title: Assessment of a prototype computer colour matching system to reproduce natural tooth colour on ceramic restorations.
abstract: OBJECTIVE
  The aim of this study was to assess the accuracy of a prototype computer colour matching (CCM) system for dental ceramics targeting the colour of natural maxillary central incisors employing a dental spectrophotometer and the Kubelka-Munk theory.
  
  
  METHODS
  Seventeen human volunteers with natural intact maxillary central incisors were selected to participate in this study. One central incisor from each subject was measured in the body region by a spectrophotometer and the reflectance values were used by the CCM system in order to generate a prescription for a ceramic mixture to reproduce the target tooth's colour. Ceramic discs were fabricated based on these prescriptions and layered on a zirconia ceramic core material of a specified colour. The colour match of each two-layered specimen to the target natural tooth was assessed by CIELAB colour coordinates (ΔE(*), ΔL(*), Δa(*) and Δb(*)).
  
  
  RESULTS
  The average colour difference ΔE(*) value was 2.58±84 for the ceramic specimen-natural tooth (CS-NT) pairs. ΔL(*) values ranged from 0.17 to 2.71, Δa(*) values ranged from -1.70 to 0.61, and Δb(*) values ranged from -1.48 to 3.81. There was a moderate inverse correlation (R=-0.44, p-value=0.0721) between L(*) values for natural target teeth and ΔE(*) values; no such correlation was found for a(*) and b(*) values.
  
  
  CONCLUSIONS
  The newly developed prototype CCM system has the potential to be used as an efficient tool in the reproduction of natural tooth colour.
authors.affiliation: University of Illinois Chicago, School of Dentistry, Chicago, IL 02115, United States.
authors.forename: Joshua
authors.initials: J
authors.lastname: Kristiansen
authors.forename: Maiko
authors.initials: M
authors.lastname: Sakai
authors.forename: John D
authors.initials: JD
authors.lastname: Da Silva
authors.forename: Mindy
authors.initials: M
authors.lastname: Gil
authors.forename: Shigemi
authors.initials: S
authors.lastname: Ishikawa-Nagai
mesh_terms: D003116:Color; D003124:Colorimetry / Q000379:methods; D003776:Dental Porcelain; D003793:Dental Restoration, Permanent / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007180:Incisor / Q000033:anatomy & histology; D008437:Maxilla; D012984:Software; D013053:Spectrophotometry / Q000295:instrumentation; D014070:Tooth / Q000033:anatomy & histology*
chemical_list: D003776:Dental Porcelain