title: Influence of different post core materials on the color of Empress 2 full ceramic crowns.
abstract: BACKGROUND
  For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration.
  
  
  METHODS
  The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than DeltaE 1.8 between the two ceramic samples. So, DeltaE 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction.
  
  
  RESULTS
  When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (DeltaE = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (DeltaE = 2.0), but with opaque covering, the color effect became more clinically satisfactory (DeltaE = 1.8).
  
  
  CONCLUSIONS
  It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after covering the labial surface of the core with one layer of opaque resin cement.
authors.affiliation: Department of Prosthodontics, School and Hospital of Stomatology, Peking University, Beijing 100081, China. jge@163.com
authors.forename: Jing
authors.initials: J
authors.lastname: Ge
authors.forename: Xin-zhi
authors.initials: XZ
authors.lastname: Wang
authors.forename: Hai-lan
authors.initials: HL
authors.lastname: Feng
mesh_terms: D002516:Ceramics; D003116:Color; D003442:Crowns; D006801:Humans; D011176:Post and Core Technique