title: Type IV gypsum compatibility with five addition-reaction silicone impression materials.
abstract: BACKGROUND
  The compatibility of current addition-reaction silicone impression materials and Type IV gypsum products is not completely understood.
  
  
  OBJECTIVE
  The purpose of this study was to compare surface detail reproduction between various combinations of contemporary addition-reaction silicone impression materials and Type IV gypsum products.
  
  
  METHODS
  Under standardized conditions, 300 impressions were made of a ruled stainless steel die (ADA specification 19), using 5 addition-reaction silicones (Examix-NDS, Doric-ES Flo-Light, Panasil Contact Plus, Extrude Wash, and President Plus Jet). Fifteen impressions of each material were poured with each Type IV gypsum product (Silky-Rock, Fuji Rock, Suprastone, or Vel-Mix). Using x12 magnification, 2 independent examiners scored the reproducibility of a 20-microm line in both the impression and the resultant casts. Statistical analysis was performed using 2-way analysis of variance and post hoc Bonferroni testing (alpha = .05).
  
  
  RESULTS
  All impression materials tested fully reproduced the 20-microm line. Different impression materials showed different compatibility with different Type IV gypsum products. Only 25% of the Type IV gypsum casts completely reproduced the resultant 20-microm line with fine margins, and 88% of the completely reproduced casts were made from Suprastone.
  
  
  CONCLUSIONS
  Not all combinations of impression material and Type IV gypsum products used exhibited similar compatibility.
authors.affiliation: Department of Conservative Dentistry, Eastman Dental Institute, University of College London, England.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Butta
authors.forename: Christopher Jeremy
authors.initials: CJ
authors.lastname: Tredwin
authors.forename: Michael
authors.initials: M
authors.lastname: Nesbit
authors.forename: David R
authors.initials: DR
authors.lastname: Moles
mesh_terms: D000704:Analysis of Variance; D002133:Calcium Sulfate / Q000737:chemistry*; D003760:Dental Impression Materials / Q000737:chemistry*; D008422:Materials Testing; D015203:Reproducibility of Results; D012826:Silicone Elastomers / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry
chemical_list: D003760:Dental Impression Materials; D012826:Silicone Elastomers; D012833:Siloxanes; D002133:Calcium Sulfate