Whitening-dependent changes of fluorescence of extracted human teeth

To evaluate in vitro the fluorescence properties of extracted human teeth whitened with 40% hydrogen peroxide.

A total of 28 extracted human teeth were pumiced for 1 minute using a low-speed dental handpiece and a disposable rubber cup. Pre-whitening fluorescence measurements (T0), maximum excitation (Ex_max ), maximum emission (Em_max ), and maximum intensity (I_max 10⁸ ), were performed using a spectrofluorometer. After T0 measurements, the teeth were whitened using the in-office method with 40% hydrogen peroxide, three times for 20 minutes. The fluorescence parameters were measured under the same conditions 7 and 14 days after bleaching (T1 and T2, respectively).

Ex_max exhibited a broader range 7 days after whitening and decreased after 14 days. The Em_max and I_max 10⁸ displayed a narrower range after whitening. The mean Ex_max differed significantly between the time points (F = 20.09. P < .001). The corresponding analysis for the mean Em_max differed significantly between the time points (F = 16.69, P < .001). The same was true for the mean I_max 10⁸ (F = 9.69, P < .001).

Within the limitations of this study, whitening provoked statistically significant changes in fluorescence of the intact teeth in vitro.

The appearance of human teeth and dental materials and their changes upon aging and exposure to different agents (staining, whitening) is a topic of great relevance to esthetic dentistry. While some appearance parameters, such as color, translucency, and gloss, have been thoroughly studied, fluorescence and its influence on overall tooth appearance is still not well understood, yet it has influenced the development of fluorescence emitting restorative materials.