Group 2 (Filippini JL, Floumanhaft MJ, Fluger KR, Fuller AD, Gilbert MK, Gliwa CL): What is the effect of disinfection materials on PVS and polyether Impression materials? Poly(vinylsiloxane) (PVS), also known as addition silicone, has the greatest dimensional stability of all impression materials, but it is hydrophobic. Some PVS formulations that contain surfactants to give them hydrophilic properties will result in improved wettability, causing them to expand upon contact with moisture. Polyether (PE) has the second best dimensional stability among all impression materials and is inherently hydrophilic.6 In a 1988 article, Johnson et al cautioned that PE is particularly sensitive to immersion disinfection.4 More studies recent studies carried out by Adabo et al. . (1999) and Melilli et al. (2008) indicate that PVS and PE have inherently different reproduction accuracy and that dimensional differences caused by immersion disinfection procedures are not clinically relevant.1,5 In a review of current impression materials, notably Aquasil Ultra Monophase® and Impregum Penta...