Diagnostic accuracy of a bioluminescence system for the assessment of caries activity on occlusal surfaces

Objective: Assessment of caries lesion activity is usually performed using visual-tactile criteria. A new approach is to use a system consisting of a photoprotein, which is specific for free calcium ions, along with an integrated camera that visualizes the elevated calcium ions on the lesion as a light signal (bioluminescence). This study aimed to evaluate the reproducibility and diagnostic accuracy of a newly developed bioluminescence system to assess caries lesion activity on occlusal surfaces in vitro. Materials and Methods: Ninety-four extracted permanent teeth with sound surfaces and both active and inactive caries lesions were included. The extent and activity of the investigation sites were classified visually according to the International Caries Detection and Assessment System. Digital images of the teeth were produced by the bioluminescence system and the images were analyzed for the presence of caries activity (the bioluminescent areas at the investigation sites). The images were reanalyzed after 4 weeks. Teeth were hemisected and methyl red dye was applied on the sections to validate lesion activity histologically. Results: Agreement between the bioluminescence readings was shown by K values of 0.802-0.917. A significant positive correlation (p < 0.001) was found across all methods (r(s) 0.618-0.811). Sensitivity and specificity for activity assessment using histology as the gold standard (cut-off: active/inactive) were, respectively, 83.6 and 85.0% for the visual assessment, and 92.5 and 90.0% for the bioluminescence method. Comparison of areas under the receiver-operating characteristic curves showed no significant difference between the visual and bioluminescence systems (p = 0.094). Conclusion: The bioluminescence system demonstrated high in vitro reproducibility and good diagnostic accuracy for activity assessment of caries lesions on occlusal surfaces which were not significantly different from the values obtained in the visual assessment