Impact of short-term dental dehydration on in-vivo dental color and whiteness.

Objective: To determine in-vivo chromatic and whiteness changes produced by short-term dental dehydration.

Methods: Spectral reflectance of 452 upper incisors (226 centrals and 226 laterals) of 113 participants were measured using a spectroradiometer at baseline and after short-term dehydration (minutes 2, 4, 6, 8 and 10). CIE L*a*b* color coordinates (L*, a*, b*, C* and h) and whiteness index for dentistry (WI) were calculated. Color differences (ΔE, ΔE) and whiteness differences (ΔWI) were computed and interpreted based on their respective 50:50% perceptibility (PT) and acceptability thresholds (AT). Statistical analysis was performed using the related samples Wilcoxon signed-rank test.

Results: L* showed an increasing trend with dehydration, while a*, b*, C* and h have a decreasing tendency. All chromatic coordinates showed statistically significant differences (p < 0.003) at each interval of dehydration compared with baseline, except a* for all teeth. For ΔE and ΔE values were higher than PT after 2 min of teeth dehydration and higher than AT after 6 and 8 min, respectively. The percentage of teeth exceeding corresponding PT was higher than 50% after 2 min. WI index increased with dehydration time, while whiteness differences were clinically perceptible after 4 min. Statistically significant differences were found for WI between all dehydration intervals (except 8-10 min). The percentage of teeth exceeding whiteness PT was higher than 50% after 6 min of teeth dehydration.

Conclusions: Short-term dental dehydration produces clinically unacceptable changes in tooth color and clinically perceptible increase in tooth whiteness level.

Clinical Significance: Clinical shade matching must be done within the first two minutes of any clinical procedure that requires precise chromatic determination but implies a risk of tooth dehydration.