title: Accuracy of Implant Position Transfer and Surface Detail Reproduction with Different Impression Materials and Techniques.
abstract: OBJECTIVE
  The purpose of this study was to compare the accuracy of implant position transfer and surface detail reproduction using two impression techniques and materials.
  
  
  METHODS
  A metal model with two implants and three grooves of 0.25, 0.50 and 0.75 mm in depth on the flat superior surface of a die was fabricated. Ten regular-body polyether (PE) and 10 regular-body polyvinyl siloxane (PVS) impressions with square and conical transfer copings using open tray and closed tray techniques were made for each group. Impressions were poured with type IV stone, and linear and angular displacements of the replica heads were evaluated using a coordinate measuring machine (CMM). Also, accurate reproduction of the grooves was evaluated by a video measuring machine (VMM). These measurements were compared with the measurements calculated on the reference model that served as control, and the data were analyzed with two-way ANOVA and t-test at P= 0.05.
  
  
  RESULTS
  There was less linear displacement for PVS and less angular displacement for PE in closed-tray technique, and less linear displacement for PE in open tray technique (P<0.001). Also, the open tray technique showed less angular displacement with the use of PVS impression material. Detail reproduction accuracy was the same in all the groups (P>0.05).
  
  
  CONCLUSIONS
  The open tray technique was more accurate using PE, and also both closed tray and open tray techniques had acceptable results with the use of PVS. The choice of impression material and technique made no significant difference in surface detail reproduction.
authors.affiliation: Associate Professor, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Alikhasi
authors.affiliation: Professor, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences and Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hakimeh
authors.initials: H
authors.lastname: Siadat
authors.affiliation: Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Elaheh
authors.initials: E
authors.lastname: Beyabanaki
authors.affiliation: Statistics Consultant, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Javad
authors.initials: MJ
authors.lastname: Kharazifard
keywords: Dental Implants; Dental Impression Materials; Dental Impression Technique