Remodeling Cycle

An imbalance in the regulation of bone remodeling's two contrasting events, bone resorption and bone formation, results in many of the metabolic bone diseases, such as OSTEOPOROSIS.

Osteoblast- cells which build bone by removing calcium and phosphates form the blood in the presence of the enzymes alkaline phosphates secrete by

The skeletal system, while appearing inert at first glance, is a dynamic organ responsible for a number of vital functions in the body; including but not limited to providing protection and support to other organ systems, as well as permitting movement through collaboration with the muscular system. At the cellular level, bone provides a reservoir of growth factors and cytokines, maintains the acid-base balance and mineral homeostasis, and is the site of hematopoeisis. Like other connective tissue, bone has both a cellular and an extracellular matrix component. The matrix is made up of collagen fibers and noncollagenous proteins, with type I collagen accounting for ~90% of total protein, and the noncollagenous osteocalcin, osteopontin, and bone sialoprotein, and others making up the other 10%. In contrast with other connective tissue, the extracellular matrix of bone is mineralized physiologically, though the deposition of layers of carbonated hydroxyapatite. This mineral component, making up 50-70% of bone, provides bone 's characteristic mechanical rigidity and strength (Clarke 2008). Elasticity and flexibility are due to the organic matrix, which makes up another 20-40%, lending bone incredible resilience without compromising its strength, and another 5-10% of bone is water.

Longitudinal bone growth occurs at the epiphyseal plate, which is a thin layer of cartilage between the epiphyseal and metaphyseal bone at the distal ends of the long bones. Bone growth is the result of maturation, growth of chondrocytes, their production of bone matrix, and finally calcification (47). The growth plate is a complex structure consisting of different layers of cells, as shown in figure 3. The most immature cells, the stem cells, are found towards the epiphyseal end of the growth plate in the stem cell zone, or resting zone; the proliferating zone contains more mature chondrocytes and the hypertrophic zone contains the larger chondrocytes. The resting stem cells in the resting zone are recruited, whereupon proliferation and differentiation

Bone is a living tissue and made up of cartilage. Fibrodysplasia ossificans progressiva bone appears as normal bone tissue, but it develops in the wrong places. Osteogenesis and ossification are medical terms which refer to the formation of bone. Most bones in the human body grow and heal up after a break through endochondral bone formation, which is how FOP bones grow. Cartilage forms first and then the bone will eventually take the place of cartilage.

Mature long bones consist of 3 distinct parts which are epiphysis, metaphysis and diaphysis. The epiphysis located at the both ends of long bone and composed of thin compact bone shell with a large amount of bony struts (trabecular bone) for supporting the cortical shell. In fact, the bony struts which located below the compact bone also aid as shock absorber. The thicker shell of compact bone which located just below a joint is known as the subchondral bone. It helps to support the hyaline articular cartilage of the joint just above it and have some lacks in organization of cortical bone as it is not true cortical bone. The epiphysis also serves as an attachment region in many bones includings joint capsular, ligaments, and some tendons.

white blood cells are made. Lastly, the bones provide storage for essential minerals such as calcium

Osteoblast plays an important role in bone mineralization. Before the organic matrix is mineralized, it is called osteoid. Osteoblasts buried deep in matrix are called

It is when the cell osteoblasts are activated on the surface of the bone and creates layers of cells called osteoclasts which consume cartilage.

Bones in the human body form in the process called ossification. There are four stages in ossification, 1.) Embryonic bone formation; 2.) Bone growth throughout life starting in infancy through adulthood; 3.) Bone remodeling, and 4.) Fracture (breaks in the bone) repair.

Bones are the organs that hold the framework of the human body. Not only do they keep our bodies erect, they also house and protect organs, provide mineral and triglyceride storage, allow movement, produce hormones and blood cell formation (hematopoiesis). Cells of bone tissue contains major cells that build bone from matrix secretion (osteoblast) and breaks down bone (osteoclast). Both cells are a vital factor in bone growth, healing, and remodeling. Other important cells include osteogenic cells, osteocytes, and bone lining cells. Osteogenic cells mitotically divide and later form into osteoblasts. Osteocytes are aged bone cells that no longer divide, but do perform as stress receptors and respond to mechanical weight and impact by communicating with osteoclasts and osteoblasts to promote bone remolding. Finally, bone-lining cells work cohesively with osteocytes to maintain bone matrix.

Bone is the substance that forms the skeleton of body. It is composed chiefly of calcium phosphate and calcium carbonate. It is also serves as a storage area for calcium, playing a large role in calcium balance in blood. The main function of bone is they support and protect various of organs in body, stores blood cell and store minerals. Bone can be categorized as a fragile part in body. The replacement and repair of bone due to accident, cancer or bone defect is a major clinical challenge which can be countered by bone grafting. Bone grafting or transplantation with artificial bone material is the solution for the problem [1].

The biological process of osseointegration following the creation of an osteotomy site includes blood clot formation and the release of growth factors (BMP’s, VEGF etc.); this is followed by new blood vessel formation (Angiogenesis). The presence of a fibrin scaffold between the osteotomy site and the surface of the implant serves as a transition between the bone marrow (where the osteoprogenitor cells are located) and the surface of the implant, which is a very important factor in the migration of osteoprogenitor cells into the bone-implant interface zone. When the cells get there, they begin the deposition of lamellar bone and then the formation of a more mature bone on the surface of the implant to achieve a good osseointegration. The reason

The two main age-related changes that are seen in this system pertain to the bones and soft tissues. Bone is the fundamental part

Decades ago, numerous studies toke place on bone growth and healing with the use of guided bone regeneration concepts. Bone has been considered as the one tissue with the greatest potential for regeneration among the many tissue in the body. A long time ago in 1889 senn reported that the present of decalcified bone could encourage healing of the bone defects (170). Guided bone regeneration is frequently used the same concept for hard tissue reconstruction (128, 171, 172). The treatment concept includes the application of occlusive membranes for the regeneration of osseous defects. The membrane induce osteogenic cell population coming from the parent bone tissue by excluding the non-osteogenic cell population from the surrounding soft tissues, thereby inhibit the osseous wound (173-176). Actually, the placement of mechanical membranes over the jaw bone defects resulted in effective results in rabbits (177) and over cranial defects in rats (178). Therefore, guided bone regeneration (GBR) was introduced as a therapeutic modality aiming to achieve bone regeneration, via the use of barrier membranes (87).