Whiteness difference thresholds in dentistry

Abstract

Objective: To determine the visual whiteness thresholds for esthetic dentistry using the whiteness index for dentistry based on CIELAB color space (WI_D).

Methods: A total of 60 observers (Dentists and Laypersons; n=30) from three research sites participated in the study. A psychophysical experiment based on visual assessments of simulated images of teeth on a calibrated display was performed. Images of simulated upper central incisors (SUCI) were consecutively displayed in pairs (60) and the whiteness of each SUCI pair was compared. WI_D was used to calculate the visual thresholds (WPT- perceptibility threshold; and WAT- acceptability threshold) with 95% confidence intervals (CI) and a Takagi-Sugeno-Kang (TSK) Fuzzy Approximation model was used as fitting procedure. Data was statistical analyzed using paired t-test (α=0.05).

Results: WPT and WAT were 0.72 (CI: 0.0-2.69; r²=0.52) and 2.62 (CI: 0.2-7+; r²=0.57) WI_D units, respectively. Significant differences (p<0.05) were found between WPT and WAT, and between dentist (WPT=0.46WI_D units; WAT=2.20 WI_D units) and layperson (WPT=0.94 WI_D units; WAT=2.95 WI_D units).

Significance: The visual whiteness difference thresholds determined with WI_D index can serve as reference values for research and manufacturing of dental materials, and for clinical practice situations such as assessing the effectiveness of bleaching treatments.

Keywords: Acceptability; CIELAB color space; Perceptibility; Whiteness index dentistry; Whiteness threshold.