title: Clinical Study of the 3D-Master Color System among the Spanish Population.
abstract: OBJECTIVE
  To study whether the shades of the 3D-Master System were grouped and represented in the chromatic space according to the three-color coordinates of value, chroma, and hue.
  
  
  METHODS
  Maxillary central incisor color was measured on tooth surfaces through the Easyshade Compact spectrophotometer using 1361 participants aged between 16 and 89. The natural (not bleached teeth) color of the middle thirds was registered in the 3D-Master System nomenclature and in the CIELCh system. Principal component analysis and cluster analysis were applied.
  
  
  RESULTS
  75 colors of the 3D-Master System were found. The statistical analysis revealed the existence of 5 cluster groups. The centroid, the average of the 75 samples, in relation to lightness (L*) was 74.64, 22.87 for chroma (C*), and 88.85 for hue (h*). All of the clusters, except cluster 3, showed significant statistical differences with the centroid for the three-color coordinates (p <0.001).
  
  
  CONCLUSIONS
  The results of this study indicated that 75 shades in the 3D-Master System were grouped into 5 clusters following coordinates L*, C*, and h* resulting from the dental spectrophotometer Vita Easyshade compact. The shades that composed each cluster did not belong to the same lightness color dimension groups. There was no special uniform chromatic distribution among the colors of the 3D-Master System.
authors.affiliation: Department of Dentistry, School of Medicine, University of Salamanca, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gómez-Polo
authors.affiliation: Department of Orofacial Prosthesis, Faculty of Dentistry, Complutense University, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gómez-Polo
authors.affiliation: Department of Orofacial Prosthesis, Faculty of Dentistry, Complutense University, Madrid, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Martínez Vázquez de Parga
authors.affiliation: Department of Orofacial Prosthesis, Faculty of Dentistry, Complutense University, Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Celemín-Viñuela
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017267:Dental Prosthesis Design; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007180:Incisor / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D017797:Prosthesis Coloring / Q000379:methods*; D013030:Spain; D013053:Spectrophotometry; D055815:Young Adult
keywords: 3D Master System; CIELCh system; Spectrophotometry; Toothguide 3D-Master; cluster analysis; dental shade guide; natural tooth color