Clinical shade matching best if carried out immediately after dental procedure: Study

Color differences 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.

The following results were observed-

a. L* showed an increasing trend with dehydration, while a*, b*, C*_ab and h_ab have a decreasing tendency.

b. All chromatic coordinates showed statistically significant differences (p < 0.003) at each interval of dehydration compared with baseline, except a* for all teeth.

c. For and values were higher than PT after 2 min of teeth dehydration and higher than AT after 6 and 8 min, respectively.

d. The percentage of teeth exceeding corresponding PT was higher than 50% after 2 min.

e. WI_D index increased with dehydration time, while whiteness differences were clinically perceptible after 4 min.

f. Statistically significant differences were found for WI_D between all dehydration intervals (except 8−10 min).

g. The percentage of teeth exceeding whiteness PT was higher than 50% after 6 min of teeth dehydration.

Hence, it was concluded that "Short-term dental dehydration produces clinically unacceptable changes in tooth color and clinically perceptible increase in tooth whiteness level and 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."