Effect of Dehydration Time on Tooth Colour Measurement in vitro

Objective: To investigate the effect of dehydration time on tooth colour measurement in vitro using colourimetry. Methods: Ten extracted human maxillary central incisors were used. L*a*b* values at the centre of the labial surface of each tooth were measured using a colourimeterr. The first measurement was performed after removal of excess water The second and third measurements were performed after the teeth had dried at room temperature for 2 h and 4 h, respectively. The colour differences (Delta E) between dehydration time points were calculated. Repeated one-way ANOVA was performed for colour values at different dehydration time points. Painvise comparison of group means (Student t test) was used to examine the differences between Delta E and I.54 Delta E (alpha = 0.05). Results: There were statistically significant changes in the L* values after 2 h and 4 h dehydration as well as between each Delta E and 1.54 Delta E. Neither 2 h nor 4h dehydration resulted in change of a* value or b* value. Conclusion: Dehydration time affected colour measurement using a colourimeter,- the teeth become lighter after dehydration for 2 h or longer.