title: Effect of cement selection and finishing technique on marginal opening of cast gold inlays.
abstract: BACKGROUND
  The standard cement for partial-veneer cast gold restorations has been zinc phosphate. With increasing interest in using resin and resin-modified glass ionomer cements for this purpose, marginal adaptation with use of these newer cements must be assessed.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to determine if the marginal adaptation of cast gold inlays is comparable for 3 different luting agents and 3 finishing techniques.
  
  
  METHODS
  Cast gold inlays were cemented into triangular preparations on the buccal surface of 45 extracted human molars. Three operators each used a different technique for finishing margins: finishing during cementation (FD), finishing before cementation (FB), and finishing before and during cementation (FBA). The 15 teeth for each operator were divided into 3 subgroups of 5 each to accommodate 3 cements: zinc phosphate (Fleck's zinc phosphate: ZP), resin-modified glass ionomer (RelyX Luting: RXL), and self-adhesive modified resin (RelyX Unicem: RXU). For all specimens, fine sandpaper disks followed by fine cuttle disks were used for finishing the castings. The marginal gap was measured using a Nikon measuring microscope at x50 magnification. Data were analyzed with a 1-way ANOVA for each cement (alpha=.05).
  
  
  RESULTS
  There were significant differences among finishing techniques for each cement (P<.05). For ZP, the smallest mean marginal gaps were for FD (31 microm) and FBA (42 microm). For RXL, FBA produced the smallest gap (19 microm). For RXU, FB (23 microm) and FBA (22 microm) were optimal.
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, the marginal gap attained with cementation of partial-veneer cast gold restorations with ZP (31 microm) can also be obtained using RXL or RXU. The techniques of FD or FBA are best used for ZP, whereas the FBA technique is best for RXL, and either FB or FBA is optimal for RXU. The FBA technique yielded a small gap; this was common to all 3 cements.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA 98225-4035, USA. CVFDMD@aol.com
authors.forename: Charles V
authors.initials: CV
authors.lastname: Farrell
authors.forename: Charles V
authors.initials: CV
authors.lastname: Farrrell
authors.forename: Glen H
authors.initials: GH
authors.lastname: Johnson
authors.forename: Michael T
authors.initials: MT
authors.lastname: Oswald
authors.forename: Richard D
authors.initials: RD
authors.lastname: Tucker
mesh_terms: D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D003734:Dental Casting Investment / Q000737:chemistry*; D003738:Dental Cements / Q000737:chemistry*; D018772:Dental Marginal Adaptation; D003775:Dental Polishing / Q000295:instrumentation / Q000379:methods*; D003801:Dental Veneers; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry*; D006801:Humans; D007284:Inlays; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D015036:Zinc Phosphate Cement / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003734:Dental Casting Investment; D003738:Dental Cements; D005899:Glass Ionomer Cements; D006047:Gold Alloys; C483701:Rely X Unicem; D019279:Resin Cements; C084550:Vitremer; D015036:Zinc Phosphate Cement