The sterilization of impressions with quimioclave, ultraviolet rays, hypochlorite, iodine compounds, chlorhexidine solutions and autoclave (Johansen & Stackhouse 1987) were considered costly, time consuming and could change dimensionally impressions. As a practical alternative disinfection took place (Lagenwalter et al. 1990). Studies on dimensional changes caused by disinfectants concluded that immersion within 60 minutes of addition silicones in sodium hypochlorite 10,000 ppm was the safest method, (Minagi et al. 1986) and that after immersion in a solution of 2% glutaraldehyde for 10 hours, showed high stability. (Johansen & Stackhouse 1987) Several authors (Bergman 1989, Langenwalter et al. 1990, Matyas et al. 1990, Tullner et al. 1988) reported dimensional changes in polivynilsiloxanes after disinfection, although clinically insignificant. Pratten et al. (1990) demonstrated changes in wettability caused by disinfectants in hydrophilic silicones. Martin et al. (2007) reported the lack of consensus protocols and the presence of unknown substances in silicones, leading to different behaviors in contact with disinfectants. Different authors, (Bock et al. 2008, Kotsiomiti et al. 2008, Melilli et al. 2008) concluded that chemical disinfection produces dimensional changes that do not influence the clinical outcome.