title: Effect of mixing methods on mechanical properties of alginate impression materials.
abstract: BACKGROUND
  A commercial mechanical mixer is available to make the mixing of alginate more convenient and more consistent for the practitioner; however, there is very little information on the mechanical properties of alginate mixed with this device as compared with hand mixing.
  
  
  OBJECTIVE
  To compare the mechanical properties of alginate impression materials mixed with a mechanical mixer (Alginator II, Cadco) and hand mixing.
  
  
  METHODS
  Three alginate impression materials (Identic, Jeltrate, and Kromopan) were tested. Strain in compression, elastic recovery, and compressive strength were measured according to ANSI/ADA specification no. 18-1992; tear energy was measured using a pants tear test. Five specimens were prepared for each group with 12 groups for the mechanical mixer and 12 groups for hand mixing, for a total of 120 specimens. A two-way analysis of variance and Fisher's PLSD test at the 0.05 level of significance were used to analyze the data.
  
  
  RESULTS
  There were statistically significant differences in properties among the materials, but mixing technique had no statistically significant effect on strain in compression and tear energy.
  
  
  CONCLUSIONS
  The mechanical mixer improved elastic recovery and compressive strength of the alginate impression materials tested and had no effect on strain in compression and tear energy. A mechanical mixer facilitates the mixing of alginate impression materials and improves some mechanical properties.
authors.affiliation: University of Texas Dental Branch at Houston, Department of Restorative Denistry and Biomaterials, Texas 77030, USA. Gar.N.Frey@uth.tmc.edu
authors.forename: Gary
authors.initials: G
authors.lastname: Frey
authors.forename: Huan
authors.initials: H
authors.lastname: Lu
authors.forename: John
authors.initials: J
authors.lastname: Powers
mesh_terms: D000464:Alginates / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003102:Colloids / Q000737:chemistry; D019245:Compressive Strength; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000295:instrumentation; D004339:Drug Compounding; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D009930:Organic Chemicals / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D000464:Alginates; D003102:Colloids; D003760:Dental Impression Materials; D009930:Organic Chemicals; C043594:Jeltrate