title: Accuracy of 3 conceptually different die systems used for implant casts.
abstract: BACKGROUND
  Given that meticulous implant prosthodontic procedures are recommended to obtain the best possible intraoral fit, the die systems used for multi-implant casts warrant further investigation. PURPOSE. The purpose of this in vitro study was to compare the accuracy of implant casts fabricated from 3 conceptually different die systems at the solid, sectioned, and repeated stages.
  
  
  METHODS
  Thirty direct transfer implant impressions were made of the master cast with a polyether impression material. Ten experimental implant casts were fabricated for each of the 3 different die systems tested: double-pour (Pindex), plastic base (DVA), and die tray (KO Tray). The solid experimental casts were sectioned and then removed from the die system 30 times. Linear distances between steel balls placed on each abutment replica were measured with a traveling microscope to determine the accuracy of the experimental casts at different stages. Data were analyzed with repeated-measures analysis of variance (alpha=.05) and the post hoc Ryan-Einot-Gabriel-Welsch multiple-range test (REGWQ).
  
  
  RESULTS
  Repeated-measures analysis of variance revealed a significant interaction between the die systems and different stages (P=.0432). REGWQ showed the die tray system to be significantly more accurate at the solid than at the sectioned and repeated stages. The die tray system was significantly less accurate than the double-pour and plastic base systems at the sectioned stage.
  
  
  CONCLUSIONS
  Within the limitations of this study, the use of a double-pour or plastic base die system is recommended when sectioned dies are needed for a multi-implant-retained prosthesis.
authors.affiliation: Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, The Ohio State University, Columbus, Ohio, 43210-9422, USA. Wee.12@osu.edu
authors.forename: Alvin G
authors.initials: AG
authors.lastname: Wee
authors.forename: Ansgar C
authors.initials: AC
authors.lastname: Cheng
authors.forename: Ryan N
authors.initials: RN
authors.lastname: Eskridge
mesh_terms: D000180:Acrylic Resins; D000704:Analysis of Variance; D016001:Confidence Intervals; D000044:Dental Abutments; D003735:Dental Casting Technique / Q000295:instrumentation; D015921:Dental Implants; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D017267:Dental Prosthesis Design; D006801:Humans; D008853:Microscopy; D003765:Models, Dental; D010969:Plastics; D012117:Resins, Synthetic; D013223:Statistics as Topic; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D015921:Dental Implants; D003760:Dental Impression Materials; C022821:Impregum; D010969:Plastics; D012117:Resins, Synthetic; C060386:Triad resin