title: Comparative evaluation of physical properties of four tissue conditioners relined to modeling plastic material.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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<0.05.
  
  
  RESULTS
  Complex modulus and loss tangent values of TC were not significantly different among specimens containing 0, 2, 5 and 10 wt.%-SZ, respectively. In FT and TC containing 2 wt.%-SZ, these values were not significantly different between 1 and 28 days in both water- and saliva immersions.
  
  
  CONCLUSIONS
  The results suggest that relining with modeling plastics does affect TC's inherent dynamic viscoelastic properties, while the other tissue conditioners investigated may be found to have changed viscoelastic properties as a consequence of vicinity to the modeling plastics.
authors.affiliation: Associate Professor, Laser Research Center of Dentistry, Dentistry Research Institute, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Monzavi
authors.affiliation: Associate Professor, Dental Implant Research Center, Dentistry Research Institute, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hakimeh
authors.initials: H
authors.lastname: Siadat
authors.affiliation: Professor, Iran Polymer and Petrochemical Institute (IPPI), Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Atai
authors.affiliation: Associate Professor, Dental Research Center, Dentistry Research Institute, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Alikhasi
authors.affiliation: Resident of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Vahideh
authors.initials: V
authors.lastname: Nazari
authors.affiliation: Resident of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Sadigheh
authors.initials: S
authors.lastname: Sheikhzadeh
keywords: Elastic Modulus; Modeling Plastics; Tissue Conditioning, Dental