title: Effect of alloy recasting on the color of opaque porcelain applied on different dental alloy systems.
abstract: BACKGROUND
  The effect of different proportions of recast dental alloys on the color of overlying opaque porcelain (OP) is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to compare the color of OP applied on 2 different proportions (50% and 100%) of recast alloys with the color of commercially available shade tabs of OP.
  
  
  METHODS
  Six different metal alloy systems (2 base: Metalloy CC, Cr-Co [B-MCC]; Heraenium NA, Ni-Cr [B-HNA]; 3 noble: Cerapall 2, Pd-Au [N-CP2]; Triumph, Pd-Ag [N-T]; V-Deltaloy, Au-Pd [N-VD]; and 1 high-noble: V-Gnathos Plus, Au-Pt [HN-GP]) were selected for the fabrication of disk-shaped specimens (10 mm in diameter, 1 mm in thickness). Each alloy was divided into 2 subgroups: 50% new alloy with 50% recast alloy (n=3) and 100% recast alloy (n=3). OP (B1) was applied (0.1 mm) to all specimens. The color coordinates (L*, a*, b*) of each specimen and the corresponding commercially available OP shade tab (control) were measured with a spectroradiometer, and color differences between specimens and control group were calculated. Data were statistically analyzed (2-way ANOVA, Ryan-Einot-Gabriel-Welsch multiple range test, α=.05).
  
  
  RESULTS
  For each alloy, ΔL*(L(control)(-)L(recastalloy)) values for the 2 subgroups were not statistically different from each other. The Δa* and Δb* of different proportions of N-CP2, B-HNA, N-VD, and HN-GP were not statistically different within the alloys. However, the a* values of 100% recast N-T and B-MCC were significantly closer to the a* values of the control group, and the b* values of 50% recast B-MCC were significantly closer to the b* values of the control group (P<.05). Delta E(control-recast) alloy values for different proportions of alloys were not statistically different. However, color differences did not meet the criterion of clinical acceptability (ΔE=3.46).
  
  
  CONCLUSIONS
  According to the results of this study, the different proportions (50% and 100%) of recast alloys used have similar effects on the color of OP. Differences between the final color of OP on the recast alloys used and the color of OP shade guide tabs did not meet the criterion of clinical acceptability considered in this study.
authors.affiliation: Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, Ohio 43210, USA. yilmaz.16@osu.edu
authors.forename: Burak
authors.initials: B
authors.lastname: Yilmaz
authors.forename: Tuncer B
authors.initials: TB
authors.lastname: Ozcelik
authors.forename: William M
authors.initials: WM
authors.lastname: Johnston
authors.forename: Sevcan
authors.initials: S
authors.lastname: Kurtulmus-Yilmaz
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Company
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003116:Color; D003722:Dental Alloys / Q000737:chemistry*; D003735:Dental Casting Technique / Q000295:instrumentation; D045662:Dental Etching / Q000379:methods; D003776:Dental Porcelain / Q000737:chemistry*; D006047:Gold Alloys / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D010165:Palladium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D017797:Prosthesis Coloring; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D014618:Vacuum
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D006047:Gold Alloys; D003776:Dental Porcelain; D012834:Silver; D010984:Platinum; D010165:Palladium; D000537:Aluminum Oxide