Method: Six extracted intact human third molars were randomly selected, cleaned, and stored in artificial saliva at 370C. A custom positioning jig was fabricated for each tooth for reproducible color measurement. A baseline shade was recorded according to the Commission Internationale de l'Eclairage L*a*b* (CIE-L*a*b*) using a Minolta Chromameter CR-(200). Color measurement for all testing was taking at baseline, 15 min, 30 min, 2h, 12h and every 2 h thereafter until color stabilization occurred. Phase 1(dehydration-rehydration w/o bleaching): For dehydration, all teeth lightened and color stability occurred at 6 h. Rehydration of teeth to the baseline of color was achieved after 14 hours. Phase 2 (Effect of bleaching): An in-office bleach material (Zoom 25% HP) was applied to each tooth according to the Kwon technique (polyethylene wrap placed to cover the gel) for one hour. All comparisons were made to a Delta value of 2.6 (perceivable difference).
Result: Phase 1: A mean ΔL* of -13.05(±15.62) was observed for tooth dehydration with no perceivable changes in chroma Δa* and Δb*. Phase 2: In-office bleaching produced dehydration and chroma changes when measured immediately after bleaching with a mean of ΔL* =-12.45(±2.4), Δa*=0.31(±0.53), and Δb*= 3.67(±1.76). After rehydration of bleached teeth, luminosity values (ΔL*) returned to normal and only chromaticity changes (Δb*) were observed with a mean of 4.77(±1.91).
Conclusion: Within the limits of this study, in-office bleaching produced dehydration and chroma changes, represented by ΔL* and Δb*. Upon rehydration, the color changes were not as discernible. Further study will be conducted to determine the validity of these findings.
Keywords: Bleach, Color, Esthetics, Technology and Teeth
See more of: Dental Materials 11: Color and Appearance (Esthetics)