title: The effect of surface moisture on detail reproduction of elastomeric impressions.
abstract: BACKGROUND
  Monophase and dual-viscosity impression techniques are available with little knowledge of which one might render better quality under wet and dry surface conditions.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether type of material, viscosity selection, and presence of moisture affect detail reproduction of elastomeric impressions.
  
  
  METHODS
  Single-viscosity systems were polyether (Impregum Penta) and vinyl polysiloxanes (President MonoBody, Extrude MPV, and Aquasil). Dual-viscosity systems included polyether (Impregum Penta/Permadyne Garant) and vinyl polysiloxanes (Dimension Penta H/Dimension Garant L, Extrude Extra/Extrude Wash, and Aquasil/Aquasil LV). Impressions were made of a surface analyzer calibration standard possessing a uniform "saw-tooth" pattern with a mean roughness (Ra) of 2.87 mum, which was one fourth of the peak-to-valley height. Each of the 8 impression groups was subjected to dry (control) and wet conditions. The wet condition consisted of 3 mL of distilled water applied to the surface of the standard but allowed to escape during the procedure. Eighty impressions were made, 5 for each test group. After setting, the surface of each impression was scanned at 5 locations using a Surfanalyzer 4000. A 3-factor ANOVA and Student-Newman-Kuels test were used to analyze the data (alpha=.05).
  
  
  RESULTS
  There were significant differences between polyether and vinyl polysiloxane materials, dual and monophase techniques, and the 2 surface conditions (P<.05). Cross-product interactions were not significant, allowing comparison of mean values for each factor. The mean Ra for single viscosity was 2.21 mum versus 1.67 mum for dual viscosity; polyether was 2.12 mum versus 1.89 mum for addition silicone; and under dry conditions, the mean was 2.04 mum versus 1.86 mum for wet conditions.
  
  
  CONCLUSIONS
  Single-viscosity systems reproduced the standard saw-tooth pattern better than the dual-viscosity systems, as did polyether impression materials compared to addition silicones. Moisture led to a lower Ra or less detail compared to dry conditions.
authors.affiliation: Department of Restorative Dentistry, Box 357456, University of Washington, Seattle, WA 98195-7456, USA. gjohnson@u.washington.edu
authors.forename: Glen H
authors.initials: GH
authors.lastname: Johnson
authors.forename: Xavier
authors.initials: X
authors.lastname: Lepe
authors.forename: Tar Chee
authors.initials: TC
authors.lastname: Aw
mesh_terms: D000704:Analysis of Variance; D003760:Dental Impression Materials / Q000737:chemistry*; D020724:Elastomers / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011145:Polyvinyls / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D012826:Silicone Elastomers / Q000737:chemistry; D012828:Silicones; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D003760:Dental Impression Materials; D020724:Elastomers; D004987:Ethers; C102652:Extrude; C022821:Impregum; C096535:Permadyne Premier; D011145:Polyvinyls; D012117:Resins, Synthetic; D012826:Silicone Elastomers; D012828:Silicones; D012833:Siloxanes; C480691:aquasil; C118335:president, silicone impression material; C034183:vinyl polysiloxane; D014867:Water