Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 6 2013 12 15 506 15 Abbas Monzavi Associate Professor, Laser Research Center of Dentistry, Dentistry Research Institute, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran. Hakimeh Siadat Associate Professor, Dental Implant Research Center, Dentistry Research Institute, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Atai Professor, Iran Polymer and Petrochemical Institute (IPPI), Tehran, Iran. Marzieh Alikhasi Associate Professor, Dental Research Center, Dentistry Research Institute, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran. Vahideh Nazari Resident of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran. Sadigheh Sheikhzadeh Resident of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 16 Little is known about the interaction of tissue conditioners and modeling plastics. This study evaluates the influence of a variety of commercial tissue conditioners on alteration of viscoelastic properties of modeling plastics.In this in vitro study, the dynamic viscoelastic properties of four commercially available tissue conditioners (TC), Visco-gel (VG), GC Soft-Liner (SL), FITT (FT), and Coe Comfort (CC), relined to modeling plastics with a thickness of 2mm were evaluated after 1 and 7 days of water immersion with the use of storage modulus, loss modulus, and tan delta parameters. Values for these three parameters for each tissue conditioner were statistically analyzed by Kruskal Wallis and Mann Whitney tests with P value sets at https://fid.tums.ac.ir/index.php/fid/article/view/591 https://fid.tums.ac.ir/index.php/fid/article/download/591/566