title: Linear dimensional accuracy of a polyvinyl siloxane of varying viscosities using different impression techniques.
abstract: OBJECTIVE
  The present study is an in vitro study to evaluate the linear dimensional accuracy of commercially available polyvinyl siloxanes of varying viscosities using different impression techniques.
  
  
  METHODS
  Different impression techniques used were: (a) putty wash, with a two-step technique with polyethylene spacer, using a stock tray; (b) putty wash, with a one-step technique, using a stock tray; (c) single-mix technique, utilizing medium viscosity in a custom tray; and (d) multiple-mix technique, utilizing a heavy- and low-viscosity combination in a custom tray. For each technique, 10 impressions were made of a metallic maxillary dentulous master model.
  
  
  RESULTS
  The result of this study dictates that a heavy- and low-viscosity combination, double-mix technique in a custom tray produced an accurate result in all dimensions, followed by the single-mix technique, utilizing medium viscosity in a custom tray, and the putty wash two-step technique with polyethylene spacer, using a stock tray. Group 2 putty wash, one-step, simultaneous technique produced the least accurate result in all dimensions.
  
  
  CONCLUSIONS
  The putty wash two-step techniques were found to be as accurate as the multiple-mix technique, utilizing a heavy- and low-viscosity combination in a custom tray, and the single-mix technique, utilizing medium viscosity in a custom tray. Making custom trays is time consuming and costly.
authors.affiliation: Department of Maxillofacial Prosthodontics and Implantology, Dental College Azamgarh, Azamgarh, Uttar Pradesh, India.
authors.forename: Sunil
authors.initials: S
authors.lastname: Mishra
authors.forename: Ramesh
authors.initials: R
authors.lastname: Chowdhary
mesh_terms: D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000145:classification / Q000295:instrumentation; D003890:Desiccation; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D003765:Models, Dental; D020959:Polyethylene / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014783:Viscosity
chemical_list: D003760:Dental Impression Materials; D011145:Polyvinyls; D012828:Silicones; D012833:Siloxanes; C034183:vinyl polysiloxane; D020959:Polyethylene
keywords: custom tray; dimensional accuracy; impression; polyvinyl siloxane; stock tray