title: Pre- and post-set hydrophilicity of elastomeric impression materials.
abstract: OBJECTIVE
  To evaluate the hydrophilicity of one polyether, four poly(vinyl siloxanes), and one condensation silicone before and after setting under simulated clinical conditions, and to correlate the findings to the contact angle values of these materials.
  
  
  METHODS
  The hydrophilicity before and after setting, as well as the contact angle values of the elastomeric impression materials were evaluated. Part I: A freshly extracted tooth, which was prepared for a full coverage restoration, was kept in saliva for 15 minutes and was then rinsed for 10 seconds. Impressions were taken without any drying of the tooth. A total of ten samples were taken for each material. The specimens were evaluated at a 10x magnification for defects. Part II: After the evaluation, the impressions were poured with a type IV dental stone and were left for 1 hour before separation. The stone specimens were then evaluated at a 10x magnification for negative voids. A total of 60 specimens were tested. Part III: Sixty identical 10 x 10 x 4 mm(2) plastic molds were used for the fabrication of the impression material specimens. Contact angle measurements of each specimen were made 1 hour after separation from the plastic mold. A calibrated pipette was used to place a drop (0.05 ml) of saturated calcium sulfate dehydrate onto each specimen. Digital images were taken for each specimen, and contact angle values were measured with appropriate software.
  
  
  RESULTS
  Part I: One-way ANOVA revealed significant differences among the materials (F = 15.526, p < 0.0005). Polyether had the fewest voids. The poly(vinyl siloxanes) did not present any significant differences among them, according to Tukey's HSD test (p < 0.05). Part II: One-way ANOVA revealed significant differences among the materials (F = 46.164, p < 0.0005). Polyether (Impregum) was the material which produced stone specimens with the fewest voids. Part III: One-way ANOVA indicated significant differences among the elastomeric impression materials (F = 494.918, p < 0.0005). Polyether displayed the smallest contact angle values.
  
  
  CONCLUSIONS
  Polyether was the most hydrophilic of all materials tested.
authors.affiliation: Division of Graduate and Postgraduate Prosthodontics, Tufts University, School of Dental Medicine, Boston, MA, USA. kmichalakis@the.forthnet.gr
authors.forename: Konstantinos X
authors.initials: KX
authors.lastname: Michalakis
authors.forename: Athina
authors.initials: A
authors.lastname: Bakopoulou
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirayama
authors.forename: Dimitris P
authors.initials: DP
authors.lastname: Garefis
authors.forename: Pavlos D
authors.initials: PD
authors.lastname: Garefis
mesh_terms: D002133:Calcium Sulfate / Q000737:chemistry; D003734:Dental Casting Investment / Q000737:chemistry; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D020724:Elastomers / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008422:Materials Testing; D010969:Plastics / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D012463:Saliva / Q000502:physiology; D012826:Silicone Elastomers / Q000737:chemistry; D012828:Silicones; D012833:Siloxanes / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D017155:Wettability
chemical_list: D003734:Dental Casting Investment; D003760:Dental Impression Materials; D004129:Dimethylpolysiloxanes; D020724:Elastomers; D004987:Ethers; C022821:Impregum; C020964:MDX 4-4210; D010969:Plastics; D011145:Polyvinyls; D012117:Resins, Synthetic; D012826:Silicone Elastomers; D012828:Silicones; D012833:Siloxanes; C480691:aquasil; C118335:president, silicone impression material; C034183:vinyl polysiloxane; D014867:Water; D002133:Calcium Sulfate