Objective This study aimed to evaluate the potency of optical coherence tomography (OCT) to detect earlyocclusal caries compared with clinical visual examination. Methods Approximately 97 sites of occlusal fissures on 77 extractedaccessional human teeth were scored by three examiners using conventional visual examination and OCT. Results of histologicalexamination on these sites obtained by polarimicroscope served as a gold standard to analyze the sensitivity (SE), specificity(SP), positive predictive value (PPV), and negative predictive value (NPV). Results of the area under receiver operatingcharacteristic (ROC) curve (AUC) by visual examination and OCT were also analyzed. The Spearman’s rank correlationcoefficient with histology and the inter-examiner reliability were compared. Results For sites of enamel demineralizationlimited to the outer 1/2 of the enamel layer, the detection rate of OCT (14/25) was obviously higher than that of the clinicaland visual examination (3/25). SE, SP, PPV and NPV of OCT during diagnosis of the early occlusal caries (0.83, 0.64, 0.87and 0.57) were higher than that of the visual examination (0.79, 0.60, 0.85 and 0.50). AUC (95%CI) of OCT and the visualexamination were 0.737 (0.569-0.822) and 0.696 (0.614-0.859), respectively. No statistically significant difference was observedbetween the results. Results of OCT correlated well with histology (r=0.559,P
