QUANTITATIVE DIAGNOSIS OF SMALL APPROXIMAL CARIES LESIONS UTILIZING WAVELENGTH-DEPENDENT FIBEROPTIC TRANSILLUMINATION

The instruments clinically available for the diagnosis of approximal c aries lesions are inadequate to detect lesions early and quantitativel y. The aim of this study was to investigate whether wavelength-depende nt light scattering and absorption of carious tissues may be utilized for the quantitative diagnosis of these small approximal caries lesion s. Seventeen extracted premolar teeth were transilluminated at an appr oximal surface with a glass fiber, which transported the light from a halogen light bulb. Seven approximal surfaces contained a naturally de veloped small white-spot lesion, and 5 surfaces a small discolored les ion. Five teeth were sound. The occlusal surface was imaged with a CCD camera. Light in the blue and red portions of the electromagnetic spe ctrum was selected by means of Schott glass filters. From the obtained images, average effective decadic optical thickness differences were determined. These were plotted as a function of average mineral loss a ssessed by means of wavelength-independent microradiography. The corre lation coefficient between the average effective decadic optical thick ness difference and average mineral loss was (r) over cap = 0.79 (95% CI: 0.47...0.93). Different sources of variation that influence the ob served correlation were defined and quantified. From these measurement s, the correlation coefficient between average effective decadic optic al thickness difference and 'true' average mineral loss was estimated to be (r) over cap = 0.92 (95% CI: 0.77...0.97). The results indicate that early and, in principle, also quantitative diagnosis of approxima l caries lesions is feasible when wavelength-dependent light propagati on through carious tissues is utilized.