Polymeric implants natural

These polymeric materials are fabricated to mimic the shape of natural bone, in a form referred to as a scaffolding. The scaffolding provides open spaces in which the body s osteoblasts can begin the regeneration of new hone. When regeneration is complete, the new bone can take over the structural chores temporarily performed by the bone implant. 

Numerous microfabrication techniques have been used to produce a wide range of implantable and oral drug delivery systems using materials ranging from silicon, glass, silicone elastomer, and plastics. Fabrication techniques have rapidly evolved to produce nanoscale objects and therapeutic systems using polymeric materials as the substrate due to their biodegradable nature. There are a number of different synthetic polymer systems that have been developed for this type of application, and the most common ones are listed below ... 

Adverse tissue response is usually higher for lower molecular weight polymers, and the presence of free monomer is usually cytotoxic. Many additives used in polymers give a strong, adverse tissue reaction due to a combination of their low molecular weight, higher mobility, moderate solubility in some body fluids, and their relatively reactive and toxic natures. For this reason, the use of plasticizers and/or stabilizers is ill-advised for biomedical polymers. In a similar manner, it is advantageous to remove the polymerization catalysts from the polymer before use as an implant material. 

Dental Polymers. Every year nearly a half billion dental fillings are done, and over a million dentures are constructed. Most of the materials used in each of these cases are polymeric. In addition, over 300,000 dental implants are made each year with either ceramics or polymers (1). The majority of the dental fillings and dentures are made from various copolymers of methyl methacrylate with other acrylics, although some other polymers, such as polyurethanes, vinyl chloride-vinyl acetate-methacrylate copolymers, vulcanized rubber, and epoxies, have been used to some extent. One major problem is aesthetics—the prosthesis must look natural and not discolor (by photoinduction or staining) to any great extent. 

Biomedical materials include metals, ceramics, natural polymers (biopolymers), and synthetic polymers of simple or complex chemical and/or physical structure. This volume addresses, to a large measure, fundamental research on phenomena related to the use of synthetic polymers as blood-compatible biomaterials. Relevant research stems from major efforts to investigate clotting phenomena related to the response of blood in contact with polymeric surfaces, and to develop systems with nonthrombogenic behavior in short- and long-term applications. These systems can be used as implants or replacements, and they include artificial hearts, lung oxygenators, hemodialysis systems, artificial blood vessels, artificial pancreas, catheters, etc. 

Synthetic rubbers were developed to substitute for natural rubber. The Ziegler-Natta types of stereospecific polymerization techniques have made this variety possible. The synthetic rubbers have rarely been used to make implants. The physical properties vary widely due to the wide variations in preparation recipes of these rubbers. 

Implanted biomaterials or medical devices are subjected to the surrounding host environment, which contains biochemical molecules such as enzymes [41,42], free radicals, peroxides [43], and hydrogen ions secreted by inflammatory cells and infecting microbes [44-46], The phagocytic mechanism of inflammatory cells such as neutrophils and macrophages has naturally evolved as a defense strategy for the body to ensure the removal of undesired foreign objects. Therefore, the potent biochemical actions of the secreted species can result in the unintended breakdown of solid-phase polymeric components of implanted devices over an extended period of time (months or years) [45],... 

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