovial fluid and plasma. This is achieved through the use of a stable and insoluble oxide film that strongly adheres to the surface of titanium. Research has shown that titaniums resistance is considerably better than
The way 3D printing works is by taking virtual designs from a special computer aided design or modeling software and “splits” them into separate cross-sections for the machine to use as a guide. The printer then lays down successive layers of the liquid or powdered material required (metal, plastic, paper, ceramics etc.) and eventually builds the model through these series of cross sections, creating the object desired. This printing layer by layer slowly develops the object.
Osteoporosis is a serious disease that leads to a faster than normal loss of the bone density, which puts the bone at a higher risk for fractures. In order to understand the causes of Osteoporosis, it is important to understand how bones are formed. Bone is a living tissue that is made mainly of collagen, calcium phosphate, and calcium carbonate. The mixture of collagen and calcium gives the bone strength and flexibility. The body deposits new bones and removes old ones; moreover, there are two types of bone cells that control the reproduction of bones. Cells called osteoclasts breakdown bone tissues thus, damaging the bone. Once the damaged bone is removed, cells called osteoblasts, use minerals including calcium and phosphate from the blood stream to make new healthy bone tissues. In order for osteoblasts and osteoclasts to work properly, hormones such us thyroid, estrogen, testosterone, and growth hormones are
Spinal fusion stabilizes the spinal vertebra by fusing the disk spaces between the vertebra. The purpose of Lumbar fusion surgery is designed to help create solid bone between the adjoining vertebra. Classically Autograft bone has been used for fusion. This case study demonstrates the successful use of a synthetic bone graft called Signafuse. Signafuse is a moldable bone graft comprising a proprietary combination of patented bioactive glass particles and biphasic mineral granules suspended in a patented resorbable polymer carrier.
With the development of modern technologies, people enjoy their lives with higher level of quality. This results in the extension of average humane life time and the rapid changes of age structure of the population in the world. There are increasing demands for replacing the failed tissues on aged people. For example, if injury occurs on knees, the ability to flex the knee will be restricted due to pain. Deterioration of the knee joint would make it difficult to perform everyday activities. Even when you lie and sit, it still feels painful. Knee replacement surgery is a common solution to relief for the pains. These rapid increasing demands of implant demonstrate the new generation of implant materials with better mechanical properties and higher biological performance for the expectation of longer life.
In the articles a common goal was researchers feel that the loss and gain function of LRP5 affects bone formation, causes osteoporosis, and high bone mass. Bone formation forms cartilage growth and replacement by bone is responsible for most growth in vertebrates. Bones is living, growing tissue and it made of collagen and calcium phosphate that adds strength and hardness. However, Osteoporosis has become a major health problem due to unknown cause. When bone resorption occurs too quickly or when bone replaces occurs too slowly it known as osteoporosis. Researchers have compared images of a healthy bone and a bone with osteoporosis the difference among the two where the holes and spaces in them. A bone with osteoporosis holes and spaces were larger than a healthy bone.
There are numerous factors which can affect dimensions of subsequent casts on repetitive pouring. These include the process of polymerization (7), temperature (1), and material used to fabricate the replica or working cast (1). Although, PVS impression materials have demonstrated superior dimensional stability when compared with other elastomeric materials due to no releasing any by-products (8), it had been reported that the dimensional accuracy of a material is time dependent. A material may be highly dimensionally accurate soon after its initial polymerization but less accurate after the storage for a period of time (9). On the other hand, PVS impression materials have chosen as the impression material in many clinical situations because they possess excellent physical properties and handling characteristics
To understand the conflicting issues brought about by this new technology, one must know the basic functions and concepts of 3D printing. The key idea of 3D printing or additive manufacturing (AM) is "using computer-aided design (CAD) software to design a three-dimensional image of what you want to produce" (Ranaldi). Once you have the CAD software, 3D printer purchased from manufactures, and a design file, all that's left is to purchase the material needed for your design. Although the process described seems very costly, some advantages from 3D printing such as greatly reduced production time, low waste production and easy accessibility makes up for much of the initial start up costs. In short, " [Additive manufacturing] simplifies the manufacturing process by building pre-assembled systems: a clock with all its gears in place" (Haxel, 5)...
The idea was to improve 3d printer with special technology, a single printer, with multi material features, can transform from any 1D strand into 3d shape, 2d surface into 3d shape or morph from one 3d shape into another. The shape of 3d technology is basic mode for 4d. Objet Connex multi-material technology is an 3D printing important part of his work – and is being used extensively in this new process. The Connex multi material technology allows the researchers to program different material properties into each of the various particles of the designed geometry and harnesses the different water-absorbing properties of the materials to active the self-assembly process. With water as its activation energy, this technique promises new possibilities for embedding programmability and simple decision making into non-electronic based materials.
The field of regenerative medicine encompasses numerous strategies, including the use of materials and de novo generated cells, as well as various combinations thereof, to take the place of missing tissue, effectively replacing it both structurally and functionally, or to contribute to tissue healing[29]