title: The effect of various interim fixed prosthodontic materials on the polymerization of elastomeric impression materials.
abstract: BACKGROUND
  After tooth preparation, interim fixed prosthodontic materials are used to fabricate interim restorations until the definitive restoration can be delivered. The polymerization of elastomeric impression materials may be inhibited when in indirect contact with interim fixed prosthodontic materials.
  
  
  OBJECTIVE
  The purpose of this study was to detect whether the polymerization of 6 commonly used types of elastomeric impression materials was affected by direct contact with 6 commonly used interim fixed prosthodontic materials and to further evaluate the efficacy of several decontamination methods to eliminate the indirect effect of the interim fixed prosthodontic materials on the setting of elastomeric impression materials.
  
  
  METHODS
  Six brands of elastomeric impression material (Virtual, Aquasil, Genie, Correct Plus, Express, Impregum) were evaluated in vitro after direct contact with various interim fixed prosthodontic materials (Trim Plus, Unifast, Integrity, Systemp C&B, Tuff-Temp, Protemp IV) by 3 general practitioners. The setting of the impression materials was visually scored as either inhibited or noninhibited. Latex was used as a positive control. The decontamination part of the study was done indirectly on the dentin of prepared natural teeth after they had been relined with the interim fixed prosthodontic material. The decontamination methods were air-water rinse, mouthwash (chlorhexidine 0.12%), 3% hydrogen peroxide, and pumice. A Kruskal-Wallis nonparametric analysis was used to evaluate the results.
  
  
  RESULTS
  Statistically significant setting inhibition was found with 5 brands of polyvinyl siloxane impression materials with all tested types of interim fixed prosthodontic material (P<.001) except Trim Plus. No tested interim fixed prosthodontic material caused inhibition with the polyether impression material, except for minimal inhibition with Protemp IV. The decontamination method performed with 3% H2O2 alone proved adequate in preventing impression material inhibition. Interexaminer reliability data were analyzed with the kappa correlation analysis. The examiners were in complete agreement (kappa +1).
  
  
  CONCLUSIONS
  Under these in vitro conditions, the direct contact of polyvinyl siloxane impression materials to some brands of interim fixed prosthodontic materials resulted in polymerization inhibition. Of the decontamination methods tested, only 3% H2O2 showed efficacy in preventing the inhibitory effect of the interim fixed prosthodontic material. For optimal results, definitive impressions should be made before the prepared tooth is exposed to an interim fixed prosthodontic material.
authors.affiliation: Assistant Professor, Department of Prosthetic Dental Sciences, King Saud University, Riyadh, Saudi Arabia. Electronic address: alsowygh@gmail.com.
authors.forename: Zeyad H
authors.initials: ZH
authors.lastname: Al-Sowygh
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000891:Anti-Infective Agents, Local / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002710:Chlorhexidine / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003760:Dental Impression Materials / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D004203:Disinfection / Q000379:methods; D020724:Elastomers / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D000891:Anti-Infective Agents, Local; D003188:Composite Resins; D003760:Dental Impression Materials; D003764:Dental Materials; D020724:Elastomers; C022821:Impregum; D008689:Methacrylates; D008768:Methylmethacrylates; D011109:Polymethacrylic Acids; D011145:Polyvinyls; D012117:Resins, Synthetic; D017640:Silicates; D012833:Siloxanes; C509714:Systemp.inlay; C480691:aquasil; C448321:integrity resin; C034183:vinyl polysiloxane; D014867:Water; C091347:vinyl ethyl methacrylate; D017438:Bisphenol A-Glycidyl Methacrylate; C069714:Protemp; C078282:G-C Unifast LC; D006861:Hydrogen Peroxide; C005144:pumice; D002710:Chlorhexidine