title: Surface detail reproduction under simulated pulpal pressure: a 3-dimensional optical profilometer and scanning electron microscopy evaluation.
abstract: BACKGROUND
  It is not clear whether more hydrophilic impression materials are better able to copy and transfer dentin surface detail than less hydrophilic ones.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the reproduction of dentin surface detail by means of hydrophobic and hydrophilic elastomeric impression materials under simulated pulpal pressure and their ability to transfer surface detail onto casts produced from such impressions.
  
  
  METHODS
  The wettability of the impression materials (n=8) was determined by contact angle measurement with an evolution period of 135 seconds. Dentin moisture was provided by means of pulpal pressure simulation, and objective analyses were performed by measuring the average roughness value (Ra) with a 3-D optical profilometer (n=10). One specimen from each group was analyzed with scanning electron microscopy. Contact-angle values were analyzed with a repeated measures ANOVA, and detail reproduction was tested with 3-way ANOVA (α=.05). The Bonferroni correction was used to control Type I error for follow-up analyses.
  
  
  RESULTS
  Contact angle measurements revealed significant differences depending on the impression material used and time of the measurement (P<.001). The Ra values of the hydrophilic impression materials, which were made from dry specimens, and the pulpal pressure simulated dentin surfaces did not differ from the dentin surfaces (P>.013). The hydrophobic impression material showed similar detail reproduction ability in a dry field, but loss of detail (evaluated subjectively) and increased roughness values (evaluated objectively) were recorded in a moisturized field (P=.004). Polyurethane-based cast material successfully reproduced the surface texture (P≥.006), whereas Type IV gypsum material was unable to reproduce this texture to the same extent.
  
  
  CONCLUSIONS
  The hydrophilic impression materials tested showed similar ability to reproduce detail under simulated pulpal pressure. Polyurethane-based cast material successfully reproduced the surface texture.
authors.affiliation: Department of Prosthetics, Faculty of Dentistry, Baskent University, Ankara, Turkey. zlemacr@gmail.com
authors.forename: Ozlem
authors.initials: O
authors.lastname: Acar
authors.forename: Selim
authors.initials: S
authors.lastname: Erkut
authors.forename: Manas
authors.initials: M
authors.lastname: Lakshmipathy
mesh_terms: D000704:Analysis of Variance; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D021621:Imaging, Three-Dimensional; D003765:Models, Dental; D012117:Resins, Synthetic / Q000737:chemistry; D012828:Silicones / Q000737:chemistry; D013499:Surface Properties; D017155:Wettability
chemical_list: D003760:Dental Impression Materials; C022821:Impregum; D012117:Resins, Synthetic; D012828:Silicones