A complete understanding of the type and location of oxidation which occurs with vital tooth bleaching may prove valuable in development of future formulations. Objectives: Studies have demonstrated that bleaching produces changes in external color (b* reductions, L* increases), internal color, and internal fluorescence. This study compared external color changes to Raman fluorescence changes in teeth bleached externally in vitro. Methods: Extracted human premolars were cleaned and analyzed for external CIELab color with a Fuji-1000CCD and stratified into treatment groups including 0; 6; 24; 48 hours bleaching (periods ABCD) in bulk 6 % H₂O₂ gel 37°C. External tooth colors were recorded post bleaching and teeth were hemi-sectioned along their vertical axis. Following this, teeth were analyzed in cross section in line scans for ultrastructural effects using non-destructive confocal laser scanning microscopy (reflection mode, He/Ne laser 632 nm). Laser light emitted from subsurface tissues was used for fluorescence and Raman spectra uptake (prototype fiber optic coupling of Raman spectrometer to CLSM, He/Ne laser 632 nm). Results: External tooth color changed exponentially with time of bleaching in vitro with maximum b* changes measuring over 4.93 and L* measuring 6.61 units. RSTI (Raman Spectrum Total Integral) reduction was compared with external b changes producing a remarkable linear correlation with r2 > 0.90. Conclusion: The changes in Raman fluorescence properties of teeth internally would appear to correlate well to external color changes produced by externally applied peroxide bleaches. These results suggest that the mechanism of vital bleaching includes phenomena more complex than simple chromagen reductions and may include changes in Raman fluorescence properties of teeth.

Back to the Mineralized Tissue Program
Back to the IADR/AADR/CADR 83rd General Session (March 9-12, 2005)

Top Level Search