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Biomaterials in Tissue Engineering
Published in Rajesh K. Kesharwani, Raj K. Keservani, Anil K. Sharma, Tissue Engineering, 2022
Blessing Atim Aderibigbe, Shesan John Owonubi
Polymers have also been designed for breast implants. Polymeric fillers synthesized from acrylamide by redox polymerization are biocompatible and are permanent injectable filler material for breast reconstruction (Kim et al., 2018). Polymers are also alternative to the use of acellular dermal matrices and are used as temporary reinforcement in patients undergoing breast reconstruction (Becker and Lind, 2013). An arborescent block copolymer prepared and investigated as breast implant did not exhibit leakage that can provoke inflammatory responses in patients (Becker and Lind, 2013). It is biocompatible when compared to silicone in the long term (Becker and Lind, 2013). Silicone gel-filled breast implants with a silicone outer shell are filled with silicone gel. They are approved by FDA for breast augmentation and reconstruction in women age 22 years or older. However, complications associated with silicone breast implants are capsular contracture, implant rupture, wrinkling, asymmetry, scarring, pain, infection, and anaplastic large cell lymphoma (Fda, 2017). A branched arborescent polyisobutylene core was reported to be an alternative biomaterial to silicone rubber. Implantation in a rabbit model revealed that the material exhibited excellent tissue–material interactions resulting from the lower surface energy of polyisobutylene that forms a thin layer on the surface of the material. No acute inflammation was observed and the material was highly biostable (Teck Lim et al., 2013).
New Elastomers: Biomacromolecular Engineering via Carbocationic Polymerization
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Silicone breast implants were introduced in 1963;53 their history has been reviewed.17,18,52 A breast implant consists of a rubbery shell, and a filler material—silicone gel or saline solution. The shell can be prefilled and sealed before it is inserted into the body, or can be filled after insertion via a valve. The shell is expected to provide strength and barrier properties, whereas the filling supplies bulk and consistency. The first-generation silicone gel implants (1960s–1970s) had the thickest shells and the most viscous gel. They felt too firm compared with natural breast tissue, so the layer thickness and gel viscosity were reduced in the second generation (early 1980s). This led to gel bleed and rupture of the shell. The third-generation implants consist of shells of intermediate thickness filled with gels of medium viscosity.17,18 Cohesive gel implants introduced recently are considerably firmer, and perceived to be harder than the natural breast tissue (Figure 7.3). The shape of the implant can be round, or “anatomically correct,” and the surface can be smooth or textured.
Selecting the Right Polymer for Biomaterial Applications
Published in Ijeoma F. Uchegbu, Andreas G. Schätzlein, Polymers in Drug Delivery, 2006
The hardness and toughness of lightly crosslinked PDMS (Silicone Rubber) may be enhanced by increasing the cross-link density (increasing the number of cross-links per unit volume). Silicone chains are crosslinked by replacing some of the –Si-CH3 groups with -Si-H and -Si-CH=CH2 groups, and adding platinum, which catalyses the addition of the two, forming -Si-CH2-CH2-Si- crosslinks between different chains. (5) Other ways to stiffen and toughen Silicone Rubber besides increasing the crosslink density, include increasing the silica filler content and/or substituting –Si-CH3 groups with Si-phenyl groups. The ability to “molecularly engineer” its mechanical properties, plus its inertness in biologic media, make PDMS eminently suitable as a substitute for stiffer tissues such as the ear, nose, and chin. Its use as a breast implant has been controversial [9,10]. The most attractive and successful breast implant was composed of a silicone rubber bag or capsule filled with a gel-like silicone polymer. It had the right “feel” of the tissue it was replacing, and was widely successful. Only a small percent of implants had to be removed, for a variety of reasons. It should be noted that finite failure rates are to be expected with all man-made devices, even implants. However, on the basis of a relatively few failures of the silicone gel-encapsulated silicone breast implants, lawyers filed class action liability suits claiming that patients were not properly informed about many potential undesirable effects before implantation. One claim made was that the outer surface of the PDMS capsule was supposed to have caused immune responses, leading to formation of antibodies to PDMS, but this claim was never demonstrated scientifically. In those rare cases when the silicone gel leaked out of the capsule, the plaintiffs claimed that it caused a variety of problems, including diseases ranging from lupus to lymphatic tumors [10]. Most of these claims have not been found to be statistically significant by scientific studies, but nevertheless some are still possible in a large patient population. However, the large awards handed down to plaintiffs by some judges have caused changes in the currently available implants, which now use a saline solution inside the PDMS capsule instead of a silicone gel. Silicone remains the material of choice for the outer capsule used for breast implants. A variety of outer capsule modifications have also been developed, such as incorporation of perfluorinated components in the PDMS composition, to reduce the permeability of the capsule wall to lower MW components in the silicone gel, and surface roughening to promote formation of a thin fibrous collagen capsule around the implant.
A prototype 3D modelling and visualisation pipeline for improved decision-making in breast reconstruction surgery
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2022
Sara Amini, Marta Kersten-Oertel
In 2020, more than 2 million new patients were diagnosed with breast cancer, making it the most common type of cancer in women (Sung, et al., 2021). Treatment options for breast cancer include: chemotherapy, radiotherapy, breast-conserving surgery and mastectomy. Mastectomy surgery, i.e. removal of breast tissue, is suggested for women who have a family history of breast cancer to avoid cancer (i.e. prophylactic mastectomy), patients who have recurrent cancer in the same breast, or in instances where breast-conserving surgery is not a possibility (DeSantis, et al., 2019). According to the National Cancer Database (NCDB, 2021), in 2018 more than 100,000 patients had a total mastectomy in the US alone. Many of these patients choose to have breast reconstruction surgery using an implant to restore the breast’s lost shape and volume. A breast implant is a silicone pocket filled with silicone gel or saline. There are a variety of implants available in different sizes and shapes, and typically the surgeon and the patient will agree on an implant to be used in a pre-surgery decision-making process.