title: Effect of the use of die spacer on the marginal fit of copings cast in NiCr, NiCrBe and commercially pure titanium.
abstract: The goal of this study was to evaluate the effect of using die spacers on the marginal fit of NiCr (M1) and NiCrBe (M2) alloys and commercially pure titanium (cpTi) (M3) copings cast by the lost wax technique. Using a metal matrix, 45 resin added extra hard type IV stone models were obtained for the fabrication of wax patterns under the following conditions: no die spacer (A), with one die spacer layer (B) and with two die spacer layers (C), with five repetitions for each condition (alloy x die). Each die was waxed and the wax patterns were invested as per manufacturer's instructions. Three wax patterns were embedded in each casting ring, each corresponding to one of the conditions. Each coping, seated to the metal matrix by a seating pressure standardizing device (SPSD), was taken to an optical microscope for measurement of marginal discrepancy. The obtained data (microm) were analyzed statistically by ANOVA and Tukey' test (a=5%). There was statistically significant difference (p<0.05) among the materials (M1=110.67; M2=130.33 and M3=148.33). Regarding the use of the die spacer, there was a statistically significant difference (p<0.05) among the three conditions (A=162.00; B=131.06 and C=96.67). It was concluded that there is less marginal discrepancy with two die spacer layers.
authors.affiliation: Department of Dental Materials and Prosthodontics, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Natércia Carreira
authors.initials: NC
authors.lastname: Soriani
authors.forename: Mônica Barbosa
authors.initials: MB
authors.lastname: Leal
authors.forename: Silvana Maria
authors.initials: SM
authors.lastname: Paulino
authors.forename: Valéria Oliveira
authors.initials: VO
authors.lastname: Pagnano
authors.forename: Osvaldo Luiz
authors.initials: OL
authors.lastname: Bezzon
mesh_terms: D002858:Chromium Alloys; D003442:Crowns; D003735:Dental Casting Technique; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D007283:Inlay Casting Wax; D008422:Materials Testing; D003765:Models, Dental; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014025:Titanium
chemical_list: D002858:Chromium Alloys; D007283:Inlay Casting Wax; D014025:Titanium