Medical and dental devices

Standards ISO 10993 -5 1992 and EN 30993 -5 1994. Biological testing of medical and dental devices. Tests for cytotoxicity in vitro methods. 

The excellent hydrolytic stability of polysulfones makes them an ideal choice for use in a variety of medical and dental devices. The hydrolytic stabihty allows use in durable medical devices and components that have to be sterilized in a steam autoclave, sometimes hundreds of times over the hfe of the component. Such components include sterdization trays and cases, as well as parts of the surgical instruments themselves, such as the instrument handles. Traditionally, metals such as stainless steel have been used for this purpose. But metals are being replaced by thermoplastic materials. The use of plastics offers the ability to customize designs and colors as well as to mass-produce in a more economical fashion. For large parts, such as surgical instrument sterihzation trays, the weight... 

Base metals and alloys used in medical and dental devices are corrosion-resistant due to the presence of an oxide film on the surface that is protective [49]. These materials are not corrosion-resistant initially as is evident from their positions in the electromotive force series. The galvanic series, a listing of electrode potentials measured in seawater, indicates the changes in the noble and active tendencies of these materials in practical use for this given environment. Passivity is dependent on environmental factors such as solution pH, temperature, ions, oxygen, etc. Some ways of minimizing corrosion of these materials follow. Others are given in the discussion of the types of corrosion that can occur. 

PMMA is a versatile material because of its transparency and durability, and it has been widely used in a broad range of fields, such as lenses for glasses, panels for building windows, skylights, signs and displays, liquid-crystal displays (LCD), and furniture. Different methacrylate polymers are extensively used in medical and dental devices where purity and stability are critical to performance. 

Many medical and dental devices are now being assembled with cyanoacrylates to eliminate costly molding procedures. Cyanoacrylates are also being employed to eliminate the toxic solvents commonly used to bond flexibil-ized PVC in tubing joints. 

A flame-resistant copolymer consisting of 4 -biphenol polysulfone and biphenol A was prepared by El-Hibri et al. (4) and used as a medical or dental device as a steam sterilizable medical tray container. 

Another application for tantalum alloys is in medical and dental applications. The metal has no effect on body tissues. It is used in artificial hips, knees, and other joints. Pins, screws, staples, and other devices used to holds bones together are also made of tantalum alloys. 

The fourth environmental source of radiation is from exposure to medical diagnostic and therapeutic devices. X-ray exposures used for medical and dental diagnosis, and thera-... 

A number of important characteristics must be taken into consideration in addition to the efficacy of the products antimicrobial treatment. Biocompatibility is one of those characteristics. According to the International Organization for Standardization (ISO) 10993-1, Biological Testing of Medical and Dental Materials and Devices, all device materials must undergo cytotoxicity, sensitization and irritation testing as a minimum. 

In 1996, the European Union (EU) required all manufacturers to have a quality system compliant with ISO 9000 and demonstrate that the products met the requirements of the Medical Device Directive (for safety) in order to gain the right to carry the CE mark. All dental products sold within the EU are required to have the CE mark and to comply with the appropriate ISO standard if one existed. The EU adopted ISO 13485, a quality system for the medical and dental industries superseding ISO 9000 the EDA accepted the use of ISO 13485. 

Latex is present in many medical devices, including surgical and examination gloves, catheters, intubation tubes, anesthesia masks, and dental fillers. Reported allergic reactions range from contact urticaria to anaphylaxis (1). 

Potential applications of this device are to be found in medicine, dentistry and areas of industry. The most obvious promise of this unique unit is in medical or dental emergencies and other field use where a quick fluoroscopic examination is desired such as, (1) examination of a football player s possible bone injury on the football field (2) root canal analysis and possible monitoring of surgical procedures and (3) industrial detection of welding defects or gas leaks in pipes. 

NASA is working with several research institutes in the dental and medical field to clinically evaluate the Lixiscope. The commercialization potential of this device is high. We say this only because many medical and other manufacturing companies have inquired about the availability of the device. The Department of Defense has identified many potential applications, individual practitioners and veterinarians have inquired as to its availability. The experience and information gained from the clinical field evaluations mentioned earlier will be invaluable to potential manufacturers in the commercialization of this technological "Spin-Off" from NASA. 

Bismuth compounds are added more and more to special polymers for bone implants and dental prothetic devices in order to make them detectable to X-rays. Diagnostic devices for medical purpose have been using the bismuth-germanium oxide crystals to neutralize lethal gamma rays and improve overall imaging. Basic bismuth salicylate is used to impart a pearly surface to polystyrene and phenol-formaldehyde resins. 

Ideally, materials for medical and paramedical applications should be tested or evaluated at three level (1) on the ingredients used to make the basic resin, (2) on the final plastic or elastomeric material, and (3) on the final device. Organizations such as the Association for the Advancement of Medical Instrumentation, the U.S.A. Standard Institute, and the American Society for Testing and Materials (F4 Committee) have developed toxicity testing programs for materials used in medical apphcations. The American Dental Association has recommended standard procedures for biological evaluation of dental materials [74]. 

Polymers are the most versatile class of biomaterials, being extensively used in biomedical applications such as contact lenses, pharmaceutical vehicles, implantation, artificial organs, tissue engineering, medical devices, prostheses, and dental materials [1-3]. This is all due to the unique properties of polymers that created an entirely new concept when originally proposed as biomaterials. For the first time, a material performing a structural application was designed to be completely resorbed and become weaker over time. This concept was applied for the... 

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