The aim of this study was to assess the difference of fluorescence signals of cement and
calculus using a 405 nm excitation wavelength.
A total number of 20 freshly extracted teeth was used. The light source used for this study
was a blue LED with a wavelength of 405nm. For each tooth the spectra of calculus and
cementum were measured separately. Fluorescence light was collimated into an optical fibre
and spectrally analyzed using an echelle spectrometer (aryelle 200, Lasertechnik Berlin,
Germany) with an additionally bandpass (fgb 67, Edmund Industrial Optics, Karlsruhe,
Germany). From these 40 measurements the median values were calculated over the whole
spectrum, leading to two different median spectra, one for calculus and one for cementum.
For further statistical analysis we defined 8 areas of interest (AOI) in wavelength regions,
showing remarkable differences in signal strength.
In 7 AOIs the intensity of the calculus spectrum differed statistically significant from the
intensity of the cementum spectrum (p < 0.05). A spectral difference could be shown between
calculus and cement between 600nm and 700nm.
Thus, we can conclude that fluorescence of calculus shows a significant difference to the
fluorescence of cement. A differentiation over the intensity is possible as well as over the
spectrum. Using a wavelength of 405nm, it is possible to distinguish between calculus and
cement. These results could be used for further devices to develop a method for feedback
controlled calculus removal.