title: Assessment of preference of mixing techniques and duration of mixing and tray loading for two viscosities of vinyl polysiloxane material.
abstract: BACKGROUND
  Information regarding operators' preferences for different impression mixing techniques and duration of mixing and tray loading is limited.
  
  
  OBJECTIVE
  The purpose of this study was to assess operators' preferences, and the duration of mixing and tray loading using different mixing techniques.
  
  
  METHODS
  Thirty dentists, 30 dental assistants, and 30 inexperienced dental students evaluated mixing heavy-body vinyl polysiloxane material (VPS) using electronic mixing compared to automixing, and extra-heavy-body material using electronic mixing compared to hand mixing. Participants rated their level of preference using a scale from 0 to 10 for ease of mixing, control of loading, quality of mixing, level of cleanliness, and overall rating. The duration of mixing and tray loading was also measured. Mean values were compared within participant groups using the paired t test (alpha=.05) and between groups using 1-way analysis of variance (ANOVA) (alpha=.05). Holm's procedure was used to adjust the level of significance for the multiple comparisons.
  
  
  RESULTS
  The paired t test showed that mean values of level of preference for electronic mixing were significantly higher (P<.001 to .033) than those for automixing or hand mixing. The mean values of duration of mixing and tray loading with electronic mixing were significantly higher (P<.001 to .002) than those with automixing or hand mixing, except for students using heavy-body materials (P=.31). One-way ANOVA showed that there were no significant differences between the 3 participant groups in preference and duration of mixing and tray loading, both of heavy-body and extra-heavy-body VPS impression materials.
  
  
  CONCLUSIONS
  All participant groups preferred electronic mixing to automixing or hand mixing. Electronic mixing was significantly slower for all groups except for students using heavy-body materials. There was no significant difference between the 3 participant groups in the preference or duration of mixing and tray loading for the mixing techniques tested.
authors.affiliation: School of Dentistry, University of Washington, Seattle 98195-7456, USA.
authors.forename: Jung
authors.initials: J
authors.lastname: Nam
authors.forename: Ariel J
authors.initials: AJ
authors.lastname: Raigrodski
authors.forename: John
authors.initials: J
authors.lastname: Townsend
authors.forename: Xavier
authors.initials: X
authors.lastname: Lepe
authors.forename: Lloyd A
authors.initials: LA
authors.lastname: Mancl
mesh_terms: D000328:Adult; D000368:Aged; D003726:Dental Assistants; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000295:instrumentation*; D003815:Dentists; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D015588:Observer Variation; D011145:Polyvinyls / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D013335:Students, Dental; D014783:Viscosity
chemical_list: D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane