title: Effects of implant system, impression technique, and impression material on accuracy of the working cast.
abstract: OBJECTIVE
  This in vitro study aimed to identify the effects of the implant system, impression technique, and impression material on the transfer accuracy of implant impressions. The null hypothesis tested was that, in vitro and within the parameters of the experiment, the spatial relationship of a working cast to the placement of implants is not related to (1) the implant system, (2) the impression technique, or (3) the impression material.
  
  
  METHODS
  A steel maxilla was used as a reference model. Six implants of two different implant systems (Standard Plus, Straumann; Semados, Bego) were fixed in the reference model. The target variables were: three-dimensional (3D) shift in all directions, implant axis direction, and rotation. The target variables were assessed using a 3D coordinate measuring machine, and the respective deviations of the plaster models from the nominal values of the reference model were calculated. Two different impression techniques (reposition/pickup) and four impression materials (Aquasil Ultra, Flexitime, Impregum Penta, P2 Magnum 360) were investigated. In all, 80 implant impressions for each implant system were taken. Statistical analysis was performed using multivariate analysis of variance.
  
  
  RESULTS
  The implant system significantly influenced the transfer accuracy for most spatial dimensions, including the overall 3D shift and implant axis direction. There was no significant difference between the two implant systems with regard to rotation. Multivariate analysis of variance showed a significant effect on transfer accuracy only for the implant system.
  
  
  CONCLUSIONS
  Within the limits of the present study, it can be concluded that the transfer accuracy of the intraoral implant position on the working cast is far more dependent on the implant system than on the selection of a specific impression technique or material.
authors.affiliation: Justus-Liebig-University, Dental Clinic, Department of Prosthodontics, Giessen, Germany. Kerstin.Wegner@dentist.med.uni-giessen.de
authors.forename: Kerstin
authors.initials: K
authors.lastname: Wegner
authors.forename: Katharina
authors.initials: K
authors.lastname: Weskott
authors.forename: Martha
authors.initials: M
authors.lastname: Zenginel
authors.forename: Peter
authors.initials: P
authors.lastname: Rehmann
authors.forename: Bernd
authors.initials: B
authors.lastname: Wöstmann
mesh_terms: D015921:Dental Implants; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D006801:Humans; D066298:In Vitro Techniques; D008437:Maxilla; D003765:Models, Dental; D011145:Polyvinyls; D012833:Siloxanes
chemical_list: D015921:Dental Implants; D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane