title: A clinical evaluation of the agar alginate combined impression: dimensional accuracy of dies by new master crown technique.
abstract: OBJECTIVE
  To evaluate the dimensional accuracy of several impression methods including agar alginate combined impression in vivo; the marginal accuracy of stone dies was determined using a new electroformed master crown technique.
  
  
  METHODS
  Cast cores with knife-edge and chamfer margins and electroformed master crowns were fabricated for 3 patients. Five impressions were taken of each preparation, using agar alginate combined impression and silicone impression materials. Dies were made after impression. The marginal fit of the master crown on each die was analyzed by four-way analysis of variance (ANOVA) and Tukey HSD test (p<0.05).
  
  
  RESULTS
  The marginal fit of the master crown on the dies with chamfer margin was better than those with knife-edge margin for agar alginate combined impression. The shape of the margin did not affect the accuracy when silicone impression material was used.
  
  
  CONCLUSIONS
  The results suggest that the agar alginate impression method is clinically acceptable for the chamfer margin, but shape of the margin may affect the dimensional accuracy of dies. The shape of the margin does not affect the accuracy of dies when silicone impression was used. Furthermore, the master crown made by electroforming technique could be useful for clinical evaluation of impression methods.
authors.affiliation: Fixed Prosthodontics, Department of Restorative sciences, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
authors.forename: Priyadarshanee Manorika
authors.initials: PM
authors.lastname: Ratnaweera
authors.forename: Keiichi
authors.initials: K
authors.lastname: Yoshida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Miura
authors.forename: Ariko
authors.initials: A
authors.lastname: Kohta
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Tsuchihira
mesh_terms: D000362:Agar / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry*; D000704:Analysis of Variance; D003442:Crowns; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique; D017267:Dental Prosthesis Design; D004595:Electroplating; D006801:Humans; D003765:Models, Dental; D011176:Post and Core Technique / Q000295:instrumentation; D012826:Silicone Elastomers / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000464:Alginates; D003760:Dental Impression Materials; D012826:Silicone Elastomers; D000362:Agar