Infiltration and Profiles of Mesoporous Silica Nanoparticles in Dentinal Tubules

Mesoporous silica nanoparticles (MSNs), the inorganic nanomaterials with stable physicochemical property and versatile surface functional groups, have been increasingly studied and applied in biomedical field as nanocarriers. There are a limited number of reports on their potential applications in clinical dentistry. Herein, we fabricated the fluorescence-labeled MSNs (RITC-NPs) and investigated for the first time their infiltration profiles in the dentinal tubules of extracted permanent teeth prepared by different irrigation approaches. Ethylenediaminetetraacetic acid (EDTA) enabled removal of the smear layer efficiently and exposure of the dentinal tubules on the root canal walls. Confocal scanning laser microscopy showed that the RITC-NPs could accumulate on the root canal walls, and effectively infiltrate into the dentin. In general, the fluorescence intensity in dentin from EDTA-treated group was much higher than that from the ultrasound-treated group, and stronger red fluorescence was observed at the crown and middle sections than the apical one in the EDTA group. The field-emission gun scanning electron microscopy further confirmed the infiltration effects of RITC-NPs in the dentin, through the patent dentinal tubules. The present findings on the infiltration of MSNs in the root canal system may provide a potential approach for further applying MSN-encapsulated antimicrobials in advanced endodontic therapy.