Near-infrared light transillumination (NIR-LT) vs clinical-visual inspection/FOTI to detect interproximal caries lesions in vivo.

Objective: To evaluate the ability of near-infrared light transillumination (NIR-LT) to detect interproximal enamel and dentinal caries lesions compared to clinical-visual inspection (VI) aided by fibre-optic transillumination (FOTI).

Method and materials: From 170 Finnish adolescents aged 15-17 years, 5294 interproximal surfaces of premolars and molars were examined first clinical-visually aided by FOTI (VI+FOTI) using the International Caries Detection and Assessment System (ICDAS) classification. Subsequently, the surfaces were examined using NIR-LT. The extent of lesions was determined using the modified NIR-LT classification based on the Söchtig criteria. For the analyses, data on upper and lower premolars and molars were combined. Distributions of lesions were presented as frequencies. Differences between VI+FOTI and NIR-LT at the tooth and tooth surface levels were analysed by Chi-square and Fisher's exact tests. Sensitivity and specificity of the NIR-LT method to detect any lesion was performed using VI+FOTI as the gold standard.

Results: By VI+FOTI, 92.4% surfaces were classified as sound and by NIR-LT, 88.2%. Enamel caries lesions were found on 7.0% of the surfaces by VI+FOTI and on 11.6% by NIR-LT. Enamel lesions identified by NIR-LT were nearly double for all examined teeth groups, except for lower molars it was 1.3-fold. In 66% of the surfaces, the differences between NIR-LT and VI+FOTI findings were statistically significant (p<0.001). The sensitivity for all teeth of NIR-LT was 48.4% and the specificity was 91.1%.

Conclusion: Radiation-free NIR-LT method shows considerable potential as a supplementary method for early detection of caries lesions among low caries prevalence adolescents.