VAD ÄR SILIKON?

Följer, men tror tyvärr att det kan vara svårt att få ett utförligt svar då tillverkningen av tex endast silikonet kan ske på så många olika vis

Testa kontakta socialstyrelsen, det är väl de som undersöker o godkänner implantat? Då borde de ha en utförlig lista på exakt innehåll

http://www.smw.ch/content/smw-2012-13614/

Silicones [3] should not be confused with the chemical element, silicon, which is part of the composition of silicones. Silicones are peculiar. Unlike many other silicon-containing compounds or materials (e.g., SiO2, quartz mineral) silicones do not occur in nature. They are entirely synthetic. They were first synthesised ca. 1900, and the term “silicones” was invented to describe them. Silicones are polymerised siloxanes (a.k.a. polysiloxanes). They are mixed inorganic-organic polymers with the chemical formula (R2SiO)n where R is an organic side group (e.g., methyl, CH3) attached to a siloxane ...-Si-O-Si-O-Si-O-... “backbone” or chain (fig. 2A, B). The specific example shown, polydimethylsiloxane (PDMS), is the most common polysiloxane [4]. Since the chains must be terminated, the complete PDMS formula is CH3[Si(CH3)2O]nSi(CH3)3. PDMS is an oily, sticky liquid with a viscosity that increases as the average chain length (molecular weight) is increased.

PDMS is the basis for the both breast implant silicone gel and the silicone rubber sac or shell which contains the gel. The molecular weight of PDMS (or any polymer) is an average, and thus some PDMS molecules will be far shorter than the average – or even cyclic rather than linear. This is important to the behaviour of PDMS in breast implant gels as discussed later.

Silicones can be liquids, gels, elastomers (rubbers) and even hard plastics. Production of silicones starts with sand (fig. 3) and is accomplished by varying the -Si-O-Si- chain length, using different organic side groups, and chemically cross-linking the polymer chains. The siloxane backbone, due to its large bond angles and bond lengths (fig. 4) is much more flexible than polymers with a carbon backbone (e.g. polyethylene). As a result all silicones are rubbery to varying extents. Liquid PDMS also has especially peculiar mechanical properties. It runs and flows if poured slowly, and spreads under the influence of gravity. However, if deformed rapidly, the flexible polymer chains easily become entangled. As a result viscous forms of PDMS can be molded by hand into a ball – which will bounce if thrown against a hard surface. Silly Putty® is liquid PDMS whose viscosity has been increased by reacting it with boric acid.

The inorganic siloxane backbone also causes silicones and silicone-based materials to have other special properties. Although the -Si-O- linkage is flexible, it is extremely chemically stable, as is the bond between Si and O in quartz mineral (silica, SiO2). Thus silicones can be viewed as liquid or solid polymeric materials which have some properties of ceramics. These include:

–  low thermal conductivity;

–  high thermal stability – chemical and physical properties change little from −100 to +250 °C;

–  high chemical resistance to attack by oxygen, ozone, and ultraviolet light.

For medical use, a consequence of thermal stability and resistance to chemical attack is that many silicone-based materials (e.g., silicone rubber) can be autoclave sterilised without altering their structure or properties.

Figure 3 http://www.smw.ch/fileadmin/smw/images/SMW-13614-Fig-03.jpg

Flow chart of the process – starting with sand – for making siloxane-based materials, including silicone rubber and silicone gel used in breast implants. Source: Wikimedia Commons, © Naweedkhan.

Det var allt jag kunde hitta i alla fall, vet inte om det kanske är av intresse?  Du kan ju gå in och läsa på sidan jag länkande, stod ganska mycket där.

PIP-implantaten var aldrig FDA* godkända, även om de var CE godkända.

*Food and Drug Administration, FDA, är den amerikanska livsmedels- ochläkemedelsmyndigheten med ansvar för mat, kosttillskott, läkemedel, kosmetika, medicinsk utrustning med mera.

Inom bland annat medicinteknisk industri talas ofta om produkter som uppfyller FDA:s lagkrav, kallade Quality System Regulation, QSR. FDA gör kontinuerliga och ibland oanmälda inspektioner av fabriker för att se till att kraven i QSR-lagen följs.

FDA anses allmänt vara en ”tuff” myndighet och får därför ibland kritik av läkemedelsbolag som blir missnöjda till exempel för att deras preparat inte godkänns.

När det gäller FDA-godkända bröstimplantat finns i Sverige bland annat Natrelle. Detta är implantat som ofta används på de kliniker som är måna om att nå ett bra resultat för sina patienter.