title: Assessment of perceptibility and acceptability of color difference of denture teeth.
abstract: OBJECTIVE
  To assess the color difference values that represent the perceptibility and acceptability thresholds of denture teeth.
  
  
  METHODS
  Eighteen interchangeable right upper central incisors denture teeth were selected to have color difference values from representative left upper central incisor denture tooth in a range of 0.4-11.4 ΔE* units measured with a spectrophotometer (CM 2600d, Minolta Konica, Japan). These teeth were placed in an artificial dental arch in a phantom head. Under controlled conditions, a total of 80 observers divided into 4 groups (technicians, nurses, dentists and researchers) were asked to report the perceptibility and acceptability of each of the color difference values. The findings was then analysed using logistic regression for determining the perceptible and acceptable thresholds of dental color differences.
  
  
  RESULTS
  The determined color difference values at which 50% of all observers could detect a color difference (50:50 probability) was 1.9 ΔE* units with a 95% confidence interval and ranged from 1.7 ΔE* units to 2.1 ΔE* units. The determined color difference value at which 50% of all observes preferred to replace the tooth because of unacceptable color difference (50:50 probability) was 4.2 with a 95% confidence interval that ranged from 3.9 ΔE* units to 4.7 ΔE* units.
  
  
  CONCLUSIONS
  Within the limitation of this study, the following conclusions were made: 1. The mean color perceptibility threshold was significantly lower than the mean color acceptability threshold. 2. Significant differences between different observers groups were noticed in determination of perceptibility and acceptability of color differences. The technicians groups displayed lower perceptibility and acceptability limits than the dental nurses and non-dental observers.
  
  
  CONCLUSIONS
  When shade matching artificial denture teeth to natural teeth, 50:50 perceptibility (1.9 ΔE* units) and acceptability (4.2 ΔE* units) thresholds are used to compare color difference values. The technicians group displayed lower perceptibility and acceptability limits than other observers.
authors.affiliation: School of Dentistry, University of Liverpool, United Kingdom.
authors.forename: Nabiel
authors.initials: N
authors.lastname: Alghazali
authors.forename: Girvan
authors.initials: G
authors.lastname: Burnside
authors.forename: Mohammed
authors.initials: M
authors.lastname: Moallem
authors.forename: Phil
authors.initials: P
authors.lastname: Smith
authors.forename: Antony
authors.initials: A
authors.lastname: Preston
authors.forename: Fadi D
authors.initials: FD
authors.lastname: Jarad
mesh_terms: D000328:Adult; D003118:Color Perception; D003726:Dental Assistants / Q000523:psychology; D003800:Dental Technicians / Q000523:psychology; D003815:Dentists / Q000523:psychology; D004192:Discrimination, Psychological; D004955:Esthetics, Dental; D005260:Female; D006801:Humans; D007180:Incisor; D016015:Logistic Models; D008297:Male; D008437:Maxilla; D008875:Middle Aged; D015588:Observer Variation; D017797:Prosthesis Coloring; D012108:Research Personnel / Q000523:psychology; D012684:Sensory Thresholds; D014093:Tooth, Artificial