Objective: To determine the influence of in vivo dehydration and rehydration on color and whiteness variations in maxillary anterior teeth of younger, middle-aged, and older individuals.
Methods and materials: The spectrophotometric shade of maxillary anterior teeth from younger (20 to 30 years, n=20), middle-aged (50 to 60 years, n=20) and older (65 to 80 years, n=20) participants were assessed at baseline and every 10 minutes for 30 minutes after rubber dam isolation (dehydration). The teeth were then allowed to rehydrate, and shade values were assessed every 10 minutes for 30 minutes, after 24 hours, and after 48 hours. Data were collected as International Commission on Illumination (CIE) L*a*b* color coordinates. Color differences (ΔE*ab) and whiteness differences (ΔWID) were evaluated. Statistical analysis was performed using one-way analysis of variance with the Tukey Honest Significant Difference test.
Results: The color and whiteness changes of maxillary anterior teeth in older individuals after dehydration for 30 minutes were significantly lower than that of younger and middle-aged individuals. In younger participants, after 10 minutes of dehydration, mean ΔE*ab values of maxillary anterior teeth were above the acceptability threshold (AT), while mean ΔWID values were above AT only in maxillary canines. In middle-aged participants, mean ΔE*ab values were above AT, and mean ΔWID values were above the perceptibility threshold (PT) and below AT after 10 minutes of dehydration. In older participants, mean ΔE*ab values were above PT and below AT at 20 minutes of dehydration, while mean ΔWID values were above PT at 10 minutes of dehydration, and both were above AT at 30 minutes of dehydration. The mean ΔE*ab values were above AT after 20 minutes of rehydration in younger and middle-aged participants, while they were below AT in older participants after 10 minutes of rehydration. Mean ΔWID values were below AT for older participants after 20 minutes of rehydration. All mean ΔWID values were below AT and above PT after 30 minutes of rehydration except central incisors of younger participants. After 24 hours of rehydration, mean ΔE*ab and mean ΔWID values of participants in all age groups were below AT. After 48 hours of rehydration, mean ΔE*ab and ΔWID values of participants in all age groups were below PT except mean ΔE*ab values of canines and mean ΔWID values of central incisors in younger participants. L*, a*, and b* values were significantly different between age groups at 30 minutes of dehydration and after 48 hours of rehydration (p<0.05).
Conclusion: Color and whiteness changes due to dehydration were less pronounced in older participants. Dehydration for 10 minutes in most maxillary anterior teeth of younger and middle-aged participants led to perceptible and clinically unacceptable color and whiteness changes. Maxillary anterior teeth of older participants showed color and whiteness changes that were perceptible at 10 minutes of dehydration but clinically acceptable up to 30 minutes of dehydration. After 30 minutes of dehydration, a 10- and 20-minute rehydration was needed, respectively, for color and whiteness changes to be clinically acceptable in maxillary anterior teeth of older individuals, while a 30-minute rehydration was recommended for the middle aged group and for maxillary laterals and canines of the younger group. Color and whiteness changes in most maxillary anterior teeth were imperceptible only after 48 hours of rehydration.
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