title: Influence of ceramic and cement thickness on the masking of various types of opaque posts.
abstract: BACKGROUND
  Dark-colored posts may negatively affect the esthetics of all-ceramic single unit crowns as the thin layers of luting cement may not be sufficiently opaque.
  
  
  OBJECTIVE
  This in vitro study evaluated the influence of the color of 2 commercially available nonmetallic opaque posts (carbon fiber and zirconia) and an experimental esthetic post, and the shade and thickness of luting cements on the esthetics of all-ceramic restorations.
  
  
  METHODS
  Sample disks at several thickness values were made in glass-ceramic (IPS-Empress), an experimental ceramic, a zirconia, a carbon fiber post material, a resin composite material (Z100) as reference, and a luting cement (Variolink II). A laboratory procedure, with 3 possible combinations of stapling the disks, was used. This was performed for 4 substrates, 3 cement colors at 2 thickness values, and 3 heights of ceramic disks. For each combination, the shift in color was measured with a spectrophotometer. Readings were performed for 3 conditions: (1) ability of ceramic to mask the aspect of the abutment in relation to its thickness (1.0, 1.5, or 2.0 mm); (2) effect of a change in cement color (W, Y, or B) on the final color of the ceramic; and (3) influence of cement film thickness (0.1 or 0.2 mm) on the final color of the ceramic.
  
  
  RESULTS
  When ceramic thickness was 1 mm, all other variables were visually appreciable. For ceramic thickness of 1.5 mm, color differences decreased and most differences were appreciable only with laboratory instruments. For ceramic thickness of 2.0 mm, there were no detectable, clinically relevant differences.
  
  
  CONCLUSIONS
  The final esthetic result of the all-ceramic IPS-Empress glass-ceramic restoration was not affected by the presence of different substrates with different colors when the thickness was more than 2.0 mm. When ceramic thickness decreases to 1.5 mm, it is advised to take the substrate aspects into consideration. If the ceramic thickness is less than 1.0 mm, the use of a full ceramic crown is contraindicated because color matching of the abutment is required to ensure an acceptable esthetic result. Differences in cement thickness (0.1 or 0.2 mm) may slightly affect the final result. As this parameter can be controlled by the operator only to a certain extent, it cannot be considered as a procedure to correct color. Availability of different cement shades allows only minor esthetic corrections, which might be instrumentally detectable but are clinically not relevant.
authors.affiliation: University of Siena, Siena, Italy. AVichi@mclink.it
authors.forename: A
authors.initials: A
authors.lastname: Vichi
authors.forename: M
authors.initials: M
authors.lastname: Ferrari
authors.forename: C L
authors.initials: CL
authors.lastname: Davidson
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D000077482:Carbon Fiber; D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003188:Composite Resins; D000075202:Contraindications; D003442:Crowns; D000044:Dental Abutments; D003738:Dental Cements / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D004955:Esthetics, Dental; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique; D019279:Resin Cements / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013053:Spectrophotometry; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D000077482:Carbon Fiber; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; C075815:IPS-Empress ceramic; D019279:Resin Cements; C083568:Z100 composite resin; D003776:Dental Porcelain; C103502:Variolink; D002244:Carbon; D012822:Silicon Dioxide; D015040:Zirconium; C028541:zirconium oxide