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

Abstract

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*_ab and h_ab) and whiteness index for dentistry (WI_D) were calculated. Color differences (${\text{Δ}\text{E}}_{00}$, ${\text{Δ}\text{E}}_{\text{a}\text{b}}^{\text{*}}$) and whiteness differences (${\text{Δ}\text{W}\text{I}}_{\text{D}}$) 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*_ab and h_ab 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 ${\text{Δ}\text{E}}_{00}$ and ${\text{Δ}\text{E}}_{\text{a}\text{b}}^{\text{*}}$ 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_D index increased with dehydration time, while whiteness differences were clinically perceptible after 4 min. Statistically significant differences were found for WI_D 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.