Optical Coherence Tomography for Assessing the Severity of Dental Caries: An In Vitro Validation Study

<b>Background/Objectives</b>: Differentiating initial from moderate non-cavitated occlusal caries using intraoral radiography is challenging. This in vitro study aimed to verify the ability of Optical Coherence Tomography (OCT) to discern the extent of demineralization in non-cavitated carious lesions and discriminate between the exact caries stages. <b>Methods</b>: In total, 110 extracted molars and premolars with occlusal caries were examined by two calibrated examiners using OCT and radiography. Histological sections stained with acid red were used as the reference standard. Diagnostic accuracy was calculated by comparing OCT- and radiograph-based diagnoses with the histologic reference standard. <b>Results:</b> OCT demonstrated superior sensitivity (0.83), specificity (0.76), and overall diagnostic accuracy (0.79) for distinguishing moderate from initial lesions, outperforming intraoral radiography, which achieved a sensitivity of 0.48, specificity of 0.84, and accuracy of 0.70. McNemar's test showed a significant difference in sensitivity (<i>p</i> < 0.05), but not in specificity (<i>p</i> > 0.05), between the two diagnostic methods. <b>Conclusions:</b> These findings confirm that OCT can visualize caries progression with sufficient precision to distinguish between the initial and moderate lesion stages in an in vitro setting. Further validation in clinical trials is necessary to support OCT's application for routine caries diagnosis.