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Simaplast, Klein-type, implants were fragile and had a 76% prevalence of leakage or deflation (Williams, 1972). Early HTV (high-temperature vulcanized) models from a number of manufacturers frequently deflated (Mladick, 1993). The Jenny, Heyer-Schulte models had a reported thickness of at least 0.016 inch, or 0.40 mm, that made them sturdy (Jenny, 1994; Schmidt, 1980). Modern RTV (room temperature vulcanized) models are reported to deflate infrequently (Gutowski et al., 1997; Mladick, 1993; and see discussion in Peters, 1997).

The high prevalence of shell rupture in one gel implant was said to reflect the unique process of dipping the gel into elastomer rather than filling a preformed elastomer rubber casing used with this particular model (MemeME, Aesthetech). Later models were said to correct this problem (MemeMP) and were certainly no longer made in this way (Middleton, 1998b; Middleton and McNamara, 1995). Early Ashley-type polyurethane-coated prostheses were also prone to rupture along the seam until this was modified (Cohney and Mitchell, 1997). Prevalence of rupture differing by brand of implant has been reported by Feng (IOM Scientific Workshop, 1998), and Peters and Francel have reported major differences in rupture for silicone gel implants of different vintages, up to 95% at 12 years' implantation with thin shelled, 1972-mid 1980s-implants (Francel et al., 1998; Peters et al., 1996). Others have also reported frequent rupture for these thinner-shelled implants, although the numbers could also reflect the effects of wear on long-duration implants and the biases inherent in patient groups that are identified because they present with problems that lead to explantation (De Camara et al., 1993; Harris et al., 1993; Malata et al., 1994a; Rolland et al., 1989a).

Separate descriptions of women with saline and gel implants in patient populations with systemic signs and symptoms (Cuéllar et al., 1995a; Dobke et al., 1995) might direct further inquiry, although some report similar autoantibodies in both saline and gel implant patients and atypical disease symptoms in saline implant patients (Byron et al., 1984; Martin et al., 1993; Miller et al., 1998; Vargas, 1979). Calcification has been associated with a particular make of implant, although it can occur around any implant (Peters et al., 1998; Rolland et al., 1989b). Implant rupture after closed compression capsulotomies is reported to depend on implant vintage (Lemperle and Exner, 1993). Other examples could be cited, but it is clear that complications such as capsular contracture, rupture, and silicone migration may vary with implants from different manufacturers based on factors that are not precisely identified, including different shells, different gel consistency and diffusion characteristics, different gel chemical composition and siloxane molecular weights, different shapes, and so forth (Ksander and Vistnes, 1985).