The real performance of bitewing radiography and fiber-optic transillumination in approximal caries diagnosis

For both general practitioners and researchers in caries diagnostics, the t rue validity of available diagnostic techniques is of considerable interest . Yet, for both bitewing radiography and fiber-optic transillumination, thi s is still not accurately known, nor is it clear which of the two technique s performs best clinically. This study's purpose was to estimate the clinic al performance of the two techniques in diagnosing approximal caries lesion s in low-caries-prevalence populations. Clinical studies that compare the t wo techniques were selected from literature. We determined 2 x 2 contingenc y tables from these studies and calculated one overall contingency table. T he cut-off for decay was at dentinal caries. Assuming that erroneous outcom es from both techniques are mutually independent, we expressed diagnostic s ensitivity and specificity of the two techniques as functions of the contin gency table cell contents, with caries prevalence as the parameter. Because the caries prevalence was unknown, every sensitivity and specificity value was possible. From the conditions that sensitivity, specificity, and carie s prevalence are always between one and zero, a limited range of sensitivit y and specificity values was obtained. Three situations were examined: Bite wing radiography specificity is 1, fiber-optic transillumination specificit y is 1, and both specificities are equal. Under these conditions, the bitew ing radiography sensitivity was between 1.00 and 0.71 +/- 0.01, and the fib er-optic transillumination sensitivity was between 0.70 +/- 0.01 and 0.50 /- 0.02. Both specificities were between 1.00 and 0.99. We concluded that t he two techniques have comparable specificities, but that the fiber-optic t ransillumination sensitivity is significantly lower than that for bitewing radiography.