Early occlusal caries detection using targeted fluorescent starch nanoparticles

We have previously shown fluorescent cationic starch nanoparticles (FCSNs) penetrate enamel surface porosity of active carious lesions, potentially aiding their detection. Here, we evaluate the in vitro diagnostic accuracy of FCSNs in detecting occlusal caries compared to histologic reference standard.

100 extracted human teeth were selected with sound (50), or either non-cavitated (25) or cavitated (25) lesions. A region of interest (ROI) on the occlusal surface was assessed for fluorescence by two independent examiners, after immersion in FCSN solution, water rinse, and illumination by dental curing lamp viewed through orange UV-filter glasses. ROIs were sectioned and evaluated by histology (Downer Criteria) as a gold standard for caries presence. Cohen's Kappa was determined for inter- and intra-examiner agreement, and sensitivity, specificity, and area under the curve of Receiver Operator Curves (ROC_AUC) were calculated. The analysis was repeated for the subset of "early" lesions, defined as being limited to enamel.

FCSN use resulted in substantial inter-user (k=0.74±0.07), and high intra-user agreement (k=0.80±0.06; 0.94±0.03, by examiner). Sensitivity, specificity and ROC_AUC for FCSNs were 88.9%; 94.6%; 0.92±0.06 for all, and 76.9%, 94.6%, and 0.86±0.10 for early lesions. In post hoc analysis, sensitivity seemed to be greater with the FCSN than the expert visual exam, particularly for early lesions.

FCSNs are a reproducible and accurate novel technology for occlusal caries detection, with high sensitivity and specificity compared to histology. Future clinical validation is necessary. FCSNs can improve early caries detection and shift treatment towards non-invasive approaches, improving oral health.