PURPOSE:To assess the capsules formed by silicone implants coated with polyurethane foam and with a textured surface. METHODS:Sixty-four Wistar albinus rats were divided into two groups of 32 each using polyurethane foam and textured surface. The capsules around the implants were analyzed for 30, 50, 70 and 90 days. Were analyzed the following parameters: foreign body reaction, granulation tissue, presence of myofibroblasts, neoangiogenesis, presence of synovial metaplasia, capsular thickness, total area and collagen percentage of type I and III, in capsules formed around silicone implants in both groups. RESULTS:The foreign body reaction was only present in the four polyurethane subgroups. The formation of granulation tissue and the presence of myofibroblasts were higher in the four polyurethane subgroups. Regarding to neoangiogenesis and synovial metaplasia, there was no statistical difference between the groups. Polyurethane group presented (all subgroups) a greater capsule thickness, a smaller total area and collagen percentage of type I and a higher percentage area of type III, with statistical difference. CONCLUSION:The use of polyurethane-coated implants should be stimulated by the long-term results in a more stable capsule and a lower incidence of capsular contracture, despite developing a more intense and delayed inflammatory reaction in relation to implants with textured surface.

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Background In the biological response to biomaterials, implant shell play a key role in immune and inflammatory reactions. Our hypothesis is that the capsules formed around nanotextured implants exhibit an immunohistochemical behavior different from those formed around polyurethane implants. Objectives Evaluate through immunohistochemistry markers the capsules formed around nanotextured and polyurethane implants. Methods Sixty albino female Wistar rats were divided into two groups (nanotextured and polyurethane), with 30 animals in each group. A mini silicone implant was inserted on the back of the animals. After the determined period, the animals were euthanized, and the capsules formed around the implants were studied. The capsules in the 30-, 60- and 90-day subgroups were analyzed via immunohistochemistry to detect α-SMA, TGF-β, CD34 and CD68 markers, via picrosirius staining to determine the density of type I and III collagen fibers and via hematoxylin and eosin staining to assess capsule thickness. A Wilcoxon-Mann-Whitney test was used to compare the groups, and a Kruskal-Wallis test was used to compare the subgroups. Results Lower α-SMA, TGF-β, CD34 and CD68 immunoexpression was observed in the nanotextured 30- and 60-day subgroups than in the corresponding polyurethane subgroups. In the 90-day subgroup, more pronounced α-SMA and CD34 immunoexpression was observed in the nanotextured group; however, TGF-β and CD68 immunoexpression remained lower. The nanotextured implants had reduced capsular thickness and greater formation of type I collagen in all the analyzed subgroups. Conclusions Nanotextured implants led to reduced immune and inflammatory reactions compared with polyurethane implants according to all analyzed variables.

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