title: Comparison of the effects of friction varnish and electroforming on the retention of telescopic crowns.
abstract: BACKGROUND
  Methods to improve the retention of telescopic crowns, including the application of friction varnish and electroforming, are available. However, information about their efficiency is limited.
  
  
  OBJECTIVE
  The purpose of this study was to compare the influence of 2 different friction varnishes and an electroforming method on the retention of telescopic crowns.
  
  
  METHODS
  Thirty inner and outer crowns were fabricated from cobalt-chromium-molybdenum alloy having lengths and cervical diameters of 6 mm, 2-degree tapers, and shoulder margins of 1 mm. Fifty-μm thick layers were removed from the internal surfaces of the outer crowns with a vertical machining center to simulate wear. The retentive forces of these specimens were measured with a testing machine. FGP friction varnish (FGP Friction-Fit-System), SD friction varnish (Servo-dental), and an electroforming method (GES\Gold Electroforming System) were applied to the specimens. After the application of the 3 methods, retention values were measured, and the results analyzed with 1-way ANOVA, paired sample t test (α=.05).
  
  
  RESULTS
  The increase in the retentive forces of all specimens was statistically significant (P<.01). The mean retentive forces increased from 3.6 N to 9.8 N for group FGP, 3.6 N to 4.6 N for group SD, and 3.7 N to 6.0 N for group EF. Group FGP was significantly different from group SD and group EF (P<.05), and no significant difference was observed between group SD and group EF. Mean standard deviation values of retentive forces for group FGP before, FGP after, SD before, SD after, EF before and EF after is 0.5, 2.7, 0.6, 1.3, 0.8, 2.3, respectively.
  
  
  CONCLUSIONS
  Group FGP showed the maximum retention values. Group EF showed higher retention values than group SD.
authors.affiliation: Polatli Vocational School of Health Services, Hacettepe University, Ankara, Turkey. nozyemisci@yahoo.com
authors.forename: Nuran
authors.initials: N
authors.lastname: Özyemişci-Cebeci
authors.forename: Hüsnü
authors.initials: H
authors.lastname: Yavuzyilmaz
mesh_terms: D003442:Crowns; D003722:Dental Alloys; D017267:Dental Prosthesis Design / Q000379:methods; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D055664:Electrochemical Techniques; D017276:Friction; D010150:Paint; D014800:Vitallium
chemical_list: D003722:Dental Alloys; D014800:Vitallium