Development of a customized whiteness index for dentistry based on CIELAB color space

• No adequate CIELAB-based indices are available for whiteness evaluation in dentistry.
• Visual data optimization methods allowed the development of a new whiteness index-WID.
• WID is the first CIELAB-based index developed to evaluate whiteness in dentistry.
• The new index WID was validated under laboratory and typical clinical conditions.
• WID has great clinical and industrial applications for dental materials.

ObjectivesTo develop a customized CIELAB-based whiteness index for dentistry that accurately correlates to perception of tooth whiteness.MethodsFour psychophysical experiments (PE1-4) were conducted by three panels of observers (OP1-3) under diffuse/0° observation/measuring conditions and under typical clinical viewing conditions. Nine whiteness indices (WI, Z%, WIC, WIO, W31, W64, W, WLAB, W*), two yellowness indices (YID1925, YIE313) and tint of white in the CIELAB color system (T) were compared with regard to their ability to measure the perceived whiteness of human teeth. Determination coefficient (R2) and ‘% wrong decision’ (%WD) method were used as direct measures of the quality of the indices for whiteness perception in dentistry.ResultsCIELAB-based whiteness index (WID = 0.511L* −2.324a* −1.100b*) was developed through optimization from the data obtained in PE1. The proposed WID performed better than all the CIELAB and CIE1931 XYZ-based indices under laboratory and clinical conditions (only WIO was comparable to WID in PE2 and PE4).ConclusionThe validation experiments under laboratory and typical clinical conditions revealed that the proposed index WID outperformed previous indices, being the only CIELAB-based index developed for evaluation of whiteness in dentistry.