Breast implants silicone rubber

Silicon (Si) Silicon is a lustrous silvery gray material. Because silicon conducts electricity, but not as well as a metal, silicon is classified as a semimetal. Crystals of pure silicon that have been doped with arsenic or gallium are known as semiconductors and are used to fabricate computer chips. Silicone rubbers are polymers containing silicon, oxygen, and various hydrocarbon groups, and are used in applications ranging from sealants to breast implants. 

The best-known example of this application is the mammary prosthesis, or replacement breast, which consists of a silicone rubber gel in a bag of silicone that has been preformed to match the contours of a natural breast after implantation. The replacement testicle uses the same basic materials in a different shape. Neither device performs any physiological function (1, 12). 

Permeability. Blon elastomer has much less diffusion of silicon oil and water than silicon rubber under the same testing conditions (ASTM D814). Comparative permeation rates are listed on Table VI. Applications demanding low permeable materials Include Implantation of encapsulated electronic devices and silicon oll-fllled breast prostheses. 

Siloxane polymers (better known in the commercial market as silicones) have widespread applications, a few of which are personal care products, greases, sealants, varnishes, waterproofing materials, synthetic rubbers and gas-permeable membranes such as those used in soft contact lenses. Medical applications are increasing in importance, although the use of silicone breast implants is a controversial issue because of claims of the migration of low molecular weight siloxanes from the implant into the surrounding body tissue. 

Brandon, HJ, Young, VL, Jenina, KL and Wolf, CJ, Variabihty in the properties of silicone gel breast implants, Plast Reconstruct Surg, 108(3), 647-655 (2001). Blow, CM (Ed), Rubber technology and manufacture, Newnes Butterworth, 135 (1971). 

Experience over a three year period with polytetrafluoroethylene (Proplast) is reported together with early results on chlorinated polyethylene which is claimed to have advantages over other available materials. The sunlight stability of facial prostheses presents an obvious problem and the behaviour of polyurethanes in this respect has been examined. Experimental reconstructive prostheses have involved for example silicone rubber in the repair of nasal septal perforation and ear reconstruction and polytetrafluoroethylene in frontal sinus reconstruction. Breast reconstruction and augmentation with silicone rubber and polyurethanes, tissue reaction to polyurethane coated implants, and the use of polyethylene in this type of surgery have been discussed. A useful review on silicone fluids (which are for example iiyected to improve scars ) has appeared. 

The convenient properties of liquid and solid dimethylpolysiloxanes (thermal and chemical stability, hydrophobicity, anti-adhesive behavior, etc.) make them suitable for a variety of technical applications in medicine. Especially pure preparations (Silastic ) have been used to construct artificial limbs, gullets, cardiac valves, trachea, etc., and in face-lifting. Silicon rubber breast implants, which are filled with a polysiloxane gel, have been used cosmetically. Synthetic arteries impregnated with silicon do not break or cause coagulation, they are flexible, and they are well tolerated immunologically. Silicones prevent the formation of foam in equipment for artificial blood circulation (heart-lung machines). The surfaces of such equipment, and of the... 

The failure of silicone rubber in breast implants has received plenty of coverage in the popular press and several technical articles have been reviewed by Lewis (71). It appears that there have been a number of failure mechanisms but they all generally relate to lack of thorough testing to cover the expected lifetime and all service conditions. For cases of failed tissue expanders he suggests the causes were a combination of poor design and poor manufacturing. 

Silicones have been used in medical science for a variety of prosthetic applications because of their unique properties such as biocompatibiUty, weather resistance, low chemical reactivity, oxidation resistance and low toxicity. These properties make them suitable for a variety of applications, including maxillofacial reconstruction, breast implants, cochlear implants, artificial corneas and artificial skin. Silicone rubber (SR) implants have long been used for local contour corrections, such as nasal, chin, and cheek augmentation. In addition, arthritic knees and joints are effectively replaced by SR prostheses [1 ]. 

In 1962, Cronin and Gerow implanted silicone shells into dogs, which was a significant change in breast augmentation. The breast implant was crosslinked and reinforced silicone rubber shell that encapsulated a silicone gel or saline solution. The silicone gel comprised crosslinked silicone elastomer, mainly PDMS and a low molecular weight silicone fluid (also PDMS). There were many variations in the PDMS functionalities by different manufacturers to attain desired gel properties. Saline-filled implants were first manufactured as Simaplast in 1965 but did not have the same confluence due to the water-like viscosity of saline as compared to a more viscous gel. 

Vincenz Czerny reportedly performed the first augmentation mammoplasty in 1895 using a benign lipoma taken from patients hip. In the early and mid-20th century, many different materials were used for implantation or injection into the breast of patients including paraffin, petroleum jelly, ground rubber and silicone oils. Most of the prehminary... 

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