Validation of swept-source optical coherence tomography (SS-OCT) for the diagnosis of occlusal caries

In this laboratory study, we examined the use of a swept-source optical coherence tomography (SS-OCT) as a diagnostic tool for occlusal caries.

One-hundred and eleven investigation sites of occlusal fissures were selected from 62 extracted teeth and examined visually using conventional dental equipment without any magnification. SS-OCT observations were carried out on the same locations as where the conventional examination had been performed. The teeth were then sectioned using a diamond saw and directly viewed under a confocal laser scanning microscope (CLSM). Presence and extent of caries was scored in each observation and the obtained results from SS-OCT and conventional visual inspection were compared with the CLSM. The reproducibility and indices of sensitivity and specificity of SS-OCT were calculated and compared with those of the visual inspection. The results were statistically analyzed using receiver operating characteristic (ROC) curve and Spearman rank correlation test.

SS-OCT could clearly detect the presence of enamel demineralization lesion in a tomography image synthesized based on the backscatter signal (sensitivity=0.98). Although the sensitivity for dentine caries of SS-OCT was over that of the visual inspection, the detection level was decreased to 0.60. When the methods were compared to the CLSM, the diagnostic accuracy of SS-OCT was better than that of the conventional visual inspection (Az values of visual inspection and SS-OCT, 0.74 versus 0.86 for enamel demineralization, 0.68 versus 0.80 for dentine caries; Spearman's correlation coefficients to CLSM; visual inspection: 0.665, SS-OCT: 0.824).

The carious demineralization, especially in enamel, can be clearly discriminated as a highlighted area due to scattering of light matches the location of demineralized area at the base of the fissure and the results correlated well with the CLSM.