title: The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study.
abstract: OBJECTIVE
  To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique.
  
  
  METHODS
  A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint(™) II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector.
  
  
  METHODS
  The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student's Newman-Keul's test.
  
  
  RESULTS
  When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint(™) II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint(™) II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint(™) II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively.
  
  
  CONCLUSIONS
  Among the impression materials Imprint(™) II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results.
authors.affiliation: Department of Prosthodontics, College of Dental Sciences, Davangere, Karnataka, India.
authors.forename: Nirmala
authors.initials: N
authors.lastname: Kumari
authors.affiliation: Department of Prosthodontics, Bapuji Dental College and Hospital, Davangere, Karnataka, India.
authors.forename: D B
authors.initials: DB
authors.lastname: Nandeeshwar
keywords: Dimensional accuracy; double mix impression technique; impression materials; polyvinyl siloxane; single mix impression technique