title: Relative translucency of six all-ceramic systems. Part II: core and veneer materials.
abstract: STATEMENT OF PROBLEM All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material.
  
  
  OBJECTIVE
  This study compared the translucency of 6 all-ceramic materials veneered and glazed at clinically appropriate thicknesses.
  
  
  METHODS
  Core specimens (n = 5 per group) of Empress dentin, Empress 2 dentin, In-Ceram Alumina, In-Ceram Spinell, In-Ceram Zirconia, and Procera AllCeram were fabricated as described in Part I of this study and veneered with their corresponding dentin porcelain to a final thickness of 1.47 +/- 0.01 mm. These specimens were compared with veneered Vitadur Alpha opaque dentin (as a standard), a clear glass disc (positive control), and a high-noble metal-ceramic alloy (Porc. 52 SF) veneered with Vitadur Omega dentin (negative control). Specimen reflectance was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Measurements were repeated after a glazing cycle. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white backing (Yw) to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P<.05).
  
  
  RESULTS
  Significant differences in contrast ratios were found among the ceramic systems tested when they were veneered (P<.0001) and after the glazing cycle (P<.0001). Significant changes in contrast ratios (P<.0001) also were identified when the veneered specimens were glazed.
  
  
  CONCLUSIONS
  Within the limitations of this study, a range of translucency was identified in the veneered all-ceramic systems tested. Such variability may affect their ability to match natural teeth. The glazing cycle resulted in decreased opacity for all test materials except the completely opaque In-Ceram Zirconia and metal-ceramic specimens.
authors.affiliation: School of Dentistry and Dows Institute for Dental Research, University of Iowa, Iowa City, Iowa, USA. mheffernan@ureach.com
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Heffernan
authors.forename: Steven A
authors.initials: SA
authors.lastname: Aquilino
authors.forename: Ana M
authors.initials: AM
authors.lastname: Diaz-Arnold
authors.forename: Debra R
authors.initials: DR
authors.lastname: Haselton
authors.forename: Clark M
authors.initials: CM
authors.lastname: Stanford
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Vargas
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D003801:Dental Veneers; D005898:Glass / Q000737:chemistry; D006801:Humans; D008027:Light; D008277:Magnesium Oxide / Q000737:chemistry; D016876:Metal Ceramic Alloys / Q000737:chemistry; D008903:Minerals / Q000737:chemistry; D055095:Optics and Photonics; D011176:Post and Core Technique; D013053:Spectrophotometry; D013223:Statistics as Topic; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
chemical_list: C105314:AllCeram; D000538:Aluminum Silicates; D003764:Dental Materials; C075815:IPS-Empress ceramic; D016876:Metal Ceramic Alloys; D008903:Minerals; C111130:spinell; C111324:vitadur alpha omega; D003776:Dental Porcelain; C070870:In-Ceram; D008277:Magnesium Oxide; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide