title: Accuracy of a new ring-opening metathesis elastomeric dental impression material with spray and immersion disinfection.
abstract: BACKGROUND
  A new elastomeric impression material has been formulated with a ring-opening metathesis chemistry. In addition to other properties of clinical significance, the impression accuracy must be confirmed.
  
  
  OBJECTIVE
  The purpose of this study was to compare the accuracy of the new elastomeric impression material with vinyl polysiloxane and polyether following both spray and immersion disinfection.
  
  
  METHODS
  Impressions of a modified dentoform with a stainless steel crown preparation in the lower right quadrant were made, and type IV gypsum working casts and dies were formed. Anteroposterior (AP), cross-arch (CA), buccolingual (BL), mesiodistal (MD), occlusogingivobuccal (OGB), and occlusogingivolingual (OGL) dimensions were measured using a microscope. Working cast and die dimensions were compared to those of the master model. The impression materials were a newly formulated, ring-opening metathesis-polymerization impression material (ROMP Cartridge Tray and ROMP Volume Wash), vinyl polysiloxane (VPS, Aquasil Ultra Monophase/LV), and a polyether (PE, Impregum Penta Soft/Permadyne Garant L). Fifteen impressions with each material were made, of which 5 were disinfected by spray for 10 minutes (CaviCide), 5 were disinfected by immersion for 90 minutes (ProCide D), and 5 were not disinfected. There were significant cross-product interactions with a 2-way ANOVA, so a 1-way ANOVA and Dunnett's T3 multiple comparison test were used to compare the dimensional changes of the 3 impression materials, by disinfection status and for each location (alpha=.05).
  
  
  RESULTS
  For ROMP, there were no significant differences from the master, for any dimension, when comparing the control and 2 disinfectant conditions. No significant differences were detected among the 3 impression materials for CA, BL, and MD. The working die dimensions of OGB and OGL for VPS with immersion disinfection were significantly shorter than with PE and ROMP (P<.05). Overall, the AP dimension was more accurate than CA, and the BL of working dies was 0.040 mm greater in diameter than MD.
  
  
  CONCLUSIONS
  The accuracy of gypsum working casts and working dies from the new and 2 existing types of impression material were similar, for both spray and immersion disinfection. Judicious application of a die spacer can compensate for the small differences observed. VPS may require additional laboratory accommodation to compensate for a shorter working die.
authors.affiliation: Associate Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA 98195-7456, USA. mk33@u.washington.edu
authors.forename: Mats H
authors.initials: MH
authors.lastname: Kronström
authors.forename: Glen H
authors.initials: GH
authors.lastname: Johnson
authors.forename: Richard W
authors.initials: RW
authors.lastname: Hompesch
mesh_terms: D000336:Aerosols; D000704:Analysis of Variance; D019551:Dental Disinfectants / Q000008:administration & dosage / Q000737:chemistry*; D003760:Dental Impression Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design / Q000295:instrumentation*; D004203:Disinfection / Q000379:methods; D020724:Elastomers / Q000737:chemistry*; D006801:Humans; D007101:Immersion; D011145:Polyvinyls / Q000737:chemistry; D015203:Reproducibility of Results; D012117:Resins, Synthetic / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry
chemical_list: D000336:Aerosols; D019551:Dental Disinfectants; D003760:Dental Impression Materials; D020724:Elastomers; C022821:Impregum; D011145:Polyvinyls; D012117:Resins, Synthetic; D012833:Siloxanes; C480691:aquasil