title: Evaluation of outgassing, tear strength, and detail reproduction in alginate substitute materials.
abstract: OBJECTIVE
  To compare three alginate substitute materials to an alginate impression material for cast surface porosity (outgassing), tear strength, and detail reproduction.
  
  
  METHODS
  Detail reproduction tests were performed following American National Standards Institute/American Dental Association (ANSI/ADA) Specification No. 19. To measure tear strength, 12 samples of each material were made using a split mold, placed in a water bath until testing, and loaded in tension until failure at a rate of 500 mm/min using a universal testing machine. For cast surface porosity testing, five impressions of a Teflon mold with each material were placed in a water bath (37.8°C) for the in-mouth setting time and poured with vacuum-mixed Silky Rock die stone at 5, 10, 30, and 60 minutes from the start of mixing. The gypsum samples were analyzed with a digital microscope for surface porosity indicative of hydrogen gas release by comparing the surface obtained at each interval with four casts representing no, little, some, and significant porosity. Data analysis was performed using parametric and Kruskal-Wallis analysis of variance (ANOVA), Tukey/Kramer post-hoc tests (α=0.05), and individual Mann-Whitney U tests (α=0.0167).
  
  
  RESULTS
  All alginate substitute materials passed the detail reproduction test. Tear strength of the alginate substitute materials was significantly better than alginate and formed three statistically different groups: AlgiNot had the lowest tear strength, Algin-X Ultra had the highest tear strength, and Position Penta Quick had intermediate tear strength. Significant variation in outgassing existed between materials and pouring times (p<0.05). All alginate substitute materials exhibited the least outgassing and cast porosity 60 minutes after mixing.
  
  
  CONCLUSIONS
  Detail reproduction and tear strength of alginate substitute materials were superior to traditional alginate. The outgassing effect was minimal for most materials tested. Alginate substitute materials are superior replacements for irreversible hydrocolloid.
authors.affiliation: University of Alabama at Birmingham, Birmingham, AL 35294, USA. rbaxter@uab.edu
authors.forename: R T
authors.initials: RT
authors.lastname: Baxter
authors.forename: N C
authors.initials: NC
authors.lastname: Lawson
authors.forename: D
authors.initials: D
authors.lastname: Cakir
authors.forename: P
authors.initials: P
authors.lastname: Beck
authors.forename: L C
authors.initials: LC
authors.lastname: Ramp
authors.forename: J O
authors.initials: JO
authors.lastname: Burgess
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry; D003734:Dental Casting Investment / Q000737:chemistry; D003760:Dental Impression Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D011145:Polyvinyls / Q000737:chemistry*; D016062:Porosity; D012833:Siloxanes / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000464:Alginates; D003734:Dental Casting Investment; D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D014867:Water; D002133:Calcium Sulfate