title: Evaluation of defects in surface detail for monophase, 2-phase, and 3-phase impression techniques: an in vitro study.
abstract: BACKGROUND
  Polyvinyl siloxane materials of various consistencies have been tested to reduce defects commonly associated with different definitive impression techniques.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to compare the number of visible defects within the surface of a new 3-phase, 2-step impression injection technique with the number found in the monophase and in the conventional 2-phase, 1-step and 2-phase, 2-step impression techniques.
  
  
  METHODS
  Two complete crown abutment preparations were impressed 10 times for each of these 4 techniques, which gave 20 abutment impressions for each group. The 3-phase, 2-step impression--injection technique included extra-light--body impression material added for the impression and injected after reinsertion. After the removal of all of these impressions, an examiner counted the number of open voids and bubble-like enclosed voids visible to the naked eye at a working distance of approximately 150 mm. Only the defects in the area of the prepared abutments were included in the assessment.
  
  
  RESULTS
  The frequency of defects ranged from 100% of the impressions in the monophase group to 5% with the new 3-phase, 2-step impression injection technique. No statistical differences were seen between the two 2-phase (1-step and 2-step) impression techniques, although there were numerically fewer impressions with defects with 2 steps (45%) than with 1 step (55%). The 3-phase, 2-step impression injection technique had the greatest accuracy, with fewer specimens with defects (5%) than with either of the 2-phase techniques, although these differences did not reach statistical significance.
  
  
  CONCLUSIONS
  The 3-phase, 2-step impression injection technique provides improved defect-free reproduction of detail, showing fewer defects than other impression techniques.
authors.affiliation: Assistant Professor, Department of Medical, Oral and Biotechnological Sciences, Dental School, 'G. D'Annunzio' University of Chieti-Pescara, Chieti-Pescara, Italy. Electronic address: gvarvara@unich.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Varvara
authors.affiliation: Aggregate Professor, Department of Medical, Oral and Biotechnological Sciences, Dental School, 'G. D'Annunzio' University of Chieti-Pescara, Chieti-Pescara, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Murmura
authors.affiliation: Research Fellow, Department of Medical, Oral and Biotechnological Sciences, Dental School, 'G. D'Annunzio' University of Chieti-Pescara, Chieti-Pescara, Italy.
authors.forename: Bruna
authors.initials: B
authors.lastname: Sinjari
authors.affiliation: Research Fellow, Department of Medical, Oral and Biotechnological Sciences, Dental School, 'G. D'Annunzio' University of Chieti-Pescara, Chieti-Pescara, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Cardelli
authors.affiliation: Professor and Head of Department of Medical, Oral and Biotechnological Sciences, Dental School, 'G. D'Annunzio' University of Chieti-Pescara, Chieti-Pescara, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Caputi
mesh_terms: D003442:Crowns; D000044:Dental Abutments; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000295:instrumentation; D020724:Elastomers / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D058105:Polymerization; D011145:Polyvinyls / Q000737:chemistry*; D016062:Porosity; D012833:Siloxanes / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D019231:Tooth Preparation, Prosthodontic / Q000379:methods; D014783:Viscosity
chemical_list: D003760:Dental Impression Materials; D020724:Elastomers; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane