Early occlusal caries detection using targeted fluorescent starch nanoparticles.

OBJECTIVES: 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. METHODS: 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 (ROCAUC) were calculated. The analysis was repeated for the subset of "early" lesions, defined as being limited to enamel. RESULTS: 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 ROCAUC 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. CONCLUSIONS/CLINICAL SIGNIFICANCE: 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.

Nanoparticle-Based Targeting and Detection of Microcavities.

Although dental caries is the most prevalent oral disease worldwide, currently, many dentists continue to use the traditional mirror and probe (dental explorer) method of caries diagnosis. This method of caries detection has the drawback that it is often difficult to distinguish between active and inactive carious lesions. In this work, novel bio-based nanoparticles are developed to specifically detect active caries in vitro. The nanoparticles are made from a cationic fluorescein-labeled food-grade starch in order to fluoresce when illuminated by a standard dental curing light, and to degrade in the oral cavity into nontoxic compounds after detecting the active carious lesion. When exposed to extracted human teeth, cationic fluorescent (+5.8 ± 1.2 mV) nanoparticles (size 101 ± 56 nm) selectively illuminate active caries, but not the healthy tooth surface. Two-photon microscopy confirms the selective binding and accumulation of cationic fluorescent nanoparticles into microscopic carious pores in enamel. These novel nanoparticles provide a unique method to assist in the early diagnosis of active carious lesions with the potential to directly impact dental treatment.