title: Clinical efficacy of polyvinyl siloxane impression materials using the one-step two-viscosity impression technique.
abstract: BACKGROUND
  Impression making is a challenging clinical procedure for both patients and dentists.
  
  
  OBJECTIVE
  The purpose of this clinical study was to compare a recently introduced fast-setting polyvinyl siloxane (PVS) impression material with heavy body/light body (HB/LB) combination (Imprint 4; 3M ESPE) (experimental group) with a conventional PVS impression material with HB/LB combination (Imprint 3; 3M ESPE) (control group), using the 1-step 2-viscosity impression technique.
  
  
  METHODS
  Two definitive impressions (1 of each material combination) were made of 20 crown preparations from 20 participants. The quality of impressions was rated by 3 evaluators (clinical evaluator, clinical operator, and dental technician) and by the patients for the level of comfort and taste of the impression materials. The order in which the 2 impressions were made with each material combination was randomized for each crown preparation. A paired t test for paired means and McNemar test for paired proportions were used for statistical comparisons (α=.05).
  
  
  RESULTS
  Participants rated the comfort of the impression making with the experimental group significantly higher than that with the control group (P=.001). No significant differences were found in participants' rating for the taste of the impression materials (P=.46). The viscosity for tray material was rated as significantly better for the control group by the clinical operator (P=.004). The readability of the impression and visibility around the finish line were rated as significantly better for the experimental group than for the control group (P<.001). Except for the ease of removal of the stone (RS), the ratings for the 2 groups by the dental technician were similar. The ease of RS was rated as significantly better for the experimental group (P<.001). Eleven dies from the control and 9 from the experimental group were selected for fabrication of the definitive crowns (P=.65).
  
  
  CONCLUSIONS
  Within the limitations of this clinical study, no significant differences were found in the overall clinical performance of the experimental and the control groups. Impressions made with both materials were clinically acceptable. Participants rated the comfort provided by the experimental group significantly better than that of the control group.
authors.affiliation: Assistant Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash. Electronic address: samido@uw.edu.
authors.forename: Sami
authors.initials: S
authors.lastname: Dogan
authors.affiliation: Clinical Associate Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
authors.forename: E Ricardo
authors.initials: ER
authors.lastname: Schwedhelm
authors.affiliation: Master Dental Technician, Aesthetic Dental Creations, Mill Creek, Wash.
authors.forename: Harald
authors.initials: H
authors.lastname: Heindl
authors.affiliation: Research Associate Professor, Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, Wash.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Mancl
authors.affiliation: Professor, Department of Restorative Dentistry, School of Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
authors.forename: Ariel J
authors.initials: AJ
authors.lastname: Raigrodski
mesh_terms: D000328:Adult; D000368:Aged; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry; D001252:Astringents / Q000737:chemistry; D001291:Attitude of Health Personnel; D001294:Attitude to Health; D002133:Calcium Sulfate / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D003442:Crowns; D003734:Dental Casting Investment / Q000737:chemistry; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000592:standards*; D003800:Dental Technicians / Q000523:psychology; D003815:Dentists / Q000523:psychology; D060745:Gingival Retraction Techniques / Q000295:instrumentation; D006801:Humans; D008875:Middle Aged; D003765:Models, Dental; D011145:Polyvinyls / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D013499:Surface Properties; D013649:Taste; D014783:Viscosity
chemical_list: D017607:Aluminum Compounds; D001252:Astringents; D002712:Chlorides; D003734:Dental Casting Investment; D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D000077410:Aluminum Chloride; D002133:Calcium Sulfate