Diagnosis of smooth-surface enamel caries using SS-OCT

Objectives: Swept source optical coherence tomography (SS-OCT) can provide cross-sectional images of internal structure of biological tissue non-invasively. In this research, SS-OCT was used for diagnosis of enamel demineralization on smooth surfaces.

Methods: Seventy-three sites of smooth enamel surface were selected from 59 extracted teeth and examined visually (VI) by experienced and young dentists. SS-OCT observations were carried out on the same locations as where the visual 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 enamel caries was scored in each observation (0: no caries, 1: enamel demineralization without cavitation, 2: enamel caries with cavitation, 3: dentin caries); the results obtained from SS-OCT and visual inspection were compared to those of the CLSM. Sensitivity (SE), specificity (SP) and Az value of ROC curve were calculated for the detection of enamel demineralization and dentin caries, respectively.

Results: As for the detection of enamel caries, no significant difference of SE, SP, or Az was observed between VI and SS-OCT. However, when the caries was progressed into the dentin, SS-OCT showed higher SE than VI in experienced and young dentists (experienced dentist, VI: 0.46, SS-OCT: 0.92; young dentist, VI: 0.44, SS-OCT: 0.59). Az values of SS-OCT were also higher than those of VI in both experienced and young dentists (experienced, VI: 0.72, SS-OCT: 0.87; young, VI: 0.70, SS-OCT: 0.77).

Conclusions: SS-OCT could obtain the cross-sectional image of demineralized lesions noninvasively, which enabled efficient diagnosis of enamel caries progress even for young dentist. Supported by Grant-in-Aid for Scientific Research (No.23390432) from JSPS and Research Grant for Longevity Sciences (21A-8) from MHLW.