title: Elastomeric impression materials: a comparison of accuracy of multiple pours.
abstract: OBJECTIVE
  The aim of the present study is to compare the various elastomeric impression materials in terms of accuracy and dimensional stability, with respect to obtaining multiple casts from a single elastomeric impression at various times of pours.
  
  
  METHODS
  Three master dies were prepared for the impression making, two of these were made of brass containing a central hole with undercuts. The third die simulated a conventionally prepared typodont maxillary central incisor. Three elastomeric impression materials were chosen for the study. Each impression was poured at various time periods. Casts thus obtained were evaluated under a traveling microscope to evaluate various dimensional changes.
  
  
  RESULTS
  Addition silicones provided dies which were shorter in height and bigger in diameter. Polyethers provided dies which were shorter in both height and diameter. Condensation silicones showed insignificant changes from the master die at the immediate pour but deteriorated rapidly after that in subsequent pours.
  
  
  CONCLUSIONS
  None of the impression material showed a consistent behavior up to the fourth pour. They occasionally showed deviation from the pattern, but all these values were statistically insignificant. Polyethers showed lesser ability than both the addition silicones as well as the condensation silicones to recover from induced deformation.
  
  
  CONCLUSIONS
  Addition silicones as well as the condensation silicones have better ability to recover from induced deformation when compared to polyether.
authors.affiliation: Department of Prosthodontics, 102-AVijay Nagar, Krishna Nagar, Kanpur Road, Lucknow-23, Uttar Pradesh, India. drdheerajkumarb@gmail.com
authors.forename: Dheeraj
authors.initials: D
authors.lastname: Kumar
authors.forename: Anand U
authors.initials: AU
authors.lastname: Madihalli
authors.forename: K Rajeev Kumar
authors.initials: KR
authors.lastname: Reddy
authors.forename: Namrataa
authors.initials: N
authors.lastname: Rastogi
authors.forename: N T
authors.initials: NT
authors.lastname: Pradeep
mesh_terms: D000704:Analysis of Variance; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D020724:Elastomers; D017743:Equipment Reuse; D004987:Ethers; D006801:Humans; D008422:Materials Testing; D003765:Models, Dental; D011145:Polyvinyls; D012826:Silicone Elastomers; D012833:Siloxanes; D018709:Statistics, Nonparametric
chemical_list: D003760:Dental Impression Materials; D020724:Elastomers; D004987:Ethers; D011145:Polyvinyls; D012826:Silicone Elastomers; D012833:Siloxanes; C034183:vinyl polysiloxane