The methods currently utilized in dentistry to detect caries lesions h
ave their limitations and alternatives are being investigated. A promi
sing option is tooth transillumination which is based on an increase o
f light scattering or light absorption in the affected tissue region.
In this study transillumination applied to detect approximal caries le
sions was investigated using premolar teeth containing simulated carie
s lesions. Cavities were drilled at the approximal surface and filled
with light absorbing and light scattering fluids in different dye and
particle concentrations to model successive stages of lesion progress.
For light absorbing cavities the extinction as function of the decadi
c absorption coefficient measured at the occlusal surface could be app
roximated by the Lambert-Beer law (r = 0.98 +/- 0.01). For light scatt
ering cavities the extinction as a function of the decadic reduced sca
tter coefficient wad fitted to a straight line (r = 0.98 +/- 0.03) for
mu(s)':(lambda = 633 nm) < 1.25 mm(-1). For higher reduced decadic sc
atter coefficients the curves levelled off due to multiple scattering.
In addition, the contribution of the dentinal cavity part to the radi
ance change induced by the total cavity was estimated. For light absor
bing cavities illuminated with red light the average contribution was
10.5 (SD 4.2)% and for those illuminated with green light it was 1.4 (
SD 0.9)%, indicating that the radiance change caused by a caries lesio
n is mainly determined by the enamel lesion part.