title: An investigation of the rheological properties of 10 vinyl-polysiloxane impression materials.
abstract: OBJECTIVE
  The time required for 10 vinyl-polysiloxane impression materials to reach a viscosity of 5000 poise (Tcv) was estimated. This viscosity was selected based on previous work that suggested that an impression material might not be workable if its viscosity exceeded this limit. The effect of variations in the time of placement of the impression materials into a simulated oral-temperature environment was also studied.
  
  
  METHODS
  The change in the viscosity of the impression materials was recorded with a viscometer at oral temperature. Impression materials were placed at either 20 seconds, 30 seconds, or 40 seconds from the start of mixing.
  
  
  RESULTS
  There were statistically significant differences in Tcv among various impression materials. Variations in placement time significantly affected the Tcv of six impression materials.
  
  
  CONCLUSIONS
  Knowledge of the viscosity change of an impression material is beneficial in the clinical selection of an impression material.
authors.affiliation: Advanced Education Prosthodontics, Northwestern University Dental School, Chicago, Il.
authors.forename: J
authors.initials: J
authors.lastname: Chai
authors.forename: I C
authors.initials: IC
authors.lastname: Pang
authors.forename: D
authors.initials: D
authors.lastname: Leong
authors.forename: J E
authors.initials: JE
authors.lastname: Kim
authors.forename: P
authors.initials: P
authors.lastname: Torres
mesh_terms: D000704:Analysis of Variance; D003760:Dental Impression Materials / Q000737:chemistry*; D008422:Materials Testing; D011145:Polyvinyls / Q000737:chemistry*; D012212:Rheology; D012833:Siloxanes / Q000737:chemistry*; D014783:Viscosity
chemical_list: D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane