title: A clinical study relating CIELCH coordinates to the color dimensions of the 3D-Master System in a Spanish population.
abstract: BACKGROUND
  The 3D-Master System comprises 26 physical shade tabs and intermediate shades. Determining the relationship among all the groups of lightness, chroma, and hue of the 3D-Master System (Vita Zahnfabrik) and the L*, C*, and h* coordinates is important, because according to the manufacturer, 2 Toothguide 3D-Master shades need to be mixed in a 50:50 ratio to create an intermediate shade.
  
  
  OBJECTIVE
  The purpose of the study was to relate the lightness, chroma, and hue groups of the 3D-Master System with the polar coordinates of the CIELAB chromatic space, L*, C*, and h*, and to quantify the shades tabs and intermediate shades of the 3D-Master System according to color coordinates.
  
  
  METHODS
  The middle third of the facial surface of a natural maxillary central incisor was measured with an Easyshade Compact spectrophotometer (Vita Zahnfabrik) in 1361 Spanish participants aged between 16 and 89 years. Natural tooth color was recorded in the 3D-Master nomenclature and in the CIE L*, C*, and h* coordinates system. The program used for the present descriptive statistical analysis of the results was SAS 9.1.3.
  
  
  RESULTS
  In the L* variable, the minimum was found at 47.0 and the maximum at 91.3. In the C* variable, the minimum was found at 5.9 and the maximum at 49.8, while for h*, the minimum was 67.5 degrees and the maximum 112.0 degrees.
  
  
  CONCLUSIONS
  Despite the limitations of this study, the 3D-Master System was found to be arranged according to L*, C*, and h* coordinates in groups of lightness, chroma, and hue. The corresponding groups of lightness, chroma, and hue can be estimated on the basis of L*, C*, and h* coordinates.
authors.affiliation: Associate Professor, Department of Dentistry, School of Medicine, University of Salamanca, Salamanca, Spain. Electronic address: crisgodent@usal.es.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gómez-Polo
authors.affiliation: Associate Professor, Department of Orofacial Prosthesis, University Complutense of Madrid, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gómez-Polo
authors.affiliation: Tenured Lecturer of Prosthodontics, Department of Orofacial Prosthesis, University Complutense of Madrid, Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Celemín Viñuela
authors.affiliation: Tenured Lecturer of Prosthodontics, Department of Orofacial Prosthesis, University Complutense of Madrid, Madrid, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Martínez Vázquez de Parga
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003116:Color; D003118:Color Perception / Q000502:physiology; D003430:Cross-Sectional Studies; D017267:Dental Prosthesis Design / Q000295:instrumentation* / Q000592:standards; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D017797:Prosthesis Coloring / Q000295:instrumentation* / Q000592:standards; D013030:Spain; D013053:Spectrophotometry / Q000295:instrumentation; D009626:Terminology as Topic; D019228:Tooth Crown / Q000033:anatomy & histology; D055815:Young Adult