exhibit unique properties based on their chemical structure. The silicones
have the water-resistant hydrocarbon groups arrayed along the outside of
the chain of Si-O atoms. Cells do not attach themselves to the silicones.
Chemists could make high molecular weight polymers and low molecular weight
Silicones' water-resistant molecular surface
attachment and makes them seem inert.
Heat and Chemical Resistant
15. Breast Augmentation
This is about silicones
as breast augmentation implants.
as Hydrocephalic Shunts
GE first developed
practical silicones. Corning Glass - once cooperative with GE on
silicones - went its own direction with silicones. They went
into competition with General Electric. The giant glass company lacked
the chemical expertise to develop silicone polymers or to manfacture them
efficiently so they turned to Dow Chemicals for help. Dow and Corning
formed a partnership in 1943. This joint venture would be a separate company,
owned by Corning and Dow, called appropriately, Dow
||After World War
II and the Korean War, our nation experienced heady times. America
built structures like the interstate highway system. Scientists
and engineers and manufacturers had new materials for building blocks:
Carothers had invented nylon;. Speed
Marvel led the invention of synthetic rubber; Eugene Rochow invented
Implants as Hydrocephalic Shunts:
Dow Corning took their silicones
into a new field for synthetic materials--medicine. Medical scientists
were looking to the arsenal of materials that chemists were making
to improve medicine. After all, surgeons still used "catgut"
sutures, the processed intestinal walls of sheep or cows, to sew wounds
together. In many ways, the practice of medicine had not changed
Dow Corning scientists and
academic physicians and research scientists looked at silicone material
for medical applications. Silicone’s chemical and physical properties seemed
attractive for medical devices. Chemically, silicones seemed inert,
so they might not react with the chemicals in the body. Silicones' high
temperature stabiity suggested they might be easily sterilized should the
physicians wish to use them during surgery, or even implant them in the
came quickly. Dow Corning cooperated with Doctors F. E. Nulsen and
E. B. Spitz to develop the hydrocephalic
shunt, a silicone rubber tube placed into a child’s head to relieve
hydrocephalus, that is, "excess of cerebrospinal fluid in the cranial cavity
causing enlargement of the skull and resulting in mental retardation."
What was critically important
was that, in the more than 4,000 shunts implanted, the silicone worked
well. Surgeons had a look at a couple of implants after they
had been in the body for a long time. The silicone materials caused
no reaction in the tissue surrounding the implant.
Scientists note facts like
that. Silicone rubber's stability in the human body suggested that
the other forms of silicone products, particularly the rubbers, resins
and fluids, might be useful as medical devices that could be implanted.
Dow Corning offered silicone
materials to two plastic surgeons, Thomas Cronin and Frank Gerow of the
University of Texas who developed a silicone breast implant in about
1960. Their implant was developed for use by women who had
had breasts removed in the surgery called mastectomy. The new silicone
replaced sponges that had been used previously. The spongy implants
hardened and looked and felt less natural after a period of time.
The silicone rubber sac filled with silicone gel was called a mammary prosthesis.
Dow Corning marketed the Cronin implant in 1964, two years after the first
human trial implant. Thousands and thousands of women elected silicone
government's National Institutes of Health
(NIH) began implanting the whole series of new polymers in animals
to determine how living tissue behaves in the presence of these foreign
Their objective was clear:
If these synthetic materials could be tolerated in tissue, this might lead
to many new ways to use the materials in the body. The NIH studies
showed that a whole series of familiar synthetic materials, nylon, Teflon®,
Mylar®, polyester, silicone and polyethylene, could be implanted in
animals over a long period of time with minimal irritation or other
physical response. The excellent implant behavior of a number of
materials fueled the thinking that most synthetic polymers would be safe.
(You can check recent work
by NIH on implants by searching
the NIH website).
During the 1960's, Dow Corning
improved the tactile properties of their breast implant device. They
eliminated a seam and made the outer sac thinner. Other manufacturers
joined Dow Corning in the rapidly growing implant market. Dow Corning
made additional changes during the 1970's.
In 1977, a woman who claimed
her implants had ruptured, received a $170,000 settlement of a law suit
from Dow Corning. The U.S. Food and Drug Administration, which had been
quiet on the issue of implants, changed its policy and demanded more safety
information from implant device manufacturers. But the silicone breast
implants were not impacted by the FDA decision.