title: Correlation of natural tooth colour with aging in the Spanish population.
abstract: OBJECTIVE
  To analyse natural tooth colour in the Spanish population according to the colour coordinates lightness (L*), chroma (C*), hue (h*), red-green axis (a*) and yellow-blue axis (b*) in order to quantify the correlation and changes of tooth colour with age and sex.
  
  
  METHODS
  Natural tooth colour was measured in a sample of 1,361 Spanish participants of both sexes distributed within an age range of 16 to 89 years. The Easyshade Compact spectrophotometer was used and the CIELAB and CIELCh systems were followed.
  
  
  RESULTS
  Pearson's bivariate correlations between age and colour coordinates were highly significant for L* (r=-0.674, P≤0.001), h* (r=-0.468, P≤0.001) and C* (r=0.417, P≤0.001). The correlation between age and colour coordinates was stronger for men than for women, for all colour coordinates. The results showed that C*, b* and a* increased by 0.60, 0.56 and 0.26 units/year on average, respectively, whereas L* and h* decreased progressively with age (by 0.60 units/year, on average), and colour differences increased in a systematic way as the gap between the ages being compared grew wider.
  
  
  CONCLUSIONS
  The strongest correlation was found between age and L*, then between age and h* (both inverse relationships) and then between age and a*, C* and b* (direct relationships). In addition, a similar degree of change in the colour coordinates L*, C* and h* (of 0.60 units/year on average) was observed for natural tooth colour. Knowledge of the chromatic range of natural teeth may help to choose colour for the replacement of missing elements.
authors.affiliation: Departament of Dentistry, School of Medicine, University of Salamanca, Salamanca, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gómez Polo
authors.affiliation: Departament of Orofacial Prosthesis, Faculty of Dentistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gómez Polo
authors.affiliation: Departament of Dentistry, School of Medicine, University of Salamanca, Salamanca, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Montero
authors.affiliation: Departament of Orofacial Prosthesis, Faculty of Dentistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Martínez Vazquez De Parga
authors.affiliation: Departament of Orofacial Prosthesis, Faculty of Dentistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Celemin Viñuela
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D003116:Color; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D013030:Spain; D013053:Spectrophotometry; D055815:Young Adult
keywords: CIELCh; Natural tooth colour; Pearson′s correlation; age; gender; spectrophotometer