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a*i
发帖数: 1652 | 1 一直对这个感兴趣。前不久好像因材料毒性出了事，现在又弄好了。
懂行的说说。。。 | m*******o
发帖数: 4179 | 2 恩，还有，有没有一种材料让它之后看上去真假莫辨？
【在 a*i 的大作中提到】
: 一直对这个感兴趣。前不久好像因材料毒性出了事，现在又弄好了。
: 懂行的说说。。。
| s**********8
发帖数: 25265 | 3 没隆过。。
【在 a*i 的大作中提到】
: 一直对这个感兴趣。前不久好像因材料毒性出了事，现在又弄好了。
: 懂行的说说。。。
| s**********8
发帖数: 25265 | 4 看你激动的， 语无伦次了都
【在 m*******o 的大作中提到】
: 恩，还有，有没有一种材料让它之后看上去真假莫辨？
| a*i
发帖数: 1652 | 5 关键是手感了。硅胶还是挺有手感的。以前还有用生理盐水填充的。
无非是探索模量(硬度)，强度(拉伸)等参数。。。
【在 m*******o 的大作中提到】
: 恩，还有，有没有一种材料让它之后看上去真假莫辨？
| a*i
发帖数: 1652 | 6 http://www.tms.org/pubs/journals/jom/0909/pruitt-0909.html
Silicone has been utilized in breast implants since 1962; however, early
designs were prone to rupture and leaking.12 The first implants utilized low
viscosity forms of silicone gel encased in a solid silicone elastomer shell
but were prone to failure through tissue contracture around the implant or
rupture.12–14 Rupture of the implant shell enabled the silicone to leak
into the surrounding tissue, which could then elicit a chronic inflammatory
response. Over the next 20 years, second and third generations of breast
implants experimented with different silicone gels and encasement designs to
minimize or prevent leaks and inflammatory complications. While these
implants were a vast improvement over previous design iterations, leakage
and rupture were still major problems.
Many of the early designs and materials used were prior to the 1976 Medical
Device Act that provided the Federal Drug Administration (FDA) the authority
to review and regulate medical devices.4 Without any formal regulation,
companies could switch materials used in their devices without the need of
FDA approval. Thus, the earlier silicone breast implant designs were not
subjected by the FDA to the scrutiny of structural assessment and
biocompatibility testing that newer devices must undergo prior to approval
for clinical use. In the early 1990s, extensive litigation and research into
the realm of silicone breast implant safety ensued with great controversy.
The premise of these lawsuits was that leaking of silicone would lead to
connective tissue disease, immune reactions, and ultimately autoimmune
disorders.15
The FDA put together a scientific committee to assess the integrity and
medical concerns surrounding breast implants in 1991, while mandating the
withdrawal of silicone implants for cosmetic use until the investigation of
the scientific committee was complete.14 In 1999, the scientific committee
concluded that silicone breast implants were not responsible for the
immunological diseases that had been rampant in many patients who had the
silicone implants.15 In 2006, the FDA approved the re-release of silicone
breast implants utilizing a crosslinked form of the polymer, under the
conditions that patients must be at least 22 years of age and would require
an MRI in the first 3 years and then every 2 years thereafter. The current
view is that these implants will not likely last a “lifetime” as initially
promised in the early release of silicone implants, and women should plan
to have multiple surgeries.16
Modern silicone breast implants have evolved in design to ensure safety
against rupture and leakage. The primary mechanical design requirement of a
breast implant is resistance to rupture. This is typically modeled as a thin
-walled pressure-vessel to address the stress resulting from peak
compressive forces. The primary design change from the first implants has
been in the utilization of a crosslinked form of silicone that does not leak
if the surrounding shell is ruptured or torn. Figure 6 shows the design
evolution of silicone implants and provides an image showing the
consequences of rupture when the silicone has low viscosity. In the modern
silicone implant the implant retains its structural integrity and does not
leak into adjacent tissue.
However, several concerns linger in the wake of the recent FDA approval of
silicone implants. One concern is founded upon prior clinical complications
of leaking and association with autoimmune disease. While scientific studies
have shown no link between silicone and autoimmune disease, much of the
public at large remains cautious. Also, while a large number of clinical
studies have been undertaken to demonstrate the safety of silicone implants,
the long-term performance of these implants has not been established.
This is an example of a design iteration process where the clinical
performance has driven the research for optimization of materials selection
and design of the implant to ensure safety. As with all devices, the
clinical performance drives a continuous feedback loop, and it will be years
before the long-term performance of crosslinked silicone breast implants is
understood. |
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