LIGHT-PROPAGATION THROUGH TEETH CONTAINING SIMULATED CARIES LESIONS

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.