title: [Chromatic study of all-ceramic crown--IPS Empress: difference of color by manufacturing technique and cements].
abstract: OBJECTIVE
  In recent years,aesthetic appearance and function are called for and all-ceramic crowns are spreading. By choosing an all-ceramic crown the problem of metal ceramics is avoided. There are difficulties of color tone reproducibility of cervical margin and darkness of gingival margin. We examined IPS Empress also in various all-ceramic crowns. IPS Empress has high permeability a ceramic ingot of various color tones and excellent color tone reproducibility of natural teeth. Generally a layering technique is used for an anterior tooth and the staining technique is used for a molar. However the details are unknown We examined how differences of manufacturing method and cement affect the color tone of all ceramics clinically.
  
  
  METHODS
  Two kinds of Empress crown were fabricated for a 27 year-old woman's upper left-side central incisors:the staining technique of IPS Empress and the layering technique of IPS Empress II. Various try-in pastes(transparent opaque white white and yellow) of VariolinkII of the IPS Empress System were used for cementing. Color was measured using a spectrophotometer CMS 35FS. The L*a*b* color system was used for showing a color. The right-side central incisors on the opposite side of the same name teeth were used for comparison.
  
  
  RESULTS
  We analyzed the color difference (DeltaE* ab)with a natural tooth. Consequently when it had no cement of staining technique and was tranceparent small values were obtained.
  
  
  CONCLUSIONS
  It is considered that the color tone can be adjusted by color cement. It is effective to use the staining technique for an anterior tooth crown depending on the case. The crown manufactured using the layering technique is not easily influenced by cement. The crown manufactured by the staining technique tends to be influenced by cement.
authors.affiliation: Division of Prosthodontics Department of Oral Functional Science and Rehabilitations, Asahi University School of Dentistry, Mizuho, 501-0296 Gifu. utako@dent.asahi-u.ac.jp
authors.forename: Utako
authors.initials: U
authors.lastname: Hata
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Sadamitsu
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamamura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kawauchi
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Fujii